The Delta variant of the coronavirus does not appear to cause more severe disease in children than earlier forms of the virus, a UK study suggests. Another study found that in Covid-19 survivors, important components of the body’s immune response called memory B cells continue to evolve and get stronger for at least several months, producing highly potent antibodies that can neutralize new variants of the virus.

The effectiveness of the Pfizer Inc./BioNTech SE vaccine in preventing infection by the coronavirus dropped to 47 percent from 88 percent six months after the second dose, according to data published on Oct. 4 that U.S. health agencies considered when deciding on the need for booster shots.

Laboratory studies show that Merck & Co.’s experimental oral Covid-19 antiviral drug molnupiravir is likely to be effective against known variants of the coronavirus, including the dominant, highly transmissible Delta, the company said on Sept. 29.

A third shot of Sinopharm’s Covid-19 vaccine leads to a rebound in antibody levels that drop months after a second dose, a small-scale Chinese study showed.

Bharat Biotech’s intranasal Covid-19 vaccine candidate is expected to enter the Phase II portion of a Phase II/III study within the next few weeks. BBV154 marks the second vaccine against the novel coronavirus developed by the India-based company.

Vaccine developer Novavax Inc. said on Sept. 8 the company initiated an early-stage study to test a combination of the flu shot NanoFlu and the Covid-19 vaccine NVX-CoV2373.

The Bill & Melinda Gates Foundation will make a $35 million equity investment in privately owned Exscientia Ltd. to fund the development of antiviral drugs including for the coronavirus, the Oxford-based drug developer said on Sept. 8.

Pfizer Inc. started dosing in a mid-to-late-stage trial of the company’s oral antiviral therapy for Covid-19 in non-hospitalized, symptomatic adult patients.

A new coronavirus variant that was first detected in South Africa during May does not appear to be spreading, the World Health Organization said on Aug. 31, adding WHO was monitoring the variant as the virus evolves.

The number of coronavirus patients in U.S. hospitals breached 100,000, the highest level in eight months, according to the Department of Health and Human Services, as a resurgence of Covid-19 spurred by the highly contagious Delta variant strains the nation’s health care system.