The United States reported a 3 percent decline in new cases of Covid-19 for the week ended Feb. 28, a much smaller drop than in the previous six weeks, and health officials warned that progress against the global pandemic was stalling.

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.

Regeneron Pharmaceuticals said an independent panel found the company’s Covid-19 antibody cocktail to have “clear clinical efficacy” in reducing the rates of hospitalization and deaths in patients.

Public Health England (PHE) published real-world analyses of people in the U.K. who had received the first shot of the Pfizer-BioNTech Covid-19 vaccine, with the data – which were published in The Lancet – showing that there was a decrease of about 70 percent in infections among healthcare workers after the first shot.

Deaths from Covid-19 in the United States fell for a third straight week during the week ended Feb. 21, as cases and hospitalizations showed steep drops.

The United States on Feb. 22 crossed the staggering milestone of 500,000 Covid-19 deaths just over a year since the coronavirus pandemic claimed its first known victim in Santa Clara County, California.

The risk of illness from Covid-19 dropped 95.8% among people who received both shots of Pfizer’s vaccine, Israel’s Health Ministry said on Feb. 20.

The United States reported a 23% drop in new cases of Covid-19 and a 16% fall in the number of people hospitalized with the virus for the week ended Feb. 14, with both figures declining for a fifth week in a row.

The head of the U.S. Centers for Disease Control and Prevention said on Feb. 14 it is “absolutely” too soon to lift mask mandates, citing daily Covid-19 case numbers that despite recent declines remain more than double the levels seen the summer of 2020.

Israel’s largest healthcare provider reported a 94% drop in symptomatic Covid-19 infections among 600,000 people who received two doses of Pfizer’s vaccine in the country’s biggest study to date.