Why I'm getting the updated Covid shot

I'm scheduled for next weekend actually.

I’m getting the new updated Covid vaccine as it rolls out this week.

The CDC has advised everyone aged six months and older to receive the 2024-2025 Covid-19 vaccine - now if they haven’t been infected in the past 3-4 months. Last week the FDA approved the mRNA offerings from Pfizer and Moderna, while they are still reviewing the data from Novavax as of this writing.

I hope you will find this post helpful when you need to make your own decision, or to engage with someone who is saying the CDC is totally corrupt, incompetent, or just a shill for pharma. CDC and FDA are certainly not perfect, but consensus and policy derived through expertise is better than performative cherry picking from self-proclaimed individual experts. Read on.

Assuming I don’t contract Covid this week, I am currently scheduled to roll up my sleeve next weekend at a local Philly CVS to start priming my immune system against these newer variants. Although the mRNA vaccine we can get is targeting the KP.2 variant, and the currently cresting wave has KP.3 and KP.3.1.1 making up 54% of infections (with KP.2.3 coming in 3rd at 14%, and KP.2 down to just 3%), the updated shots are still much closer to what’s going around than my last shot in the fall of 2023. As of this writing I have not had Covid this summer.

Granted, this is an easier decision for me as I do not react strongly to these vaccines. Some people are knocked out for days, and a quite small number have absolutely experienced serious adverse reactions.

But for most people, the benefits outweigh the risks, hence the consensus guidelines and authorization.

You can see that KP.2 spawned most of the current variants, and is close enough in the evolutionary tree for me (top right):

Many people, nay the majority of people in the U.S., will be choosing not to get the updated vaccines. The older generation will have the highest uptake, while the younger generations will have predictably low rates. Is this wise? Is a precautionary approach to lingering unknowns about repeat vaccinations better than taking our chances with repeat Covid infections unprimed by recent vaccination?

We don’t have the absolute certainty to answer these questions, but a lot of doctors especially here on Substack will minimize the risk of contracting the virus, just as they will maximize the hypothetical concerns about safety and efficacy of the updated vaccines. It’s a shame, really.

So instead of telling you what to do, I’m going to tell you what I’m going to do. I’m getting the updated vaccine. I’m going to present the studies and evidence about boosters that I’ve previously highlighted in my 2024 Covidlandia series and that inform my decision. I’ll then refer you to a list of 50+ quality studies showing net benefit from boosters and staying up to date with Covid vaccines so far. This virus moves fast, and by the time you might lasso it with a great randomized controlled trial (RCT) it has already leapt the fence as a distant variant from the one you were studying. So we do our best with mostly observational studies, as the proof of benefit just keeps piling up for staying up to date with Covid vaccinations.

For the next 50 years we will still be learning about the cumulative effects of repeat vaccinations just as we learn about the cumulative effects of repeat Covid infections. I get my flu shot every year, and recently summarized the case for that. And so if cool scientific heads tell us the preponderance of evidence supports the benefits of the updated Covid shots outweighing the possible risks… who am I to argue? Who are we to argue?

Ok, so here’s the stuff I’ve highlighted about updated vaccines and booster studies in my Covidlandia 2024 series. It’s intentionally and by necessity long. It is dutifully well-referenced. Not fun summer vacation reading, though. After that I’m going to copy and paste 50+ more studies in support of Covid boosters and updated shots, as collected by Dr. Jonathan Howard who writes at ScienceBasedMedicine.org.

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*From my January letter:

A pre-print from Netherlands data showed a 70% vaccine effectiveness against hospitalization and ICU admission for those who got the XBB booster THIS FALL (2023 data).

This was officially published, too

I’m going to keep getting every updated vaccine offered or recommended. The data has never shown it’s better to skip a dose. I’m used to the idea of a yearly flu shot and have been for decades. Covid shots should be the same kind of paradigm, with perhaps every 6 months for the elderly and those at highest risk… until we come up with a better vaccine, nasal vaccine boost, etc.

Vaccines, and an increasing number of doses, positively correlate with prevention of post-Covid conditions (PCC, i.e. long Covid).

I love this one. Effectiveness at preventing PCC:

21% [1 dose]

59% [2 doses]

73% [≥3 doses]

The scale of the covid-19 pandemic showed the importance of post-viral conditions, an area of medicine that had been relatively neglected. Post-viral conditions can be disabling, fluctuant, and chronic.

Updated Covid vaccines and boosters keep helping kids, too.

In a U.S. surveillance study from July 2022–September 2023, vaccinated children aged 6 months–4 years had fewer emergency room visits and hospitalizations with COVID-19 than unvaccinated children.

Vaccine effectiveness for preventing ER visits or hospitalization in those receiving >2 vaccine doses was 40.0% when compared to unvaccinated children.

