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COVID-19 Boosters: Why and When

“We can’t boost our way out of this pandemic with the present generation of vaccines."

- John P. Moore, Ph.D., Professor of Microbiology and Immunology, Weill Cornell Medical College


“But the underlying issue remains: The U.S. does not have a strong, coordinated vaccination plan.”

- Katherine J. Wu, Ph.D., staff writer, The Atlantic



The Biden Administration recently announced plans to begin a COVID-19 booster campaign with reformulated vaccines in September. This leaves many of us with questions about whether and when to get boosted. In this Germ Gems post I explain why boosters are recommended, and address the need to be up to date on all COVID-19 vaccinations. Bottom line: get your booster shots.

Why are boosters needed? The development and distribution of effective and safe COVID-19 vaccines within one year’s time of the onset of the pandemic was (and still is) miraculous. But SARS-CoV-2, the cause of COVID-19, has proved to be a master at developing mutations of its spike protein allowing it to escape neutralizing antibodies that are produced by vaccination. These new mutations drive the pandemic’s waves and surges. To fight these mutations, booster doses of vaccines are needed.


Omicron BA.5 subvariant is the SARS-CoV-2 mutant that’s behind most of the current global surges. This subvariant is extraordinarily contagious. A recent estimate of its contagiousness (R0) is 17 (i.e., on average, one infected person can be expected to transmit the virus to 17 others) compared with measles virus, which is considered the most contagious of all viruses that has an R0 of 13. In recent studies, BA.5 was found to be the most immune-evasive variant to date. Its spike protein binds to the receptor for the virus on human cells six times better than the original coronavirus strain found in 2019.


Nonetheless, a recent study published in Science showed that booster shots provide substantial protection against severe disease even against the new subvariants. This is the main reason to get boosted: to protect yourself from dying or needing hospitalization.


Check your vaccination status: are you boosted? It is important to emphasize that the COVID-19 vaccines do provide substantial protection against severe disease, hospitalization and death. Recent studies also show that vaccines reduce the risk of long COVID. Therefore, everyone who is eligible should be fully vaccinated and up to date with vaccines. What does that mean? The Centers for Disease Control and Prevention (CDC) provides the following guidance.

First, COVID-19 primary series vaccines are recommenced for everyone ages 6 months and older, and COVID-19boosters for everyone ages 5 years and older, if eligible. Adults 50 years and older should receive a 2-dose primary series separated by 4-8 weeks and 2 booster doses. The first booster dose should be administered at least 5 months after completion of the primary series and the second booster dose at least 4 months after the first booster dose.


People who are moderately or severely immunocompromised should follow specific recommendations for COVID-19 vaccines, including boosters. (The conditions associated with a compromised immune system are provided in the “CDC’s Vaccines & Immunizations: Guidance & Recommendations”.)


You are considered fully vaccinated two weeks after you get a second dose of an mRNA COVID-19 vaccine, two weeks after you get a second dose of the Novavax COVID-19 vaccine, or two weeks after you get a single dose of the Janssen/Johnson & Johnson COVID-19 vaccine. You are considered up to date with your vaccines if you’ve received all recommended doses of COVID-19 vaccines, including boosters.


The CDC estimates that about 84% of those ages 5 and older have received at least one COVID-19 shot, and 72% are considered fully vaccinated with the initial vaccine series. But only 48% have received one booster dose, and only 31% of those ages 50 and older have received a second booster dose so far. Therefore, a majority of American adults aren’t up to date on their vaccinations. Are you?


Which booster should I get? The CDC recommends that individuals get an mRNA vaccine booster rather than a booster with either a protein- or viral vector-based vaccine. For those who received Johnson & Johnson’s one dose vaccine, “mixing and matching” with a booster of either the Moderna or Pfizer-Bio-NTech mRNA vaccine is allowed. Whether the Moderna or Pfizer booster is more effective is unknown, but a study published in Journal American Medical Association in May suggests that the Moderna vaccine elicits a stronger immune response in individuals who are immunocompromised.

When should I get boosted? Both Moderna and Pfizer-Bio-NTech are working on producing bivalent vaccines that cover the original SARS-CoV-2 virus, plus the BA.4 and BA.5 subvariants and have received hefty federal government contracts to achieve this goal by mid-October. With the recent White House announcement that these vaccines will be available in September, it appears both Moderna and Pfizer are ramping up production.


Opinions differ between getting boosted now with an available mRNA vaccine or waiting until the new bivalent vaccine is available and getting jabbed then (be it in September or later). So what should you do if you currently need a second booster to bring yourself up to date on your vaccinations?


I favor the “sooner the better” argument, that is, get boosted now and if needs be get another booster when the bivalent vaccines are available either in late fall or early winter. Although we may not be able to vaccinate our way out of the COVID-19 pandemic with the present generation of vaccines, getting yourself properly boosted increases your odds of making it out of this pandemic. To me, it’s a no-brainer.

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Main Page images courtesy of Shuxian Hu, MD. Dr. Hu is a scientist in the Neuroimmunology Research Laboratory at the University of Minnesota.

 

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