Research finds the P.1. coronavirus variant infected patients in Brazil who had recovered from Covid-19, FDA grants an emergency use authorization for an at-home Covid-19 antigen test, and more.

• The P.1. coronavirus variant, first discovered in Brazil, infected a number of people who had already recovered from Covid-19 in the city of Manaus, according to three studies on the variant. The studies, which have not yet been published, also suggest the variant likely first appeared in Brazil in November and fueled a spike in Covid-19 cases, in part because it's more contagious than the original version of the novel coronavirus. Further, the findings from lab experiments suggest the variant may weaken the protection provided by a Covid-19 vaccine developed in China that's being used in Brazil. However, Nuno Faria, a virologist at Imperial College London who helped lead some of the research, cautioned that lab findings don't always apply to the real world. "The findings apply to Manaus, but I don't know if they apply to other places," he said. According to CDC, the P.1. variant has been discovered in 24 other countries, with six cases found in the United States (Zimmer, New York Times, 3/3).

• More than a dozen health insurers have launched the Vaccine Community Connectors program, which aims to help two million seniors from underserved populations learn more about Covid-19 vaccines, schedule appointments, and arrange for transportation. Under the program, providers will contact Americans over the age of 65 in areas of "high social vulnerability" who have not yet been vaccinated to discuss the efficacy, safety, and value of vaccines, Andy Slavitt, a senior adviser to the White House's Covid-19 response team, said (Lovelace, CNBC, 3/3; Treisman, NPR, 3/3; Parti, Wall Street Journal, 3/3).

• The Covid-19 vaccine developed by Johnson & Johnson (J&J) can be used as a substitute for a second shot of the Covid-19 vaccines developed by Pfizer/BioNTech and Moderna "[i]n exceptional situations," such as "due to a contraindication" or an allergic reaction to the first dose, Jessica MacNeil, an epidemiologist at CDC's National Center for Immunization and Respiratory Diseases, said Monday. MacNeil noted, however, that the three vaccines "are not interchangeable" and the safety and efficacy of taking one shot of Pfizer/BioNTech's or Moderna's vaccine and one shot of J&J's vaccine has not yet been tested. Separately, CDC on Tuesday said that, as states expand access to Covid-19 vaccines, they should prioritize people with disabilities or cognitive decline and their caretakers, as well as "those with limited access to technology" (Feuer, CNBC, 3/1; Sun, Washington Post, 3/2).

• FDA has issued an emergency use authorization for Quidel's at-home, prescription Covid-19 antigen test. The test, called the QuickVue At-Home Covid-19 Test, does not require test samples to be sent to a lab and can be self-administered by patients ages 14 and older with a nose swab, FDA said. The test can be used on children as young as eight if an adult collects the sample, FDA added (Anderson, Becker's Hospital Review, 3/2).

• The World Health Organization's Guideline Development Group in The BMJ Tuesday wrote that the drug hydroxychloroquine should not be used to prevent Covid-19 and does not have a meaningful effect on Covid-19 patients. The panel of experts wrote that their "strong recommendation" is based on evidence from six different randomized, controlled trials that involved over 6,000 participants with and without Covid-19. The experts wrote that they have "judged that almost all people would not consider this drug worthwhile" (Kelland, Reuters, 3/1).