Another study showed that Covid vaccination in kids was extremely (>90%) effective at preventing severe disease and hospitalization in kids during the previous Delta and Omicron waves.

Over 2,000 have died in the United States from Covid, with many also developing lasting damage from infection.

COVID-19 vaccine is tied to a 40-50% lower risk of long COVID in kids

Long Covid is estimated to affect 0.5 - 2% of children. Doesn’t sound that bad, but multiply that by 73 million children under age 18 in the U.S.

Do you know what the long term effects of repeat Covid infections will be on kids in 20 years? Me neither. I worry about that, much more than I would consider worrying about approved vaccines.

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*From my February letter:

Updated vaccines keep working

The updated XBB Covid vaccine, which only 22% of American adults received this fall/winter, provided approximately 54% protection against symptomatic SARS-CoV-2 infection when compared with not getting the updated vaccine.

This updated vaccine was specifically found to provide good protection against the JN.1 variant which has dominated for months, and has also worked well against other circulating lineages.

What’s more, the new updated vaccine continued to provide 49% protection out to 119 days studied after the shot (about 4 months and counting).

So I’m sticking with this CDC conclusion: All persons aged ≥6 months should receive the updated 2023–2024 COVID-19 vaccine. CDC will continue monitoring COVID-19 vaccine effectiveness, including against severe disease and for expected waning.

Many of my patients who had not received the updated vaccine did so during their regularly scheduled appointments with me this fall and winter. I am grateful for that kind of trust. This kind of study helps our conversation big time. Who doesn’t want a 50% lower risk of getting Covid for a while?

A Canadian study found a similar conclusion - updated vaccines increase protection

The updated, currently available XBB.1.5 vaccine afforded a level of protection comparable to the seasonal influenza vaccine, reducing the risk of outpatient medical visits for COVID-19 by about 50% overall.

Among people reporting a prior history of confirmed Covid illness, the XBB booster provided even higher protection, reducing the COVID-19 risk by around 70%. Who doesn’t want a 70% lower risk of getting Covid for a while?

Between October and November of this year the VAST majority - 95% of hospitalized adults - were not up-to-date on their annual Covid-19 vaccines.

The more vaccine doses, the more protection against long Covid, cardiovascular disease, and mortality

A new study published in Nature Communications of almost 1.2 million people in Hong Kong demonstrates the protective effect of Covid-19 vaccination against long Covid, and suggests that the more doses people have had the less likely they will experience long-term symptoms related to the virus.

• Unvaccinated participants with Covid had the greatest risk of all observed clinical sequelae, including major cardiovascular diseases (>4 times the risk).

• Participants with 1 dose prior to infection had 3X the risk of subsequent cardiovascular disease

• Those receiving 2 doses had a 2.5X the risk of CV disease

• Those receiving 3 or more doses had “only” 2X the risk of CV disease

The risk of all-cause mortality was most significant between the unvaccinated and vaccinated, with almost a fivefold reduction in risk of all-cause mortality between unvaccinated patients and patients with complete vaccination during the acute phase of infection. The risk of all-cause mortality dropped even further among patients with a booster dose of vaccine.

After the first 30 days following infection, risk of death continued to be significantly lower for those fully vaccinated and boosted against COVID-19, with participants who received three or more doses of vaccines not incurring any significant risk of clinical sequelae from 91 days onward from their initial infection.

Vaccines continue to work well for kids

For any parents who are still considering whether or not to vaccinate their kids, these numbers are hard to argue with:

• Among adolescent 12 to 15 year-olds during the Delta period, vaccine effectiveness (VE) was 98.4% against SARS-CoV-2 infections —> 99.0% (mild disease), 98.7% (moderate-to-severe disease) and 99.0% (ICU admissions).

• Corresponding VEs during Omicron in adolescents were 85.5% —> 87.0%, 84.8%, and 91.5%.

• Among children 5 to 11 year-olds during Omicron, VE was 74.3% —>

  73.5%, 75.5%, and 84.9%.

What about myocarditis? In this study, published in Annals of Internal Medicine, risk for myocarditis was similar in the vaccinated versus unvaccinated groups during Delta, and lower in the vaccinated groups during Omicron.

Kids that received the bivalent booster last year did great

They had a 54% reduction in Covid illnesses.

Good for them, their families, their schools, and their communities. Published in JAMA.

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*From my March letter:

A guy received up to 217 Covid vaccinations

This was stunning, and chances are you’ve already heard about it. Reported in The Lancet Infectious Diseases, this erratic 62 year-old individual did afford researchers a rare chance to see what happens when the immune system is bombarded repeatedly with Covid vaccines:

From November 2019 to October 2023, 62 routine clinical chemistry parameters revealed no abnormalities attributable to hypervaccination, and SARS-CoV-2 antigen tests, polymerase chain reaction (PCR) tests, and nucleocapsid serologic tests showed no evidence of past COVID-19 infection. The man reported no vaccine-related adverse effects.

