The Pfizer/BioNTech vaccine can still target a key mutation that has emerged in two new variants of coronavirus, laboratory studies show.
However, this is only one of many mutations that are found in the new forms of the virus.
So while the study has been welcomed, it is not being seen as definitive scientific evidence about how the vaccine will perform.
New variants have been detected in the UK and South Africa.
Both forms of the virus are spreading more quickly and this has raised questions over what level of protection vaccines can offer against them.
The widely held view is that vaccines will still work, but researchers are on the hunt for proof.
The study by the University of Texas focuses on a mutation called N501Y, which as emerged in both new variants.
This is thought to be important because it is in the part of the virus that makes first contact with our body’s cells and changes could make it easier to get in and cause an infection.
The researchers created two forms of the virus – one with and one without the mutation – and then bathed those viruses in blood samples taken from 20 patients that had been vaccinated in clinical trials.
The results showed the immune systems of vaccinated patients were able to take out the new mutation.
However, the variant that emerged contain multiple mutations whose combined effects may help the virus evade the immune system.
“The mutation selected is only one of eight in the UK variant, and in fact was not expected to have significant impact alone,” Prof Ravi Gupta, from the University of Cambridge said.
Prof Stephen Evans, from the London School of Hygiene & Tropical Medicine, said: “Had the opposite result been found… that would have been bad and very concerning.
“So, yes this is good news, but it does not yet give us total confidence that the Pfizer (or other) vaccines will definitely give protection.”