Pfizer Inc. said that U.S. regulators should approve a booster dose of the COVID-19 vaccine it developed with Germany's BioNTech SA six months after the second dose due to waning effectiveness of the shot over time, according to documents the drugmaker submitted to the U.S. Food and Drug Administration.
The FDA released the documents on Wednesday for consideration by a committee of outside experts who will meet Friday to vote on recommending if U.S regulators should approve the extra shots.
Pfizer said data from its own clinical trials showed that the vaccine efficacy had waned by around 6 percent every two months after the second dose. It also said the incidence of breakthrough cases in that trial was higher among people who received their shots earlier.
The drugmaker also pointed to real world data from Israel and the United States showing declining effectiveness of the vaccine.
It said that a roughly 300-participant clinical trial showed that the third dose generated a better immune response than the second dose. It also pointed to data from the booster program recently started in Israel to show that a third dose restores high levels of protection from the virus.
President Joe Biden has pushed for the additional shots in the face of surging hospitalizations and deaths caused by the highly contagious Delta variant, and set a Sept. 20 target to begin administering 100 million booster shots.
But it is not clear to many scientists whether the additional shots are necessary broadly. Earlier this week, two top FDA vaccine scientists were among the authors of an article saying that they do not believe the data currently supports giving the shots. One of those scientists -- Marion Gruber, director of the FDA's Office of Vaccines Research and Review -- will be speaking at the meeting on Friday.
Some U.S. officials are hoping boosters might prevent mild cases and reduce transmission of the virus as well as reducing serious infections, which could hasten America's recovery.
Some countries have already begun COVID-19 booster campaigns. The United States authorized extra shots for people with vulnerable immune systems last month.
The FDA has not yet published the briefing with its view on the issue.
"We are working to post all of the documents for this important meeting, many of which contain complex data, as quickly as possible but are posting items throughout the day as they are finalized and available," an FDA spokesperson said.