As Delta variant spreads, Americans wonder about vaccine booster

We are witnessing a rapid spread of the delta variant and a surge of new coronavirus infections. This occurs predominantly in those who are unvaccinated, but the variant is also arising as breakthrough infections (albeit mostly mild) in vaccinated individuals.

The unvaccinated may ask whether they should now get vaccinated to protect themselves and their families. Meanwhile, some who have been vaccinated wonder whether a booster shot is in order, sooner rather than later, especially given the rise in the delta variant. The answer is not yet clear. Data from Israel, the U.S. and elsewhere suggest that the current COVID-19 vaccines offer less protection against the delta variant than earlier versions of the virus. Early reports from Pfizer support the effectiveness of a booster shot against the delta variant while a review of safety data is pending. In the meantime, we must avoid jeopardizing the effectiveness of the first vaccine doses against original variants as well as the delta variant. The timing and efforts become a balancing act. What has been glaringly clear throughout the pandemic is the need to trust and follow the science in real-time. That means, in part, don’t jump the gun and make assumptions. Yet, it also means making the most informed public health decisions possible at any given moment.

When it comes to the COVID-19 vaccine the important premise in medicine is to first do no harm. Regarding potential vaccine side effects, therefore, we must recognize that the vast majority have had mild to moderate symptoms in response to the two-dose regimen of either Pfizer/BioNTech or Moderna. Associated arm pain, fatigue, general body aches, and low-grade fever are temporary and self-limited. Nonetheless, there is justifiable concern about the safety of a third dose. In addition, giving a third dose of a vaccine does not always guarantee a boost in one’s immunity. This needs to be studied thoroughly before a third dose becomes routine practice for otherwise healthy individuals. Furthermore, certain age and risk groups may benefit more from a boost than others. We suspect that those who are immunocompromised, elderly, with preexisting conditions such as obesity and chronic lung or heart disease and diabetes will be early recipients for a booster shot. Again, it is a balancing act, not just of timing with data available, but of weighing the risks and benefits.

Despite this speculation, we currently lack a clear metric that indicates who needs a boost and when. In this regard, there is a focus on the relatively simple test to measure antibodies to the spike protein of the virus. We know that the current generation of COVID-19 vaccines induce that antibody response in our blood. This assay, however, is variable and not directly predictive of whether an individual either has or retains a protective immune response. Nuanced and specific measurements of neutralizing antibodies, as well as T-cell studies, may more readily determine one’s degree of immunity; right now, there is no definitive indicator of protection from COVID-19. Developing and employing a simple blood test titer, as we have for other viruses like Hepatitis B, would be helpful to guide the potential need for a booster shot.

In the meantime, currently available data from the Centers for Disease Control and Prevention (CDC) and elsewhere indicate a high order of protection provided by a full vaccination with the Pfizer or Moderna shots against severe illness, hospitalization and death, for a large majority of those vaccinated — even against the delta variant, which is far more transmissible and appears to be more likely to cause severe illness in the unvaccinated. If you are fully immunized, you are far less likely to transmit the virus, including the delta variant.

As Lawrence Gostin, founding O’Neill Chair in Global Health Law and faculty director of the O’Neill Institute for National and Global Health Law at Georgetown University, explains, we must address the paucity of worldwide vaccine distribution. Wherever vaccinations are sparse, due to either vaccine refusal or lack of availability, as is dramatically the case in Africa and India, new variants are at liberty to emerge, thereby testing the range of the current vaccine regimens. On SiriusXM’s “Doctor Radio” this week, CDC director Rochelle Walensky responded to Gostin’s concerns that the United States is one of the few countries with a surplus of vaccines, which we should be sharing with the world.

The bottom line is that while concerns about our own vaccines wearing off are legitimate, patience is in order until the science is fully performed on this inquiry. Plus, we must remember that we are part of a universal “herd.” Refusing the lifesaving shots of the current regimens available or, in many places of the world, being unable to access them must both be resolved before, or at the very least in concert with, the question of booster administration.

What’s the answer, then, of whether to boost or not to boost and when to administer this third dose? The growing data that the vaccine’s immunity may be waning over time, especially in higher-risk groups, combined with the widespread consequences of the delta variant, is moving us in the direction of boosters for those most vulnerable, even in the absence of a definitive measurement of what precisely constitutes protective immunity against COVID-19. Whether or not this is premature, we turn to lessons from science and leadership in history. Those precedents teach us elements of vaccine science and practice that may remain undetermined even as we apply principles to reduce disease. Gen. George Washington arranged to vaccinate the Continental Army against smallpox in 1777 in Philadelphia when next to nothing was known about either viruses or immunity. What was known was that a first-generation smallpox vaccine significantly reduced mortality from that dreaded disease. By 1778, Washington’s vaccination campaign was considered a success; thousands of his troops had avoided contracting the deadly disease. Similarly, the proper scientific and humane decisions in the current pandemic around boosters involve balancing the known and the most likely paradigms based on current evidence, historic precedent and scientific understanding, along with the calculating of risks and benefits both individually and globally. While Israel just authorized booster shots for the elderly, the current scientific momentum in the U.S. appears to be moving in that direction too, but we aren’t quite there yet.

Mark C. Poznansky, M.D., PhD., FIDSA, is director of the Vaccine and Immunotherapy Center, Infectious Diseases Division, of Massachusetts General Hospital and professor of medicine at Harvard Medical School.

Marc Siegel, M.D., is a professor of medicine and medical director of Doctor Radio at NYU Langone Health. He is a Fox News medical correspondent and author of the new book, “COVID; the Politics of Fear and the Power of Science.”

Jacqueline A. Hart, M.D., director of the Bassuk Center on Homeless and Vulnerable Children, Families, and Youth, contributed to this article.