The man had more T-effector cells against SARS-CoV-2 than did a control group of three-dose recipients, and these cells were just as effective in fighting the virus after long-term overexposure. He also had a similar number of memory T cells, the progenitors of effector cells. Indeed, his levels of SARS-CoV-2 antibodies increased significantly even after the 217th dose, and the immune system's effectiveness against other pathogens was unchanged.

NO ONE should do this. But the case report does provide an almost satirical undermining of the fears the anti-vaccine forces continually stoke. Vaccines have rare and real risks, but much greater and common benefits across populations. Our bodies are constantly exposed to countless antigens from bacteria, viruses, and fungi, and our immune systems can handle the additional stimulation from a single vaccination. And perhaps 217, but never to be repeated.

In a large study, vaccination was associated with 30% to 50% lower risk for long COVID in all age groups.

Although the majority of people in the U.S. are vaccinated, many still grumble about it and refuse to get additional recommended boosters. So here’s yet another reassuring study published in The Lancet.

That 30-50% reduction in long Covid emerged from a powerful study of 10 million vaccinated and 10 million unvaccinated people in three European countries. I subscribe to New England Journal Watch, and I like how they interpreted this result further:

The large size of this study, inclusion of a never-infected comparison group, analysis of symptoms before the pandemic, and the study's statistical rigor provide strong evidence that COVID-19 vaccination lowers risk for long COVID. This protection is seen in all age groups, including young adults. Because young adults can develop long COVID, perhaps vaccine boosters should be recommended more strongly in this group.

Boldface emphasis added by me. I’ve consistently been advocating for this all along, and have been frustrated by thought leaders who narrowly consider the purpose of vaccination “just to prevent hospitalization and death.”

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*From my April letter:

Myocarditis and vaccines? Minimal worries at this point.

Also from the CDC: Oregon health officials investigated potential sudden cardiac deaths among young people after COVID-19 vaccination but found no clear association. They examined death certificates and vaccination records for individuals aged 16-30 who died from cardiac or undetermined causes between June 2021 and December 2022 and did not find evidence linking the vaccines to sudden cardiac deaths in this age group.

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A Norwegian study finds vaccination reduced long Covid by 40%, among other benefits

This study in The Lancet found that COVID-19 vaccines consistently prevent long COVID symptoms and post-COVID thromboembolic and cardiovascular complications across different age groups and underlying health conditions in the Norwegian population. It confirms the reproducibility and generalizability of previous findings from other countries.

Vaccines benefit kids, so keep them up to date, too.

A study from the CDC: During December, 2021–October, 2023, receipt of ≥2 doses of an original mRNA COVID-19 vaccine was 52% effective against pediatric hospitalization and 57% effective against critical illness related to COVID-19, when the last dose was received within the 4 months preceding hospitalization, but protection decreased over time.

These findings support existing recommendations that children and adolescents aged 5–18 years remain up to date with COVID-19 vaccination.

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*From my May letter:

Kids with long Covid can’t run and play as well. Objectively.

There has been a lot of gaslighting, trivialization, and dismissal of the potential harms of Covid in kids. Most seem to be doing pretty well after Covid, but many are not. Estimates for the incidence and prevalence of long Covid in kids range from about 1% if you check with the CDC… to 10 - 20% if you check with this recent study published in Pediatrics. That would be up to 6 million kids with some combination of:

…(lingering) cough, headaches, fatigue, and loss of taste and smell, new symptoms like dizziness, or exacerbation of underlying conditions. Children may develop conditions de novo, including postural orthostatic tachycardia syndrome, myalgic encephalomyelitis/chronic fatigue syndrome, autoimmune conditions and multisystem inflammatory syndrome.

A recent study in The Pediatric Infectious Disease Journal confirms that 90% of kids with suspected long Covid who underwent exercise testing had objectively impaired functional capacity (expressed by a low VO2 peak), signs of deconditioning, and cardiogenic inefficiency. This compared to just 10% of kids without the diagnosis of long Covid.

To me this shows that we should still be keeping kids up to date with recommended vaccines, not sending them immediately back to school when sick, and asking them to wear a mask when they return to school while still contagious with Covid to protect their teachers and friends somewhat. Maybe 7 days from the start of symptoms would be a decent thing to do.

The updated XBB vaccines were effective, although less so against JN.1. Bring on KP-2 for this fall?

A study published in the NEJM showed that the updated Covid vaccine (against XBB.1.5) that many of us received last fall, and that many over age 65 received a booster with this spring, worked fairly well… but with the following qualifications:

• Protection against infection waned faster than we would like.

• Overall benefit has been a bit less against the currently dominant coronavirus variant called JN.1.

