Welcome to episode 485 of The Whole View! This week, Stacy and Dr. Sarah break down the science behind Covid-19 boosters for adults.
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The Whole View, Episode 485: Covid-19 Boosters for Adults
Welcome to episode 485 of the Whole View! (1:20)
This episode is a continuation of Stacy and Dr. Sarah’s Covid-19 shows, so if you haven’t caught up yet, check out:
- 468: The Delta Covid-19 Variant
- 455: Covid-19 Vaccines – Real World Data and Updated Vaccine Studies
- 454: The J&J and AstraZeneca Covid-19 Vaccines
- 444: Covid-19 Vaccine Myths and FAQ Part 4
- 443: Covid-19 Vaccines Part 3 – Myths and FAQ’s
- 441: COVID-19 Vaccines Part 2 – Pfizer/BioNTech vs Moderna
- 440: COVID-19 Vaccines Part 1 – mRNA Vaccine Technology
- 425: Covid-19 FAQ Part 4
- 412: Covid-19 FAQ, Part 3
- 403: Stacy Has Covid-19, Now What?
- 401: Covid-19 NEW FAQ
Stacy was actually vaccine hesitant before those shows, but has since chanced her mind and is now scheduled to get her 3rd booster vaccine.
As a reminder, Stacy and Dr. Sarah are not medical professional, so it’s important to involve your primary care doctor in all your medical decisions.
I wanted to say I listened to every covid 19 vaccine podcast. It was so good. And I got j&j. I am so grateful for the research and thought and time y’all put into it to help give me peace of mind and educate myself. I was in bed sick for 7 days recovering from the vaccine. And I am interested in the booster. And I am wondering if y’all are going to do another podcast on it.
I am positive y’all probably got death threats which is just horrifying. But for folks like me who want to know the science balanced with a holistic mindset, it’s a true gift what you give to this holistic community. Okay I’m tearing up over here.
Yes I had a rough week recovering from the vaccine. And I know I needed to get it. And I don’t regret it. But there’s not much talk about the booster. Would love your research and findings. Thank y’all for the work you do. Truly. So so thankful.
Immunity and Covid-19 Boosters for Adults
Dr. Sarah starts by reviewing the data that went into the approval for boosters for everyone over 18 years old. (8:04)
The Ministry of Health in Israel, a country with one of the world’s highest vaccination rates, released raw data on vaccinations and infections from December 2020 to July 2021.
The ministry estimated that vaccine protection against both infection and disease had dropped from above 90% in the early months of its program to around 40% by late June. This decline could be due to the effects of the Delta variant.
To look more closely for evidence of waning protection, scientists at Kahn Sagol Maccabi in Tel Aviv — the research arm of Israeli health-maintenance organization Maccabi Healthcare Services — analyzed health records from more than 1.3 million people who were vaccinated between January and April 2021.
Those vaccinated in January and February were 53% more likely to test positive for SARS-CoV-2 during those four months than people vaccinated in March and April. The differences were even starker among the earliest and latest vaccinated.
Stacy and Dr. Sarah talked about the Delta variant at length in Episode 468.
The mRNA Vaccine Clinical Trials
On 28 July, researchers at Pfizer–BioNTech, who have pushed strongly for third doses, published data on the preprint server medRxiv showing that the vaccine’s efficacy against symptomatic disease had slipped from 96% to 84% after 6 months.
An April press release from Moderna put its vaccine’s efficacy at “greater than 90%” after half a year, compared to its original efficacy figure of 94%.
Possible reasons why Pfizer drops off faster:
- Moderna has a much higher dose (100 micrograms) than Pfizer (30 micrograms).
- The 4 weeks between shots vs. 3, may lead to longer-lasting immunity.
A CDC study of front-line workers found that the vaccines’ effectiveness at preventing infections dropped from 91% (in pre-delta times) to 66% after the delta variant became dominant.
But Is Immunity Actually Lower?
It’s actually hard to know from these data. Possible explanations outside of reduced immunity are that higher-risk people got vaccinated earlier.
There’s quite a bit of evidence that many of the conditions that predispose us to more severe covid (like immunocompromised and older age) also correlate with a less robust immune response to the vaccines.
Another is behavior. Before we knew about higher breakthrough infection rates with Delta, we took fewer precautions.
Higher breakthrough infection rates with VOCs like Delta can explain the data too.
What’s more, there doesn’t seem to be a drop-off rate in hospitalizations and death! And the vaccines are still very protective against hospitalization across all age groups.
