Nearly 31 million Americans have already received a dose beyond their original vaccination, including those with weakened immune systems, such as cancer patients and organ transplant recipients who need an extra dose to be fully vaccinated.
While all three vaccines used in the U.S. continue to offer strong protection against severe COVID-19 illness and death, the shots’ effectiveness against milder infection can wane over time.
Pfizer has submitted early results of a booster study in 10,000 people to make its case that it’s time to further expand the booster campaign. The study found that a booster could restore protection against symptomatic infection to about 95%, even as the extra-contagious delta variant was surging. Side effects were similar to those seen with the company’s first two shots.
Members of the panel, the Advisory Committee on Immunization Practices, have debated in prior meetings whether there is sufficient evidence that boosters are currently needed for all adults.