WASHINGTON — Dr. Anthony Fauci says there’s reason to be concerned about the impact of some coronavirus mutations on vaccines, but scientists have plenty of options for adjustments to maintain the effectiveness of vaccines and treatments.

The government’s top infectious disease expert says there’s particular concern about the so-called South African variant, because lab tests have shown that it can diminish the protective power of the vaccines approved to date.

However, Fauci stressed the level of protection provided was still well within what he called the “cushion” of vaccine effectiveness.

Fauci says one vaccine that’s still in testing is being measured for effectiveness against the South African variant and another strain that has emerged in Brazil. He called that a promising development.