Specifically, the updated shots from Moderna, Pfizer-BioNTech, and Novavax over a 5-month period from September 2023 to February 2024:

• Reduced infections by:

  • 52% after 4 weeks (but dropping to 44% when JN.1 became dominant)

  • 33% after 10 weeks

  • 20% after 20 weeks

• Reduced hospitalizations by

  • 67% (but dropping to 60% when JN.1 became dominant) after 4 weeks

  • 57% after 10 weeks

• Reduced deaths:

So bottom line on this one is that overall the updated XBB vaccines were effective, although less so against JN.1. The effectiveness was greater against hospitalization and death than against infection, and this waned moderately from its peak over time. This pattern is similar to previous years.

This study found lower rates of protection than a previous one I highlighted in the February edition of Covidlandia. I’ll quote myself, quoting the experts:

The updated XBB Covid vaccine, which only 22% of American adults received this fall/winter, provided approximately 54% protection against symptomatic SARS-CoV-2 infection when compared with not getting the updated vaccine.

This updated vaccine was specifically found to provide good protection against the JN.1 variant which has dominated for months, and has also worked well against other circulating lineages.

What’s more, the new updated vaccine continued to provide 49% protection out to 119 days studied after the shot (about 4 months and counting).

What’s next? The updated vaccines for fall 2024 will likely target JN.1, or maybe the related FLiRT variants KP.2 and KP.3, or whatever whack-a-mole trends upwards as the FDA advisory committee meets on June 5th this week!

But with KP.2 trending upwards quickly, I think this would be the best call right now. Anyone taking bets?

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*From my letter in June:

This month was light on vaccine studies that caught my eye. So instead I’ll throw in a quick bit about antiviral treatment:

Early use of antivirals linked to reduced risk of long COVID

A meta-analysis of nine observational studies published in the Journal of Infectionshowed that early use of an oral antiviral drug (like Paxlovid) reduced the risk of long Covid by 24%. Not amazing, but significant. And given the difficulty of diagnosing long Covid without an objective blood test, who knows how much higher that 24% would be if we did check objective markers like endothelial biopsies, before and after CTA scans of the coronary arteries, peripheral nerve biopsies, etc. I’m not suggesting we do these tests in primary care, but for research it would be interesting.

An article in CIDRAP about this meta-analysis states:

While antivirals have been approved to use in the acute phase of illness to prevent progression to severe disease in at-risk populations, the potential use of the drugs as a way to prevent long COVID has drawn recent attention. 

Really? C’mon. I started writing about this over two years ago. I’ve been following the zeitgeist, not listening to the thought leaders who strayed from the early evidence, and holding firm to my own belief that treating early with antivirals like Paxlovid to reduce viral loads by an order of magnitude should reduce some collateral problems. I even drew a picture of a fruit cake back in March, 2022 to illustrate this. I’ve also been long on using metformin, and that COVID-OUT trial I discussed last month showed a 40-60% reduced risk of long Covid when we are able to stomach the 2 week course of metformin pills.

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*From my letter last month in July:

No increase in birth defects with first-trimester Covid shots

If I were pregnant I would definitely stay up to date with recommended Covid vaccinations. Contracting Covid while pregnant increases the mother’s risk of severe disease, pregnancy complications, and preterm delivery among other problems.

A study published last month in JAMA Pediatrics found that mRNA vaccines given during the first trimester were not associated with an increased risk for major structural birth defects in babies.

This cohort study used electronic health data from 8 US health systems including 42,156 eligible pregnancies, with the findings supporting the safety of maternal Covid vaccination in the first trimester

Previously postmarketing vaccine studies have shown no excess risk for pregnancy complications after immunization.

~

A second study, also published last month in British Medical Journal (BMJ), showed that while mothers infected during their first trimester with SARS CoV-2 faced higher risks to their own health and for preterm labor, there was no increased risk of birth defectsin their babies. Reassuringly, in mothers who received a vaccination during their first trimester, there was no increase in birth defects related to vaccination in this study either. So mothers picked up protection from severe illness by getting a jab with no significant risk to their babies.

In that second study, investigators studied 343,000 liveborn singleton infants in Norway, Sweden, and Denmark who were conceived between March 2020 and February 2022 and were followed for at least 9 months after birth.

More evidence that vaccines reduced long Covid risks

A study published in The New England Journal of Medicine provides strong evidence that Covid-19 vaccines significantly reduce the risk of developing long Covid (LC). They used health records from the VA Department to build a study population of 441,583 veterans with SARS-CoV-2 infection between March 1, 2020, and January 31, 2022, and 4,748,504 non-infected contemporaneous controls.

Here's a summary of the risk reductions among vaccinated versus unvaccinatedveterans with Covid, arranged by variants. Recall that younger people and women have higher rates of LC, so these percentages are skewed towards older, male veterans and probably underestimate the actual rates for all adults:

1. Pre-Delta era (unvaccinated only because we didn’t have vaccines yet):

   • 10.42% developed LC

2. Delta era:

   • Unvaccinated: 9.51%

   • Vaccinated: 5.34%

3. Omicron era:

   • Unvaccinated: 7.76%

   • Vaccinated: 3.50%

Overall trends:

• The risk of LC decreased over time for both vaccinated and unvaccinated individuals.

