Hot Off the Press: “Considerations in Boosting COVID Vaccine Immune Responses”

September 13, 2021

This morning, The Lancet published a viewpoint article regarding COVID-19 boosters; co-authors include Dr. Krause and Dr. Gruber from the Office of Vaccines Research and Review, Food and Drug Administration (FDA).

The authors begin by addressing boosters for immunocompromised persons, stating it is still unknown whether this population would receive worthwhile benefit from an additional dose of the same vaccine, or if implementing a mix-and-match method may complement the primary immune response more effectively.

Randomized trials and observational studies have not yet shown a need for boosting the general population. “A consistent finding is that vaccine efficacy is substantially greater against severe disease than against any infection… although the efficacy of most vaccines against symptomatic disease is somewhat less for the delta variant than for the alpha variant, there is still high vaccine efficacy against both symptomatic and severe disease due to the delta variant.” Even if antibodies appear to decrease, their reduction does not necessarily predict reductions in vaccine efficacy against mild and severe disease. Protection against severe disease utilizes antibody responses as well as memory responses and cell-mediated immunity.

Developing variant-based boosters in the same way as the influenza vaccine will increase the likelihood of the vaccine remaining effective even if there is further strain mutation. As of now, the current vaccines elicit a humoral response against circulating variants.