A booster shot of the Pfizer-BioNTech vaccine was found to be 95.6% effective against COVID-19, the companies announced on Thursday.

The result is from a large Phase 3 trial “with more than 10,000 participants 16 years of age and older” that was conducted “during a period when Delta was the prevalent strain.”

“In the trial, a booster dose administered to individuals who previously received the Pfizer-BioNTech primary two-dose series restored vaccine protection against COVID-19 to the high levels achieved after the second dose, showing a relative vaccine efficacy of 95.6% when compared to those who did not receive a booster,” read a joint statement.

Some 55.5% of the participants were between 16 and 55 years, while 23.3% were 65 years and older.

They randomly received a 30-microgram vaccine dose or a placebo, with the median time between a person’s second dose and the booster or placebo being approximately 11 months.

“Symptomatic COVID-19 occurrence was measured from at least 7 days after booster or placebo, with a median follow-up of 2.5 months. During the study period, there were 5 cases of COVID-19 in the boosted group, and 109 cases in the non-boosted group,” the statement said.

The efficacy was consistent irrespective of age, sex, race, ethnicity, or comorbid conditions, it added.

Ugur Sahin, cofounder of BioNTech, said the data supports “evidence suggesting that a booster dose of our vaccine can help protect a broad population of people from this virus and its variants.”

“Based on these findings we believe that, in addition to broad global access to vaccines for everyone, booster vaccinations could play an important role in sustaining pandemic containment and a return to normalcy,” he said.

The companies now plan to submit detailed results from the trial for peer-reviewed publication and share data with the US Food and Drug Administration, European Medicines Agency, and other regulatory agencies around the world as soon as possible, the statement added./agencies