Why I’m skeptical of boosters for all.
I don’t care what my antibody levels are if they’ll keep me out of the hospital.
Today, the White House Covid-19 task force announced plans to offer boosters to Americans over 18 years old who are more than 8 months out from their second dose of either a Pfizer or Moderna mRNA vaccine. The rollout could begin as soon as September 20th.
I remain a staunch supporter of vaccination. The vaccines keep people of all ages out of the hospital and prevent almost all fatalities. They continue to do so. While some data show that vaccines may be offering slightly less protection in preventing hospitalization and death as a result of waning immunity and the Delta variant, the vaccines have been holding up remarkably well. Nothing I’ve seen suggests that a boost for the general population will drastically decrease rates of severe disease, hospitalization, and death—at least not yet. Those are the outcomes that matter in terms of ending this global emergency.
The basis of this new policy appears to be concerns that protection provided by the vaccine wanes over time and that vaccine-derived antibodies are less effective against the Delta variant primarily in preventing mild and moderate illness. The belief is that a 3rd dose will address this. The data supporting this policy are that; 1) antibody levels fall over time; 2) higher antibody levels correlate to higher vaccine effectiveness; 3) higher antibody levels are needed to prevent illness caused by the Delta strain; and 4) 3rd doses of mRNA vaccines boost antibody titers by 10-fold or more.
All of that may be true. But it has yet to be shown to correlate to large changes in serious outcomes. Yes, preventing mild to moderate illness is something. But it’s not what we’ve been hammering home as the purpose of vaccinations for months now: that the vaccines prevent the terrible outcomes associated with this disease. Patients with mild and moderate disease do not require oxygen, for example. They do not require medications like steroids or other treatments that have been shown to improve outcomes. Mild and moderate Covid-19 illnesses can be profoundly uncomfortable and inconvenient. But in most cases, they do not represent true medical emergencies.
You may be asking, what’s the harm of boosting? Why not decrease mild and moderate illness and spread, if we have the resources to do so? If there were no potential harms, then yes, this would simply be a question of logistics and policy. But there are two categories of potential harm to consider that I fear have not been: individual and societal harms.
At the individual level, we need to know the side effect profile of a 3rd dose, especially in younger people. Until now, the benefits of vaccination have far outweighed the potential side effects. That has even been true in children, who appear to be the most likely to have notable, if rare, risks from the vaccines while being the least likely to benefit from them. But what would a 3rd dose do for healthy young adults, for example? As in teens, a small but detectable number of young adults have developed an inflammatory condition of the heart called myocarditis after vaccination. So far, almost all pediatric cases and a majority of adult ones have been mild. Will that hold true with the 3rd dose? Will rates skyrocket? Will the cases that do occur be equally mild or will they be serious? We don’t know. What if a far worse variant comes along in the fall or winter and we need to vaccinate against that? Would a 4th dose be so harmful to me that it is not safe? We’re rolling the dice here, when both the upsides and downsides seem uncertain.
The societal harms must also be considered. While the talking points are that we can “do everything,” the reality is that rolling out boosters will make it harder to get more people their first doses, both in the United States and abroad. Offering boosters to healthy Americans is all but guaranteed to exacerbate vaccine inequity.
That said, I support the policy of offering third doses to people with compromised immune systems or who carry other substantial risks. The best data we have indicate that two doses of the mRNA vaccines simply do not render immunocompromised people fully vaccinated against Covid-19. So, administering 3rd doses of the vaccines to immunocompromised people should not be thought of as “boosting” their vaccination, but rather, completing their initial vaccine series such that they are truly “fully” vaccinated. Being fully vaccinated is what matters. So far, most of us need two mRNA doses to achieve that, while the immunocompromised need three doses.
What’s unusual here is that a policy is being rolled out before we have the safety data we need. We can’t do a side-by-side assessment of the risks and benefits if that information is not available. We need to hear from the Center for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP). We need troves of data that come from public ACIP meetings and FDA reports.
From a messaging perspective, I also worry that telling people who are fully vaccinated that they now need a third dose could undermine the confidence of those who have yet to be convinced to have a single one.
If the government or researchers produce data demonstrating that a third dose enhances protection from serious disease and critical illness—or impressively limits breakthrough infections from being contagious to others at higher risk including those not yet eligible to be vaccinated—then yes, I’ll line up for one. But so far, I just have not seen data that leads me to that conclusion. I hope that by September 20th, I’ll be able to make a more informed call.
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