In a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines, Covid-19 antibodies last at least three months and so do symptoms for many.

The widely used BCG tuberculosis vaccine will be tested on frontline care workers in Britain for its effectiveness against Covid-19, researchers running the UK arm of a global trial said.

Treating critically ill Covid-19 patients with corticosteroid drugs reduces the risk of death by 20 percent, an analysis of seven international trials found, prompting the World Health Organization to update its advice on treatment.

Global coronavirus cases pushed past 20 million, according to a Reuters tally, with the United States, Brazil and India accounting for more than half of all known infections.

U.S. deaths from the novel coronavirus surpassed 150,000, a number higher than in any other country and nearly a quarter of the world’s total, according to a Reuters tally.

Recently published scientific studies include research into whether Covid-19 immunity might not be possible.

The novel coronavirus has killed more than 100,000 people in the United States, according to a Reuters tally, even as the slowdown in deaths encouraged businesses to reopen and Americans to emerge from more than two months of lockdowns.

The number of new cases of COVID-19 is easing in some parts of Europe, including Italy and Spain, but outbreaks are still growing in Britain and Turkey, the World Health Organization (WHO) said.

Regeneron and Sanofi dosed the first patient outside of the United States with the rheumatoid arthritis drug Kevzara as part of a second global clinical trial assessing the medication as a treatment for COVID-19, the disease caused by the novel coronavirus pandemic.

Sanofi and Regeneron Pharmaceuticals expanded a clinical trial of the companies’ rheumatoid arthritis drug Kevzara as a coronavirus treatment to patients outside the United States.