US health officials warn of false positive results for Covid-19 test

US health officials are warning health professionals about the risk of false positive results with a widely used laboratory test for COVID-19 and flu.

The Food and Drug Administration issued the alert to Friday for health facilities using Roche's cobas test for coronavirus and seasonal flu. The agency warned that problems with the test's processing tubes could result in false diagnosis in people who are not actually infected.

Roche's testing system is widely used to screen large batches of patient samples in hospitals and laboratories.

The FDA recommends health workers test samples multiple times to help assure accuracy. If the test delivers conflicting results it may indicate a problem and use should be discontinued, the agency says.