Pfizer and BioNTech, makers of a Covid-19 vaccine, said on Thursday that their product is effective against coronavirus variants that have emerged in Britain and South Africa.
In a statement, the two companies said the "small differences" detected in tests comparing the original virus and the recent versions "are unlikely to lead to a significant reduction in the effectiveness of the vaccine".
While the findings indicated no need for a new vaccine to tackle the new strains, Pfizer and BioNTech said they would respond if there was evidence that the variants could defeat their current vaccine.
They would continue to monitor their vaccine's "real-world effectiveness", including against new strains, they said.
"Pfizer and BioNTech believe that the flexibility of BioNTech's proprietary mRNA vaccine platform is well suited to develop new vaccine variants if required," they said.
Daily global deaths from Covid-19 topped 18,000 for the first time Wednesday, with vaccines seen as the only real chance of returning to some form of normality.