Moderna Inc (MRNA.O) said on Wednesday early human trial data shows that a third dose of either its current COVID-19 shot or an experimental new vaccine candidate increases immunity against variants of COVID-19 first found in Brazil and South Africa.

The booster shots, given to volunteers previously inoculated with Moderna’s two-dose vaccine regimen, also boosted antibodies against the original version of COVID-19, Moderna said.

The early data comes from a 40-person trial testing both Moderna’s existing shot and a version developed to protect against the South African variant of COVID-19 called mRNA-1273.351. Moderna is also studying a shot that combines both the new and existing vaccine.