The companies have received emergency use authorization from the US Food and Drug Administration and Pfizer says it will now seek full approval.
Pfizer's Chief Executive Officer Albert Bourla said the updated result, which includes data on more than 12,000 people fully inoculated for at least six months, positions the drugmakers to submit for full USA regulatory approval. And it appeared to be fully effective against the worrying B.1.351 variant of the virus, which is the dominant strain circulating in South Africa and which researchers feared had evolved to evade the protection of vaccines, the companies said. "These data also provide the first clinical results that a vaccine can effectively protect against now circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population". The FDA has previously said that it will expedite the authorization process for updated COVID-19 vaccines that target variants, according to CNBC. Six of the nine were confirmed to be caused by B.1.351.
"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 offer the first data in humans about how so-called mRNA vaccines such as Pfizer's will perform against the South African variant.
The updated trial data would not prompt the company to change that development strategy, a BioNTech spokeswoman said.
The variant vaccine is similar to the current Moderna COVID-19 vaccine that has received FDA authorization in the US, but it differs slightly in that it incorporates key mutations from the B.1.351 variant.
"This approach could maximise the reach of a limited vaccine supply, allowing potentially millions more people to be vaccinated in the U.S. alone", she added.
'The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine's overall effectiveness'.
The vaccine was 100 per cent effective in preventing severe disease as defined by the US Centers for Disease Control and Prevention and 95.3 per cent effective in preventing severe disease as defined by the US Food and Drug Administration.
In the first in-human evidence of how the vaccine protects against variants, research published by Pfizer/BioNTech on Thursday showed the vaccine is 100% effective in preventing Covid-19 cases in South Africa - where the South African variant is now common.
'The information coming from Pfizer-BioNTech is good news with evidence that those enrolled in the clinical trials previous year are still protected.