COVID-19: Will We Need Boosters or Not?


Apparently, I was not the only one to think Pfizer’s CEO Albert Bourla was out-of-line for his recent statements stating that people will need COVID-19 vaccine boosters on an annual basis.

There are two different trains of thought:

  1. Annual boosters will be necessary. Bourla was quoted on April 1, 2021 saying this.
  2. Once people have been infected (or vaccinated), subsequent infections will be cyclical (i.e., every other year) and not be as severe. Hence, most people will not need boosters.

Everything depends on reinfection. How long after an initial infection or vaccine does reinfection occur AND how severe does the reinfection tend to be? Dr. Fauci said on April 19 that we won’t likely know until later this summer or fall whether “break-through infections” (we are reading this as “reinfections”) will necessitate supplemental vaccine boosters. Like the other 4 common cold coronaviruses that nearly all of us have had many times throughout our lives, we will all be infected with COVID-19 again and again (as we have described). There are now 5 common cold coronaviruses, and we know that the earlier four cycle every other or every 3rd year.

Note that once we get infected or receive the COVID-19 vaccine, we have some immunity, and at some point in the future, we will all get reinfected.  Experts are suggesting that subsequent COVID-19 infections will tend to be much milder. When COVID-19 recycles, will the overall severity be such that a booster vaccine is needed? Although an individual’s IgG antibodies will wane, there is some immune memory and T cell mediation. We are still in the first “cycle” for COVID-19, as evidenced by the recent 4th “wave” of infections. The reason the FitzTS team is still calling this the 1st cycle, is because reinfections have not started to widely circulate. 

Recent evidence discussing reinfection:

  • As we published in our Jan. 2021 COVID-19 Reinfection blog, reinfection was very rare at the time. Here we are 14+ months into the pandemic, and COVID-19 reinfection remains extremely rare. On April 12, 2021, CIDRAP published that prior infection cuts the risk of reinfection by 84% (at 7 months).
  • March 27, 2021, The Lancet published the results of a very large Danish study. It showed previous COVID-19 infection protection against reinfection for 80.5% of people (in a time frame ~6 months). Though this dropped to 47.1% in people aged 65+.
  • The UK’s SIREN study also finds reinfection to be rare. The immune response from past infection is ~83% effective for preventing reinfection (for at least 5 months). Their data suggests that “natural immunity might be as effective as a vaccination”.
  • The SIREN study also showed that reinfections occurred in fewer than 1% of its’ 6600 participants.
  • A March 10, 2021 FORBES article brilliantly laid out a description of how natural immunity fades over time (comparing the original SARS2 vs. UK Variant B.1.1.7 vs. B1351 called the P.1 variant). Brazilian studies show the P.1 variant is ~1.4 – 2.2 times more transmissible than the original SARS2 strain.
  • Those who experience a mild or asymptomatic case will have less rigorous immune against reinfection (making them more susceptible).

Evidence-based Q&A regarding COVID-19 vaccines:

1. If someone has already been infected with COVID-19, should they still get vaccinated?

Yes. (Several members of my family members already had COVID-19, and yes, they received a vaccine even though they likely already have circulating antibodies). Rationale:

  1. Immunity wanes over time (check out our Immunity post).
  2. As long as COVID-19 is still infecting scores of people and is a public health risk, more immunity is a good idea.
  3. The good news is that prior COVID-19 infection AND the vaccine result in a higher antibody response than never having been infected.
  4. Reinfection with COVID-19 will happen at some point. An April 12, 2021 CIDRAP post indicated that prior COVID-19 infection was 93% effective at preventing symptomatic disease at 7 months. We just don’t know how severe cycles 2, 3, etc., will be.

2. Should younger and/or healthy adults get COVID-19 vaccine?

  1. Yes. This is because the disease is still widely circulating and is a public health risk. Young adults are twice as likely to transmit the virus. We believe it is extremely selfish to only think about oneself and run the risk of becoming a COVID-19 host and infecting others, particularly high-risk people. In Minnesota, I have noticed a trend of younger COVID-19 deaths. The new variants are not only more infectious, but seem to be more responsible for severely infecting and killing younger cohorts. This is a serious problem in Brazil, where most ICU patients are now <40.
  2. Note that no vaccine is 100% effective. Our at-risk friends and family should not be placed at risk simply because Dr. Rand Paul doesn’t think healthy adults should be vaccinated.

3. Are the COVID-19 vaccines safe? 

  1. Yes. All vaccines carry a risk of anaphylaxis, and the adenovirus COVID-19 vaccines (J & J, AstraZeneca) appear to carry an increased risk for rare blood clot disorders in women <50. We expect adenovirus vaccines to be approved and limited to certain patient cohorts.
  2. The risk of having a blood clot in the brain (CVT) is 8-10x higher in people who have been infected with COVID-19 than in those vaccinated.

4. Should children receive the vaccine?

  1. Right now, the Pfizer vaccine is limited to ages 16+ and the Moderna vaccine to ages 18+, although both are conducting clinical trials for younger ages.
  2. Prior to the B.1.1.7 variant, prepubescent children were getting infected at only 30% the rate of adults. This has changed. Increasing percentages of children are getting COVID-19, and infections have reignited across the country.
  3. Up until February 2021, we didn’t think it would be necessary to vaccinate children <12, as they did not tend to get severe cases, and they would build up immunity naturally. However, with the potential for further severe variants, we are rethinking this - especially in light of the Brazilian P1 variant that is a game-changer. 

In summary, we are glad that Pfizer, Moderna and other manufacturers are testing booster doses with variants, but think it is far too early to suggest these will be an annual thing. It is difficult enough to persuade the ~30% of the population who are hesitant about getting the COVID-19 vaccine to get one dose, but then to tell them that they will need more! It may make far more sense for an evidence-based, stratified risk algorithm to be used to determine who could/should get a COVID-19 booster and when.

Kevin Fitzpatrick, Fitzpatrick Translational Science

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