A CDC study published in late September comparing the real-world effectiveness of all three vaccines at preventing hospitalization found Moderna was 93% effective, Pfizer was 88%, and J&J was 71%.
Do We Need Covid-19 Boosters for Adults?
So, the data on actually waning immunity is still preliminary and still debated among scientists. (15:00)
But, there are still some compelling scientific rationales for boosters!
A 3rd dose is likely needed for anyone whose immune system is underperforming, as Stacy and Dr. Sarah discussed in Episode 468:
It protects 80% against SARS-CoV-2 infection ≥7 days after 2nd dose of mRNA vaccine among people with IBD on immunosuppressive medication.
Also, it’s 59% effective against COVID-19 hospitalization among immunocompromised ≥14 days after 2nd dose of mRNA vaccine vs. 91% (CI 86-95%) without immune compromise.
Recipients of hematopoietic cell or solid organs transplant, patients under immunosuppressive therapy, asplenia, and chronic renal failure ) advanced kidney disease, dialysis, or nephrotic syndrome) are all considered immunocompromised conditions.
What About Those Who Are Healthy?
Even if you don’t have a health condition, there’s still some good rationale for getting a booster.
It gets ahead of waning protection, and the 10X increase in neutralizing antibodies means more protection against variants of concern.
Recall from Episode 468 that the antibodies we make when we’re vaccinated bind with different affinities to different variants.
So far, Moderna’s research on the different mRNA strand boosters shows that it’s more important to have more antibodies around to make up for that lower binding affinity than it is to have a booster shot made for a slightly different mRNA strand that aligns with VOCs more closely. This is true, at least with the current variants.
Not much is known about omicron yet, but Pfizer and Moderna are already working on boosters with its sequence JIC.
How Does the Third Booster Work?
Vaccination produces an initial surge in the number of immune cells churning out antibodies and other molecules, which slowly drop in num. ()
This leaves behind a small pool of long-lasting ‘memory’ B and T cells that patrol the body for future infections by that pathogen.
A booster causes antibody-making B cells to multiply, elevating the levels of antibodies against the pathogen once more.
In time, their numbers will dwindle again, but the pool of memory B cells left behind will be larger than before, leading to a faster, stronger response to subsequent exposures.
Boosters also promote a process called affinity maturation, in which ‘engaged’ B cells — those triggered by the vaccine — travel to the lymph nodes. Here, they gain mutations, making the antibodies they produce bind to pathogens more strongly, potentially enhancing their potency.
The numbers of memory B cells and antibody levels will eventually plateau with repeated boosting. But it is unlikely that such levels have been reached in people who have had the recommended regimen of COVID-19 vaccine or previous infection,
Scientific Evidence For Boosters
Clinical trials in covid-19 vaccines have confirmed this boost! (24:20)
Third doses of vaccines developed by Moderna, Pfizer–BioNTech, Oxford–AstraZeneca, and Sinovac prompted a spike in levels of infection-blocking ‘neutralizing’ antibodies when administered several months after the second dose. The increase is at least 10X!
For Pfizer, the durability of immunity looks better than after the initial 2-doses (no drop off after a month in Pfizer, for example), although this will be monitored.
But there are a few things to keep in mind!
It’s more critical for unvaccinated people to get the information they need to feel comfortable getting vaccinated than for most fully vaccinated people to get boosted.
Also, boosters are important for anyone at higher risk of severe covid or higher risk of exposure.
If you skip your booster, that dose isn’t going to be sent to a country that needs it.
Everyone is still considered fully vaccinated two weeks after their second dose in a two-shot series, such as the Pfizer-BioNTech or Moderna vaccines, or two weeks after a single-dose vaccine (J&J/Janssen vaccine).
Vaccine Immunity IS Better Than Natural Immunity
Among COVID-19–like illness hospitalizations among adults aged ≥18 years whose previous infection or vaccination occurred 90–179 days earlier, the adjusted odds of laboratory-confirmed COVID-19 among unvaccinated adults with previous SARS-CoV-2 infection were 5.49-fold higher than the odds among fully vaccinated recipients of an mRNA COVID-19 vaccine who had no previous documented infection (95% confidence interval = 2.75–10.99). Source (32:27)
That’s kinda a big deal. Dr. Sarah predicted this could be the case back in Episode 441!
Are Covid-19 Boosters for Adults Safe?