• Vaccination provided significant protection against LC in both the Delta and Omicron eras.

• 71.89% of the decreased risk was attributed to vaccines, with the rest attributed to changes in the virus

Despite the overall decrease, the study concludes that the risk of LC remained substantial even among vaccinated persons infected during the Omicron era. It’s still worth being cautious when you can, to not catch a case gratuitously during waves, and to treat Covid infections to further reduce risk. And also to be realistic that living in a bubble sucks, so everyone needs to make their own risk/reward calculus, and be compassionate with themselves during illnesses.

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*From the letter in August:

This study published in the journal Influenza, looked at the effectiveness of the adapted XBB.1.5 COVID-19 vaccine in Europe from October 2023 to January 2024. The study estimated a vaccine effectiveness (VE) of 49% against SARS-CoV-2 hospitalization, with slightly higher effectiveness in those aged 80 and above compared to those 60-79 years old. The VE declined over time, from 69% in the first 29 days to 40% at 60-105 days post-vaccination. It should be noted that this incremental benefit builds on top of the already decreased risks we have with prior shots and infections.

And a different study published in the journal Vaccine found an 80% reduction in hospitalization among women who received a Covid vaccination during pregnancy. Pregnant women are at higher risk of Covid complications such as hospitalization, intensive care unit admission, invasive mechanical ventilation, and death. They are also at increased risk of pregnancy-related complications including preeclampsia and emergency cesarean delivery. Their infants are at higher risk of preterm birth or being stillborn.

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I don’t expect most people to read the next 50+ highlights, but I think there is power and knowledge in dropping them apples anyway. Many of these studies are observational. It’s good to call for RCT-level proof, but these studies are harder to do, especially with moving, mutating targets. It would be foolish to dismiss everything above and below simply based upon an unwavering fealty to RCTs and dismissal of everything else (like a lot of doctors writing on Substack do). I agree with Dr. Howard about this:

In an ideal world of fantasy, there would be large RCTs to answer every clinical conundrum. However, in the real-world, especially in a pandemic where both the population and the virus change rapidly and constantly, doctors have to make decisions all the time without “robust data” from pristine RCTs to guide our every action. I would further argue that telling people to accept repeated COVID infections, especially without the protection of an updated vaccine, is absolutely a decision.

And from that article he wrote about Covid boosters, here are at least 50+ studies showing updated vaccines and boosters have actually been helping. It’s a long list, so feel free to skim it so you get the gist:

“Indeed, there are many studies, including a randomized-controlled trial (RCT), which show COVID vaccines beyond the first two doses already helped many people, though they are not a panacea. Here are the booster studies I could find, excluding those that only measured antibody responses.

• Barda (2021): Vaccine effectiveness evaluated at least 7 days after receipt of the third dose, compared with receiving only two doses at least 5 months ago, was estimated to be 93% (231 events for two doses vs 29 events for three doses; 95% CI 88–97) for admission to hospital, 92% (157 vs 17 events; 82–97) for severe disease, and 81% (44 vs seven events; 59–97) for COVID-19-related death.

• Arbel (2021): Participants who received a booster at least 5 months after a second dose of BNT162b2 had 90% lower mortality due to Covid-19 than participants who did not receive a booster.

• Bar-on (2021): Across the age groups studied, rates of confirmed Covid-19 and severe illness were substantially lower among participants who received a booster dose of the BNT162b2 vaccine than among those who did not.

• Muhsen (2022): The results of this cohort study suggest that receipt of a fourth BNT162b2 dose conferred high protection against COVID-19 hospitalizations and deaths among long-term care facilities residents during a substantial Omicron variant surge, but protection was modest against infection.

• Thompson (2022): During both Delta- and Omicron-predominant periods, receipt of a third vaccine dose was highly effective at preventing COVID-19–associated emergency department and urgent care encounters (94% and 82%, respectively) and preventing COVID-19–associated hospitalizations (94% and 90%, respectively).

• Andrews (2022): Against hospitalization or death, absolute effectiveness of a BNT162b2 booster ranged from around 97% to 99% in all age groups irrespective of the primary course, with no evidence of waning up to 10 weeks.

• Menni (2022): Vaccine effectiveness for booster doses in 0–3 months after BNT162b2 primary vaccination was higher than 92·5%, and effectiveness for heterologous boosters after ChAdOx1 nCoV-19 was at least 88·8%.

