Moderna’s COVID-19 vaccine may not respond as well against South African variant

Moderna (NSDQ:MRNA) announced today that it will start a Phase 1 study in the U.S. of an emerging variant vaccine booster candidate against a new COVID-19 variant out of South Africa. The company will also test an additional booster of its present vaccine.

The Cambridge, Mass.–based company said it has observed a sixfold reduction in neutralizing antibodies that its COVID-19 vaccine produces against the South African variant compared to earlier strains. But it still expects the two-dose regimen of its vaccine to be protective against emerging strains detected to date.

The in vitro neutralization studies, which involved sera from individuals vaccinated with Moderna’s vaccine, found no significant reduction in neutralizing antibodies related to the variant that has emerged out of the U.K.

In general, the question of how emerging variants impact vaccine efficacy is an unsettled, although it is possible they could lead to a “numerically meaningful drop,” according to one virologist.

“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 Stéphane Bancel said in a news release.

“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.”