Study shows booster shot after 6 to 12 months likely to provide best protection from COVID-19, Pfizer says

A study showed antibody titers five to 10 times higher than two doses.

Pfizer and BioNTech have released initial data from a study on booster shots for their COVID-19 vaccine, saying a third dose delivered about six months after the second shot has shown neutralization titers are five to 10 times higher than after two primary doses. The companies said they expect to publish "more definitive data" soon and submit the Food and Drug Administration "in the coming weeks." Pfizer said real-world evidence from Israel showed a decrease in efficacy about six months after people were fully vaccinated. "While protection against severe disease remained high across the full 6 months, the observed decline in efficacy against symptomatic disease over time and the continued emergence of variants are key factors driving our belief that a booster dose will likely be necessary to maintain highest levels of protection," Pfizer said in a statement.