AstraZeneca Plc’s and Pfizer Inc.’s Covid-19 vaccines may help protect patients from the coronavirus variant that emerged in Brazil, scientists said in a study that may alleviate some concerns about their role in slowing the pandemic.

Laboratory experiments indicate that the shots are about as effective against the Brazil variant as another that surfaced in the UK, which has already been shown to be halted by existing vaccines, according to data released Thursday by the University of Oxford. Both inoculations fared a lot less well against another mutant that surfaced in South Africa.

Viruses constantly mutate, and researchers are studying new versions to see what impact they’ll have on global efforts to immunize populations and restore economies, schooling and societies. Companies are already developing booster shots that specifically target the mutant coronaviruses.

The UK and Brazil variants rendered the vaccines about three times less effective than against earlier strains, the scientists found. Against the South Africa variant, the researchers found a nine-fold reduction in the level of neutralization by the Astra vaccine and a 7.6-fold reduction for the Pfizer shot.

The estimates are based on levels of antibodies, immune proteins that can stop viruses from entering cells, that were found in the blood of people who were vaccinated or recovered from Covid. The study was not reviewed by other experts.

Bavarian Nordic's 2021 will be full of development 

Jefferies valuates Bavarian Nordic's Covid-19 project 

Bioporto CEO holds Covid-19 test at arm's length: "Could be everything or nothing"