• Abu-Raddad (2022): Booster effectiveness against Covid-19–related hospitalization and death due to omicron infection, as compared with the primary series, was 76.5% (95% CI, 55.9 to 87.5). BNT162b2 booster effectiveness against symptomatic infection with the delta (or B.1.617.2) variant, as compared with the primary series, was 86.1%

• Moreira (2022): A third dose of the BNT162b2 vaccine administered a median of 10.8 months after the second dose provided 95.3% efficacy against Covid-19 as compared with two doses of the BNT162b2 vaccine during a median follow-up of 2.5 months. 

• Klein (2022): Two doses protect against COVID-19–associated emergency department and urgent care encounters among children and adolescents. However, vaccine effectiveness (VE) was lower during Omicron predominance and decreased with time since vaccination; a booster dose restored VE to 81% among adolescents aged 16–17 years. Overall, 2-dose VE against COVID-19–associated hospitalization was 73%–94%.

• Regev-Yochay (2022): Vaccine efficacy was estimated to be higher for the prevention of symptomatic disease (43% for BNT162b2 and 31% for mRNA-1273)…Our data provide evidence that a fourth dose of mRNA vaccine is immunogenic, safe, and somewhat efficacious (primarily against symptomatic disease).

• Mallah (2022): A booster dose of COVID-19 vaccine increases the protection against SARS-CoV-2 infection and COVID-19 severity in the general population and in comorbid patients.

• Magen (2022): Relative vaccine effectiveness in days 7 to 30 after the fourth dose was estimated to be 45% (95% confidence interval [CI], 44 to 47) against polymerase-chain-reaction–confirmed SARS-CoV-2 infection, 55% (95% CI, 53 to 58) against symptomatic Covid-19, 68% (95% CI, 59 to 74) against Covid-19–related hospitalization, 62% (95% CI, 50 to 74) against severe Covid-19, and 74% (95% CI, 50 to 90) against Covid-19–related death. 

• Adams (2022): During the first six months of 2022 in the US, booster doses of a covid-19 vaccine provided additional benefit beyond a primary vaccine series alone for preventing hospital admissions with omicron related covid-19.

• Tenforde (2022): Bivalent booster doses provided additional protection against COVID-19–associated emergency department/urgent care encounters and hospitalizations in persons who previously received 2, 3, or 4 monovalent vaccine doses. Because of waning of monovalent vaccine-conferred immunity, relative effectiveness of bivalent vaccines was higher with increased time since the previous monovalent dose.

• Tai (2022): This study found that in a young, healthy, highly vaccinated cohort frequently monitored for SARS-CoV-2, booster vaccination was associated with a significant reduction in incident infections during the Omicron wave. 

• Ng (2022): Estimated mRNA booster effectiveness against severe COVID-19 was 87.4% with no evidence of waning up to 6 months after boosting, while the estimated 3-dose inactivated SARS-CoV-2 booster effectiveness against severe COVID-19 was 69.6%. Booster mRNA vaccine protection against severe COVID-19 was estimated to be durable over 6 months.

• Ridgway (2022): In a large US population, mRNA boosters were associated with decreased odds of hospitalization compared with the mRNA vaccine primary series alone, with the magnitude of the association attenuated with more time since the booster dose.

• Lauring (2022):  mRNA vaccines were found to be highly effective in preventing covid-19 associated hospital admissions related to the alpha, delta, and omicron variants, but three vaccine doses were required to achieve protection against omicron similar to the protection that two doses provided against the delta and alpha variants. 

•  McConeghy (2022): In this cohort study of 10 949 residents of 202 community nursing homes and 4321 residents of 128 Veterans Health Administration community living centers, booster vaccination was associated with significant reductions in SARS-CoV-2 infections, hospitalizations, and the combined end point of hospitalizations or deaths.

• Accorsi (2022):  These findings suggest that vaccination with 3 doses of mRNA COVID-19 vaccine, compared with being unvaccinated and with receipt of 2 doses, was associated with protection against both the Omicron and Delta variants, although higher odds ratios for the association with Omicron infection suggest less protection for Omicron than for Delta.

• Spitzer (2022): Among health care workers previously vaccinated with a 2-dose series of BNT162b2, administration of a booster dose compared with not receiving one was significantly associated with a lower rate of SARS-CoV-2 infection in short-term follow-up.

• Kelly (2022): In a US cohort of patients receiving care at Veterans Health Administration facilities during a period of Delta and Omicron variant predominance, there was a low incidence of hospitalization with COVID-19 pneumonia or death following vaccination and booster with any of BNT162b2, mRNA-1273, or Ad26.COV2.S vaccines.

• Surie (2022): Among immunocompetent adults aged ≥65 years hospitalized in the multistate IVY Network, a bivalent booster dose provided 73% additional protection against COVID-19 hospitalization compared with past monovalent mRNA vaccination only.

• Fleming-Dutra (2022): Among children and adolescents, estimated vaccine effectiveness for 2 doses of BNT162b2 against symptomatic infection decreased rapidly, and among adolescents increased after a booster dose.

