A newly published study suggests that  Pfizer Inc. and BioNTech SE’s Covid-19 vaccine may be effective against a mutation found in two highly contagious variants of the coronavirus in the UK and South Africa.

The preliminary study, which was published by researchers at the University of Texas Medical Branch on Thursday focuses on whether the vaccine’s efficacy might be negated by the N501Y mutation in the virus’s spike protein that is common to both fast-spreading variants. 

The study examined the response to the mutant viruses in blood samples taken from 20 people who had gotten the companies’ mRNA vaccine as part of a previous clinical trial. The research didn’t study other mutations in the spike protein. Still, the antibodies in the vaccinated people’s blood did just as good a job at disarming the mutant virus as they did with the non-mutant version proving that the antibodies in the blood of people who had been vaccinated were able to neutralize the lab-created version of the mutant virus.

Though the study is in its preliminary stage and has not yet been reviewed by experts- a key step for medical research, Pfizer Chief Executive Officer Albert Bourla has expressed his pleasure with the recent development.

“We are encouraged by early in vitro study findings that show the sera from people who have received the Pfizer-BioNTech #COVID19 vaccine effectively neutralized a SARS-CoV-2 virus having one of the mutations also found in two highly transmissible strains,” his tweet read.

Executives at BioNTech had previously opined that they believed their vaccines would protect against the new strains. This recent study would be the first to back up the claims.