BioNTech/Pfizer boosters show 95.6% efficacy against Covid

Preliminary results follow a trial with 10,000 participants who had all completed a two-shot Pfizer regimen

A healthcare worker prepares a dose of the Pfizer-BioNTech Covid-19 vaccine. Photographer: Adam Glanzman/Bloomberg

A booster shot of the BioNTech/Pfizer vaccine is 95.6 per cent effective against Covid-19 compared with those receiving two shots and a placebo, the companies said on Thursday, citing preliminary results from the first randomised, controlled trial on boosters.

Ugur Sahin, the head of BioNTech, said the “important data” added to the body of evidence suggesting that a booster dose could help “protect a broad population of people from this virus and its variants”.

He added: “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.”

In a trial with 10,000 participants who had all completed a two-shot Pfizer regimen, half were randomised to receive a further, equal-strength dose of the shot, and half a placebo. Five cases of Covid-19 were registered in patients receiving the booster compared with 109 who were given a placebo. The trial took place during a period when the Delta viral variant was prevalent, and the median time between second and third doses was about 11 months.


The median age of participants was 53, with little more than half in the 16 to 55 age group. More than a fifth were older than 65, a category more at risk from severe Covid-19. Multiple subgroup analyses, the companies noted, showed that relative efficacy was “consistent” regardless of age, sex, race, ethnicity or other underlying conditions.

Safety profile

The safety profile of the vaccine was “generally consistent” with other data available, the companies added, adding they would share the information with US, EU and other regulatory agencies.

The discussion around boosters has been fractious, dividing the scientific community this year as companies including Pfizer and BioNTech said that protection afforded by their vaccines waned over time, especially against Covid-19 caused by the Delta variant.

The US Food and Drug Administration on Wednesday gave the green light to mix-and-match boosting, allowing any US citizen at high risk of contracting coronavirus to receive a further shot of any approved vaccine.

High-income countries, including Israel, the UK, and EU nations, have begun rolling out boosters to their populations to ensure they remain protected throughout winter, when transmission is aided by indoor mixing. Vaccination rates in lower-income nations consistently lag behind. - Copyright The Financial Times Limited 2021