Novavax Inc.’s experimental Covid-19 vaccine showed immune response and protection against the highly contagious coronavirus variant originally identified in South Africa in a clinical trial.

France’s Sanofi and Britain’s GlaxoSmithKline launched a late-stage human trial for a recombinant Covid-19 vaccine candidate on May 27 which they hope to get approved by the end of 2021.

Moderna Inc. said on May 5 early human trial data shows that a third dose of either the company’s current Covid-19 shot or an experimental new vaccine candidate increases immunity against variants of Covid-19 first found in Brazil and South Africa.

An experimental monoclonal antibody treatment for Covid-19 being developed by Eli Lilly and Co. and AbCellera Biologics Inc. can “potently” neutralize numerous coronavirus variants, including those first identified in the UK, Brazil, South Africa, California and New York, scientists found in test tube experiments. According to another study, some Covid-19 survivors infected early in the pandemic still have detectable antibodies against the virus a year later.

Pfizer Inc. and BioNTech said on April 1 their Covid-19 vaccine is around 91 percent effective at preventing the disease, citing updated trial data that included participants inoculated for up to six months.

Pfizer Inc. and BioNTech SE said on March 10 that real-world data from Israel suggests their Covid-19 vaccine is 94 percent effective in preventing asymptomatic infections, meaning it could significantly reduce transmission.

The Covid-19 vaccine from Pfizer Inc. and BioNTech SE was able to neutralize a new variant of the coronavirus spreading rapidly in Brazil, according to a laboratory study published in the New England Journal of Medicine on March 8.

Preliminary data from a study conducted at the University of Oxford indicates that the Covid-19 vaccine developed by AstraZeneca is effective against the Brazilian variant P1, a source with knowledge of the study told Reuters on March 5.

Mayor Bill de Blasio’s chief medical adviser on Feb. 25 downplayed the results of two studies suggesting that a new coronavirus variant found in New York City in November will be more resistant to vaccines now being administered.

Many health experts believe that the Covid-19 vaccine candidate NVX-CoV237 from Novavax offers potential advantages over competitors including Pfizer-BioNTech, Moderna, Johnson & Johnson, and AstraZeneca-Oxford.