So far, reactions reported after getting a booster shot are similar to those of the two-shot or single-dose primary series. (39:53)
Clinical trial data show that homologous COVID-19 booster doses (utilizing the same vaccine product for the primary series and booster dose) increase the immune response against SARS-CoV-2 and have an acceptable safety profile for all FDA-approved or FDA-authorized COVID-19 vaccine boosters.
- BNT162b2 [COMIRNATY® (COVID-19 Vaccine, mRNA)] Booster (Third) Dose
- Safety and Immunogenicity of a 50 μg Booster Dose of Moderna COVID-19 Vaccine
- Booster Dose of Janssen COVID-19 Vaccine (Ad26.COV2.S) Following Primary Vaccination
Also, there were no serious adverse events or deaths from the boosters!
The side effect profiles are similar for the 3rd shot. The safety profile looks the same too, so very rare cases of myocarditis and severe allergic reactions with the mRNA vaccines, rare cases of Guillain-Barre syndrome, and immune thrombotic thrombocytopenia with the adenovirus vector vaccines.
Immune Thrombotic Thrombocytopenia
Potential risks of a Janssen COVID-19 booster include the rare risks of Guillain-Barré Syndrome (GBS) and thrombosis with thrombocytopenia syndrome (TTS). (44;10)
Based on data after receipt of a Janssen COVID-19 primary dose, the group at the highest risk for GBS are men aged 50–64 years, and the group highest at risk for TTS are women aged 18–49 years.
Women aged 18–49 years should be made aware of the increased risk for TTS and the availability of mRNA COVID-19 vaccines for use as a booster dose.
People who developed TTS after their initial Janssen Vaccine should not receive a Janssen booster dose. Considerations for Janssen COVID-19 Vaccine can be consulted for additional information.
We talked about this a little in episode 443 and our first Patreon Q&A, but there’s more data now, so let’s talk about this a bit more. (50:35)
Potential risks of an mRNA COVID-19 booster dose include the rare risks of myocarditis and pericarditis.
Based on data after mRNA COVID-19 primary series, the group at the highest risk for myocarditis and pericarditis are males aged 12-29 years.
Accumulating evidence from multiple sources suggests a higher risk for myocarditis following Moderna than Pfizer-BioNTech vaccination; however, it is not possible to directly compare the risk in persons aged 12–17 years old because Pfizer-BioNTech is the only COVID-19 vaccine authorized in this age group. No data on this after booster since it’s such a rare event
The risk of myocarditis from covid-19 infection is much higher than the risk from vaccination.
Researchers analyzed the records of healthcare organizations that cover a fifth of the US population. They found that, during the first 12 months of the pandemic, males aged 12 to 17 were most likely to develop myocarditis within three months of catching covid-19, at a rate of about 450 cases per million infections.
According to figures from the US Advisory Committee on Immunization Practices, this compares with 67 cases of myocarditis per million males of the same age following their second dose of a Pfizer/BioNTech or Moderna vaccine.
Researchers added together cases after first and second doses to reach a total of 77 cases per million in this male age group triggered by vaccination, a sixth seen after infection. Source
The Science Behind It
In this vaccination analysis, the vaccinated and control groups each included a mean of 884,828 persons. Vaccination was most strongly associated with an elevated risk of myocarditis (risk ratio, 3.24; 95% confidence interval [CI], 1.55 to 12.44; risk difference, 2.7 events per 100,000 persons; 95% CI, 1.0 to 4.6), lymphadenopathy (risk ratio, 2.43; 95% CI, 2.05 to 2.78; risk difference, 78.4 events per 100,000 persons; 95% CI, 64.1 to 89.3), appendicitis (risk ratio, 1.40; 95% CI, 1.02 to 2.01; risk difference, 5.0 events per 100,000 persons; 95% CI, 0.3 to 9.9), and herpes zoster infection (risk ratio, 1.43; 95% CI, 1.20 to 1.73; risk difference, 15.8 events per 100,000 persons; 95% CI, 8.2 to 24.2).
SARS-CoV-2 infection links to a substantially increased risk of myocarditis (risk ratio, 18.28; 95% CI, 3.95 to 25.12; risk difference, 11.0 events per 100,000 persons; 95% CI, 5.6 to 15.8) and of additional serious adverse events, including pericarditis, arrhythmia, deep-vein thrombosis, pulmonary embolism, myocardial infarction, intracranial hemorrhage, and thrombocytopenia.
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