CDC director Robert Redfield briefs reporters on April 8. Photo: Mandel Ngan/AFP via Getty Images

Coronavirus antibody tests are still relatively unreliable, and it's unclear if people who get the virus are immune to getting it again, the Centers for Disease Control and Prevention cautioned on Tuesday.

What they're saying: The agency explicitly warned against using antibody tests to determine whether someone should return to work or to group people within schools or prisons.

  • Although some evidence suggests that previously having the coronavirus could create "short-term immunity," it is still ultimately unknown whether having COVID-19 antibodies offers protection from the virus, the agency said.
  • Social distancing and face masks are still essential and should not be avoided based on whether you have coronavirus antibodies. More data would be needed for those changes, the agency says.

Between the lines, via Axios' Caitlin Owens: The CDC's updated guidelines point out that even effective antibody tests are likely to have high false positive rates, since not many people have tested positive for the coronavirus.

The big picture: The CDC's caution comes after it confirmed last week that it had been combining the results of diagnostic and antibody coronavirus tests. This distorts data on how widespread the virus is, which is one of the primary uses of antibody tests.

  • It also follows a warning from the American Medical Association that antibody tests that identify those who have previously contracted the coronavirus should not be used to determine immunity.

Go deeper: FDA blocks sale of 29 coronavirus antibody tests in the U.S.

Go deeper

Updated 24 hours ago - Health

The states where face coverings are mandatory

Data: Compiled by Axios; Map: Danielle Alberti/Axios

Mississippi Gov. Tate Reeves issued a statewide mask mandate on Tuesday for those in public, as well as for teachers and students going back to school.

The big picture: 34 states, in addition to the District of Columbia, have issued some form of mask mandate as infections surge across the country.

19 hours ago - Health

First bipartisan multistate coronavirus testing drive to tackle shortages

A Whittier Street Health Center nurse performs a COVID-19 test in Roxbury, Massachusetts, on Monday. Photo: Matt Stone/MediaNews Group/Boston Herald

A bipartisan group of governors has joined the Rockefeller Foundation to deliver 3 million rapid coronavirus antigen tests to slow the spread of COVID-19 and help states safely reopen, the nonprofit announced Tuesday.

Why it matters: With no national plan, the initiative with Maryland Gov. Larry Hogan (R), Louisiana Gov. John Bel Edwards (D), Massachusetts Gov. Charlie Baker (R), Michigan Gov. Gretchen Whitmer (D), Ohio Gov. Mike DeWine (R), and Virginia Gov. Ralph Northam (D) would be the first coordinated testing strategy in the U.S.

Updated 22 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 3:30 p.m. ET: 18,614,542 — Total deaths: 702,330 — Total recoveries — 11,181,018Map.
  2. U.S.: Total confirmed cases as of 3:30 p.m. ET: 4,793,950 — Total deaths: 157,416 — Total recoveries: 1,528,979 — Total tests: 58,239,438Map.
  3. 2020: Joe Biden will no longer travel to Milwaukee for Democratic convention.
  4. Public health: Florida surpasses 500,000 confirmed casesModerna skirts disclosures of vaccine costs.
  5. Sports: The return of high school sports hangs in the balance — UConn becomes first FBS team to cancel football season.
  6. Education: Chicago Public Schools to begin school year fully remote.