In a statement, which cites preliminary results, Moderna maintains that its vaccine "maintains neutralising activity" for the SARS-CoV-2 variants originating in the UK and South Africa, and already detected in Portugal.
According to the biotech company, "the two-dose regimen" of the vaccine is expected to "protect against the emerging strains detected to date".
The statement said that for the British variant, "no significant impact on neutralising [antibody levels] titres has been found.
For the South African variant, "a six-fold reduction in neutralising titres has been observed," but such levels "remain above" those that are "expected to provide protection.
Moderna advises, however, that it is "as a precaution" developing a "booster variant" of its vaccine against the South African strain and will test "an additional dose of booster" of the vaccine to assess "the ability to further increase neutralising titres against emerging strains".
The results, which still require peer review for scientific publication, were obtained from an 'in vitro' study which examined, from human serum and monkeys, the vaccine's ability to induce the formation of powerful neutralising antibodies against the two variants.
The work was done by the biotechnology company in collaboration with the National Institute of Allergy and Infectious Disease Vaccine Research Centre in the United States.
"We are excited about these new data, which strengthen our confidence that the modern Covid-19 vaccine should bring protection against these new detected variants," said Moderna boss Stéphane Bancel, quoted in the statement.