Pfizer Inc and BioNTech said on Thursday their vaccine is around 91% effective in preventing COVID-19, citing updated trial data that included participants inoculated for up to six months.
The shot also showed new signs of preventing disease in a small subset of study volunteers in South Africa, where a concerning new variant called B.
1.351 is circulating. Although lower than the major 95% efficacy outcome reported in November from its 44,000- person clinical trial, overall efficacy of 91.3% shows the vaccine to be a powerful tool against an evolving virus.
The virus has now developed more transmissible forms and ones that have been shown to evade antibody protection in clinical studies and in real-world lab tests.
These results confirm our view that we have some really potent vaccines, said Danny Altmann, a professor of immunology at the Imperial College London in Britain who was not involved in the Pfizer trial.
Pfizer's Chief Executive Albert Bourla said the updated result, which includes data on more than 12,000 people fully inoculated for at least six months, will position the drugmakers to submit for full U.S. regulatory approval.
The vaccine is currently approved by the U.S. Food and Drug Administration on an emergency basis.
The research results provide the first clinical results that a vaccine can effectively end circulating variants, a critical factor to reach herd immunity and avoid this pandemic for the global population, said Ugur Sahin, chief executive of BioNTech in a statement. Experts fear existing variants of COVID 19 from Brazil and South Africa may be resistant to new vaccines and treatments.
According to federal data, more than 300 cases of the South African variant have been detected in more than 25 U.S. states and jurisdictions.
Lab tests have indicated that the Pfizer BioNTech vaccine was earlier developed but still offered a robust defense against the B.1.351 variant which appeared in South Africa. The data released on Thursday offered the first look at how the vaccine could work in humans against the South African variant. Among a group of 800 study volunteers in South Africa, where the variant is widespread, there were nine cases of COVID-19- 19, all of which occurred among participants who got the placebo.
From these nine cases, six were among individuals infected with the South African variant.
The Pfizer data are a big deal, said Shane Crotty, a virologist at the La Jolla Institute for Immunology in San Diego, noting that the results provide the first data in humans about how so-called mRNA vaccines such as Pfizer's will perform against the South African variant.
Six infections versus zero are something, he noted in an email, but the sample size is still not enough to make conclusions about protection.
Although the B. 1.1.
7 variant which originated in South Africa has rapidly spread across Europe and is gaining a foothold in the U.S., the B.
1.351 variant and similar variants are more worrying because they have shown to reduce the efficacy of three different COVID-19 vaccines in clinical trials in Britain.
BioNTech reiterated this week that there would likely be a future need for booster shots that specifically address new variants and that the group was preparing to upgrade its vaccine when needed.
A spokesperson said on Thursday that its strategy remains in place.
The vaccine was 95.3% effective in preventing serious disease as defined by the U.S. Food and Drug Administration. There were also no serious safety concerns observed in trial participants up to six months after the second dose, the companies said. The trial included more than 900 confirmed COVID- 19 cases, most of which were among participants who received a placebo. The results follow separate data that show the vaccine is effective in 12 to 15-year-olds, which would pave the way for drugmakers to seek U.S. and European approvals for this group.