Data from Johns Hopkins University demonstrate that daily Covid-19 infections increased 316 percent from Labor Day 2020, or about four times more.

The Covid-19 vaccines developed by Pfizer Inc. with BioNTech SE and Moderna Inc. are highly effective and reduced the risk of infection by 90 percent by two weeks after the second shot among healthcare personnel and first responders, according to a U.S. study released on March 29.

Los Angeles health officials told first responders to stop bringing adult patients who cannot be resuscitated to hospitals, citing a shortage of beds and staff as the latest Covid-19 surge threatened to overwhelm healthcare systems in America’s second-largest city.

Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), noted that it would take time – possibly months – before people 18 years of age and younger could get a Covid-19 vaccine because clinical trials were either underway or had not yet begun.

A roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for Covid-19 shows that New York City first responders have high Covid-19 rates.