People with asymptomatic or mild illness generally test negative after nine days. A polymerase chain reaction (PCR) test can be positive for up to 90 days after infection.

Free at-home Covid tests can be ordered starting Monday. Here’s what you should know about when to test and what the results mean as new variants circulate.

Most people who contract COVID-19 likely won’t experience symptoms for more than two weeks at most, but could test positive months following infection.

The PCR test, which involves replicating a segment of COVID-19 DNA, is distinct from human cloning. In addition, the paper cited as evidence predates the pandemic and is unrelated to human cloning.

If a rapid test produces a negative result but you have a cough, fever or other symptoms, the CDC recommends you also do a PCR test.

The FDA granted marketing authorization to a Visby Medical at-home PCR test for three common sexually transmitted infections. The Visby test yields results in about 30 minutes.

Polymerase chain reaction (PCR) test kits for COVID-19 use what’s known as gene cloning – not reproductive cloning – to detect the presence or absence of the SARS-CoV-2 virus, but social ...