In two major COVID-19 developments today, the World Health Organization (WHO) updated its mask guidance, urging countries with widespread transmission to encourage mask use in situations where physical distancing isn't possible, and researchers from the United Kingdom stopped a large hydroxychloroquine trial after no benefit was found in hospitalized patients.

At a media briefing today, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, said the updated guidance has three main changes, plus new information on the construction of cloth face masks that was guided by research that it commissioned.

He said the new recommendations come with strong caveats that masks alone won't protect people from COVID-19 and that they should be used as part of comprehensive measures that also include physical distancing, hand hygiene, and other public health measures.

WHO officials today said the rationale for wearing a cloth face mask in certain settings is to provide a barrier that prevents the spread of droplets from people with asymptomatic or presymptomatic infections.

In another key development today, researchers from Oxford University involved in large randomized clinical trial of different drugs for treating COVID-19 (the Recovery trial) today announced that they have stopped the hydroxychloroquine arm of the study after a review of the data found no benefit in hospitalized patients.

The latest announcement comes at the end of a week that saw a flurry of new developments surrounding the controversial drug, including yesterday's retraction of a high-profile observational study due to questions about the validity of the data and the publication of a randomized controlled trial that found no benefits for preventing COVID-19 in people exposed to infected patients.

"We have concluded that there is no beneficial effect of hydroxychloroquine in patients hospitalised with COVID-19," they said.

"We have therefore decided to stop enrolling participants to the hydroxychloroquine arm of the RECOVERY Trial with immediate effect.

In the study, 1,542 patients were randomized to hydroxychloroquine and 3,132 were randomized to usual care.

The WHO-led Solidarity trial also had a large randomized controlled trial of treatments underway, including a hydroxychloroquine arm, which recently resumed after a pause to look for any potential safety signals.

Today CEPI, CSL, and the University of Queensland announced a partnership to speed the development of a COVID-19 vaccine candidate that uses the university's "molecular clamp" technology, expected to enter clinical trials in July.