Wednesday's posting by the Food and Drug Administration included much of what its advisory panel will be considering. The agency took a neutral tone regarding boosters, which is unusual considering that President Joe Biden and his top advisors had announced that they would be starting a booster campaign next week.
Pfizer's argument is that while severe diseases are still protected in the United States, immunity to milder infections decreases around six to eight month after the second dose. At that point, the company gave 306 more doses to patients and found levels of virus-fighting antibody three times higher than those who received the first shots.
Pfizer stated that the antibodies are strong enough to fight the extra-contagious Delta variant spreading around the country.
Pfizer provided data from Israel to support its case. The FDA began offering boosters in the summer.
The study involved 1,000,000 people aged 60 or older. It found that those who received the additional shot were less likely to contract the disease soon afterward. Pfizer stated that this translates into "roughly 95% effectiveness" as delta spreads, which is comparable to protection received shortly after the vaccine was introduced earlier in the year.
Data from Israel, published Wednesday in The New England Journal of Medicine, does not indicate how long the boosted protection will last.
However, FDA reviewers suggested that they would focus on research on vaccine effectiveness among Americans.
The data indicate that Pfizer and other U.S.-authorized COVID-19 vaccinations "still provide protection against severe COVID-19 diseases and death in the United States," according to the agency.
The FDA isn't bound to follow the advice from its independent advisory panel. The FDA could confuse the public if it ignores its independent advisory panel. Two top FDA vaccine regulators joined an international group of scientists in rejecting boosters for otherwise healthy people earlier this week. They cited the strong ongoing protection against severe diseases.