Winning the War on COVID Requires a Complete Understanding of Immunity. So Why Aren’t We Demanding It?

Less than a year into the vaccine rollout, regulators and policymakers are making important decisions about boosters and the next phase of COVID-19 vaccinations.

After all the recent hearings on boosters, one thing is certain: We are lacking critical US population-based information to answer the questions we are all asking. How long do vaccines provide protection? How effective are current vaccines against new variants? Does everyone need a booster, and if so, when?

As the virus becomes endemic globally, these persistent questions can only be answered by understanding the comprehensive adaptive immune response — including both B cells, which produce antibodies, and T cells, which attack virus-infected cells. This two-pronged data is needed to truly understand the enemy we are fighting. We have the tools to answer these critical questions, but we are not deploying them all in full force. What are we waiting for?

Historically, antibodies have been used as the main tool to assess vaccine response because they are well-understood and easy to measure. But in the wake of SARS-CoV-2 variants and breakthrough infections, and with national-level data, it’s clear that antibodies don’t tell the full story.

Antibodies work by binding to a very specific part of the virus to prevent it from entering healthy cells. When COVID variants, like delta, cause that part of the virus to change shape, the ability of vaccine-induced antibodies to prevent the virus from entering a cell is diminished. In contrast, T cells “see” and respond to many parts of the SARS-CoV-2 virus, both on and outside the spike protein. Even as the virus continues to mutate, the broad T-cell response retains the ability to recognize and kill infected cells and supports the production of antibodies.

This critical layer of durable protection provided by T cells must be better understood as vaccine efficacy wanes and boosters are in question. Data is mounting about the critical role that T cells play in protecting us from COVID — just as they do in other serious viruses including the flu, respiratory syncytial virus and SARS-CoV-1. How can we ensure that T cells are studied as equally and thoroughly as antibodies? The technologies exist, and we need to make a commitment to use them.

All vaccine manufacturers should measure both parts of the adaptive immune response — both T cells and antibodies — in their large studies to understand how our immune response changes over time, especially since we know variants are here to stay. Additionally, U.S. regulatory agencies should require T-cell assessment in addition to antibody assessment in all COVID-19 vaccine and drug development trials.

Large-scale studies must assess both parts of the adaptive immune response to the vaccines over time, ideally organized and funded by the U.S. government. We should be taking the lead on generating our own data to inform U.S. vaccination policies. The tools and resources to collect the data that should guide the decisions facing our society are readily available now and we can’t wait any longer.


Amy Abernethy, M.D., Ph.D. is president of Verily’s Clinical Studies Platforms and former principal deputy commissioner for the Food and Drug Administration.

Mike Pellini, M.D., is managing partner of Section 32, a venture capital fund investing in the frontiers of technology and health care; he previously served as the former chairman and CEO of Foundation Medicine and serves on the boards of directors of Adaptive Biotechnologies, Singular Genomics, Sema4 and the Personalized Medicine Coalition.

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