This week (on March 29, 2022), the FDA and CDC released authorization and guidance for a second booster vaccination against SARS-CoV-2, the virus that causes COVID-19. Do we really need to roll up our sleeves again?
The new guidance, both in terms of process and recommendations, differs significantly from previous guidance. For example, no advisory committees from FDA or CDC met to review new data. There was no public discussion or release of information. Instead, an executive decision was made by FDA to authorize the vaccine and CDC to recommend the vaccine, with information released by press release to explain the rationale. Moreover, only the mRNA vaccines from Pfizer/BioNTech and Moderna were recommended. Lastly, only people age 50 and up, or immunocompromised individuals, are recommended to get this second booster shot.
So if you are in good health, and under 50 years of age, there is no authorization to receive a second booster dose.
What is the basis for this recommendation?
Likely it is based on data from Israel, where the government has been much more forward about permitting and giving additional doses. One study, an as not yet peer-reviewed “preprint”, showed benefit from both illness (decreased by factor of 2) and by severe illness (decreased by factor of 4). However, this was not a randomized, double blind, placebo-controlled trial, the gold standard of medical evidence. There were some differences between the control group (only three doses of vaccine) and intervention group (fourth dose). A second study, also not peer reviewed, showed similar data. Both studies looked just at the Pfizer/BioNTech vaccine. Selection bias is a thing, it may be that more careful people were more likely to get the fourth dose.
Nevertheless, the data sets were large (1,138,081 participants in the first study, and 503,405 participants in the second study) and results were fairly striking.
So does it help? Certainly if one is over 60 years of age, the data looks pretty good. FDA and CDC tacked an extra 10 years of eligibility (down to 50 years of age), in recognition that many people may be unaware that they have “silent” comorbid conditions, such as diabetes mellitus, uncontrolled hypertension, and mild obesity.
Are there downsides to getting an extra dose? Neither study showed significant adverse reactions in people getting a fourth dose of vaccine.
While some may choose to wait beyond four months, perhaps because they were recently infected during the Omicron wave (recovery from infection may be considered a vaccination of sorts), or because they don’t want to get one “too early” before another surge, I plan to get mine soon.
But which one? I have had three of the Pfizer/BioNTech vaccines. I would like to get the Moderna, if available. There may be some data that “mix and match” of vaccines (also called “heterologous boosting”) provides slightly better immunity than just sticking with the same vaccine. On the other hand, I have tolerated the Pfizer/BioNTech vaccine reasonably well, so I suppose there may be a small risk of adverse reaction with a different vaccine.
We don’t know if another wave is coming, and whether it will be milder than what we just went through. We do know that immunity wanes over time. Previous coronavirus research, prior to COVID-19, showed that immunity lasted a year or so. SARS-CoV-2 immunity wanes around the same time period; maybe quicker if from vaccination than from recovery from infection.
We won’t know if this pandemic is over—until it is over!
My last dose of vaccine was five months ago. I’m ready for another dose of vaccine now.
To boost (again), or not to boost . . .
Thanks, Peter. I always like to here your expertise.
Thanks Peter. I so value your expertise, research based data and input.