Thread by @nytimes

Rapid coronavirus tests that deliver results in minutes are becoming more widely available in the U.S.

But officials warn that the inconsistent public reporting of them is leading to the undercounting of cases and blurring the virus’s spread. nyti.ms/37ZXDrw

Antigen tests are faster than polymerase chain reaction (P.C.R.) tests, but are less able to detect low levels of the virus.

Antigen tests can help limit the spread of the virus, but as more of them become available, the undercounting could send the wrong message.

Washington, D.C., and seven states don’t publicly share case counts for those with antigen positive tests, including California, New Jersey and Texas.

Another six keep them separate from their total counts, and most of these report them less frequently. nyti.ms/3oPQVdF

Antigen tests are contributing a more visible share of reported cases.

For example, at least 26 of 254 Texas counties tally antigen positive cases on local health department websites.

The state health department, however, doesn’t yet report these.

Some state officials say their counts are incomplete because they don’t know where rapid testing is taking place.

Alabama has recently reported three spikes of older cases because some facilities had not reported their antigen test results to public health officials.

Antigen testing is expected to grow and may include portable kits that individuals can administer themselves.

Health officials say these home-based tests may be nearly impossible to track.

See more of our analysis of antigen testing. nyti.ms/3oPQVdF