Federal regulators have approved a longer shelf life for the Johnson & Johnson COVID-19 vaccine.

Federal regulators have approved a longer shelf life for the Johnson & Johnson COVID-19 vaccine.

WASHINGTON — Federal health regulators on Wednesday again extended the expiration dates on Johnson & Johnson's COVID-19 vaccine, providing health workers with six more weeks to use millions of doses of the shot.

Vaccine expiration dates are based on information from drugmakers on how long the shots stay at the right strength.

The FDA has been reviewing expiration dates on all three U.S.-authorized vaccines as companies have continued to test batches in the months since the shots first rolled out.