White House chief medical adviser Anthony Fauci says the Moderna vaccine is likely to provide immunity against COVID-19 for at least six months.
Fauci told a news conference on Wednesday that there is a considerable amount of information about the duration of immunity.
Referring to a study of people who received two doses of the Moderna vaccine, Fauci said antibody activity remained high in all age groups for at least six months.
He also said that vaccines developed by other companies are expected to produce similar results.
He went on to say that further research is needed to determine the effect of a booster dose to extend the duration of immunity and whether the same effectiveness is maintained against variants.
The US pharmaceutical firm Pfizer and its German partner BioNTech said last month that their COVID-19 vaccine was 91.3 percent effective for up to six months after the second dose.