Moderna Testing Booster To Combat New Variant

Cambridge-based Moderna will launch a clinical trial to study a potential COVID-19 booster shot after finding that its vaccine does not produce as significant a response to a new variant of the highly infectious virus first detected in South Africa, the company announced Monday.

Moderna said the vaccine is still protective against two new, more infectious variants — B.1.1.7, first identified in the United Kingdom, and B.1.351, first identified in South Africa — but that it produces six times fewer neutralizing antibodies in cases of the South African variant.

In response, Moderna plans to test a booster of its two-dose vaccine to increase immunization against new strains and start a clinical study of another booster aimed specifically at the B.1.351 strain.

"As we seek to defeat the COVID-19 virus, which has created a worldwide pandemic, we believe it is imperative to be proactive as the virus evolves. We are encouraged by these new data, which reinforce our confidence that the Moderna COVID-19 Vaccine should be protective against these newly detected variants," Moderna CEO Stephane Bancel said in a statement. "Out of an abundance of caution and leveraging the flexibility of our mRNA platform, we are advancing an emerging variant booster candidate against the variant first identified in the Republic of South Africa into the clinic to determine if it will be more effective to boost titers against this and potentially future variants."

Bancel did not offer a timeframe for the clinical trial.

State public health officials announced last week that they have detected the UK-originated variant in Massachusetts, but it is not clear if the Department of Public Health has found any cases of the second new strain.