• Grewal (2022): The findings suggest that compared with a third dose of mRNA covid-19 vaccine, a fourth dose improved protection against infection, symptomatic infection, and severe outcomes among long term care residents during an omicron dominant period. A fourth vaccine dose was associated with strong protection against severe outcomes in vaccinated residents compared with unvaccinated residents, although the duration of protection remains unknown.

• McConeghy (2022): In a large cohort of nursing home residents, receipt of a second mRNA COVID-19 booster dose during circulation of SARS-CoV-2 Omicron subvariants was 74% effective at 60 days against severe COVID-19–related outcomes (including hospitalization or death) and 90% against death alone compared with receipt of a single booster dose.

• Roberts (2022): COVID-19 vaccines were highly protective against infection and severe COVID-19 resulting in hospitalization, intensive care unit admission, or death. Administration of a booster dose significantly increased vaccine effectiveness against both outcomes.

• Gazit (2022): A fourth dose of the BNT162b2 vaccine appears to have provided additional protection against both SARS-CoV-2 infection and severe covid-19 disease relative to three vaccine doses. However, relative effectiveness of the fourth dose against infection appears to wane sooner than that of the third dose.

• Wei (2023): Overall vaccine effectiveness against death at 4 to 6 months after the third dose was greater than 90% for CoronaVac, BNT162b2, and the mixed vaccine schedule. While vaccines were generally estimated to be effective against severe outcomes caused by SARS-CoV-2 Omicron infection, this analysis found that protection in older patients was more likely to wane 6 months after the second dose. Hence, a booster dose is recommended for older patients to restore immunity.

• Lundberg-Morris (2023): Vaccine effectiveness against post-covid-19 condition for one dose, two doses, and three or more doses was 21%, 59%, and 73%, respectively.

• Finci (2023): Among Albanian healthcare workers, most of whom had been previously infected, COVID-19 booster dose offered improved VE during a period of Omicron BA.1 and BA.2 circulation. 

• Wong (2023): Among nursing home residents who were up to date with COVID-19 vaccination (most had received a bivalent vaccine), vaccine effectiveness against SARS-CoV-2 infection was 31.2%.

• Klein (2023): BNT162b2 protected children and adolescents against mild to moderate and severe COVID-19. VE was lower during Omicron predominance including BA.4/BA.5, waned after dose 2 but increased after a monovalent booster.

• Link-Gelles (2023): A bivalent mRNA booster dose provided additional protection against symptomatic XBB/XBB.1.5 infection for at least the first 3 months after vaccination in persons who had previously received 2–4 monovalent vaccine doses.

• Andersson (2023): Heterologous booster schedules are associated with increased protection against severe, omicron related covid-19 outcomes compared with primary course schedules and homologous booster schedules.

• Andersson (2023): Vaccination with bivalent BA.4-5 or BA.1 mRNA booster vaccines as a fourth dose was associated with reduced rates of covid-19 related hospital admission and death among adults aged ≥50 years. 

• Stecher (2023): Our results indicate an increased protective effect of a fourth dose against severe outcomes compared with a third dose, with decreasing effect with time since the last dose.

• Link-Gelles (2023): In this case-control study of COVID-19 vaccines and illness, VE associated with protection against medically attended COVID-19 illness was lower with increasing time since last dose; estimated VE was higher after receipt of 1 or 2 booster doses compared with a primary series alone.

• Lin (2023): Although the two bivalent vaccines were designed to target the BA.4–BA.5 subvariants, they were also associated with a lower risk of infection or severe infection with the BQ.1–BQ.1.1 and XBB–XBB.1.5 subvariants. The effectiveness was higher against hospitalization and death than against infection and waned gradually from its peak over time.

• Lin (2023): Vaccine effectiveness against severe infection resulting in hospitalization or death was 24.9% (95% CI, 1.4 to 42.8) for one monovalent booster dose and 61.8% (95% CI, 48.2 to 71.8) for one bivalent booster dose.

• Jang (2023): The 4-dose booster, irrespective of history of SARS-CoV-2 infection, was associated with higher protection against critical BA.5 infection, as shown in previous studies.

• Lewis (2023): Vaccine booster doses increased protection against COVID-19 hospitalization compared with a primary series. 

• Tartof (2023): A BNT162b2 BA.4/5 bivalent booster restored protection against a range of COVID-19 outcomes, including against XBB-related sublineages, with the most substantial protection observed against hospital admission and critical illness.

• Liu (2023):  The effectiveness of boosters against mortality wanes with time but a booster still provides substantial residual protection six months after receipt. Increasing population hybrid immunity is likely to reduce observed vaccine effectiveness as the pandemic progresses but COVID-19 boosters continue to provide significant benefits in mortality reduction, particularly in high-risk populations such as those aged 65+ years and those resident in aged care facilities.

