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.