• Hanberg (2023): A fourth dose of COVID-19 mRNA vaccine reduced the risk of SARS-CoV-2 infection and severe COVID-19 among patients with systemic autoimmune rheumatic diseases using DMARDs during the Omicron era.

• Piekos (2023): COVID-19 vaccination protects against adverse maternal–fetal outcomes, with booster doses conferring additional protection.

• Amir (2023): In adolescents aged 12–15 years, the booster dose decreased confirmed infection rates by 3.3 times (2.8–4.0) compared with in the internal control group. 

• Chemaitelly (2023): Boosters substantially reduced infection and severe COVID-19, particularly among individuals who were clinically vulnerable, affirming the public health value of booster vaccination.

• Tartof (2023): The BNT162b2 XBB1.5-adapted vaccine provided significant additional protection against a range of COVID-19 outcomes during a period when XBB sub-lineages were predominant but JN.1 was also co-circulating and rapidly increasing in prevalence. Older versions of COVID-19 vaccines offered little, if any, additional protection compared to the unvaccinated, including against COVID-19 hospital admission, regardless of the number or type of prior doses received.

• Jara (2023):  The overall adjusted effectiveness of a second mRNA booster shot is 88.2% (95%CI, 86.2–89.9) against ICU admissions and 90.5% (95%CI 89.4–91.4) against death. 

• Payne (2024): During September 2022–March 2023, receipt of bivalent mRNA COVID-19 vaccine was 47% effective in preventing thromboembolic events among immunocompetent persons aged ≥65 years and 51% effective among adults aged ≥18 years with end stage renal disease (ESRD) receiving dialysis, compared with receipt of the original monovalent vaccines alone.

Systematic reviews meta-analyses:

• Zhu (2022):The pooled results demonstrated a 71% (OR = 0.29, 95% CI = 0.17-0.48) reduction in SARS-CoV-2 infection rates among subjects who received a booster shot compared with those who did not receive a booster shot of coronavirus disease (COVID-19) vaccine. In addition, this analysis emphasized that during the period when the Delta variant was predominant, subjects who received the booster shot showed an 82% (OR = 0.18, 95% CI = 0.13-0.25) reduction in infection rates. Moreover, during the period of dominance of the Omicron variant, subjects who received the booster vaccination displayed a 47% (OR = 0.53, 95% CI = 0.35-0.81) reduction in infection rates. 

• Au (2022): For people with delta or omicron related infection, a two dose regimen of an adenovirus vector vaccine with one dose of mRNA booster was 77% (42% to 91%) effective against asymptomatic or symptomatic covid-19 infections, and a three dose regimen of a mRNA vaccine was 93% (76% to 98%) effective against covid-19 related hospital admission.

• Menegale (2023): Booster doses restored VE to levels comparable to those acquired soon after the administration of the primary cycle. However, 9 months after booster administration, VE against Omicron was lower than 30% against laboratory-confirmed infection and symptomatic disease.

• Xu (2023): The risk of SARS-CoV-2 infection, the risk of admission to the ICU, and the risk of death were all higher in the non-booster group than those in the booster group.

• Yang (2023): The efficacy of SARS-CoV-2 vaccines is higher for preventing severe infection and death than for preventing milder infection. Vaccine efficacy wanes over time but can be enhanced by a booster. 

• Xu (2023): Inactivated vaccine protection against SARS-CoV-2 infection was moderate, decreased significantly after 6 months following primary vaccination, and was restored by booster vaccination. VE against severe COVID-19 was greatest after boosting and did not decrease over time, sustained for over 6 months after the primary series, and more evidence is needed to assess the duration of booster VE. VE varied by variants, most notably against Omicron. It is necessary to ensure booster vaccination of everyone eligible for SARS-CoV-2 vaccines and continue monitoring virus evolution and VE.

• European Centre for Disease Prevention and Control (2023): Under the Omicron variant, effectiveness of EU-licensed COVID-19 vaccines in preventing any SARS-CoV-2 infection or mild disease is low and only short-lasting after primary immunization, but can be improved by booster vaccination. Vaccine effectiveness (VE) against severe COVID-19 remains high and is long-lasting, especially after receiving the booster vaccination.

• Mohammed (2023): VE against severe Omicron infection following the primary course was 63.6% (95%CI: 57.5–69.7%) at three months, decreased to 49% (95%CI: 35.7–63.4%) within six months, and increased to 86% after the first or second booster dose.”

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Conclusion

I wish you the best in making your decision and plans for the updated Covid shots. I’ve made mine. The CDC is not making stuff up as you can see just from the studies presented above. I don’t accept money, hot dogs, or even face to face time with drug representatives. All vaccines have potential side effects, but the science keeps watching for these, and the CDC, ACIP, and FDA weigh known risks against known benefits.

Me? I just want to be a good primary care doc. I want to err on the side of the evidence over the speculation.

Take good care. Spread the word and forward at will.