SAN FRANCISCO (KRON) — The FDA has approved a COVID-19 booster shot for people who have a weakened immune system – this includes cancer patients and people who have had organ transplants.

U.S. regulators say this vulnerable group has a lower chance to fight COVID-19.

After looking at data, the FDA gave Pfizer and Moderna the greenlight to administer the additional dose.

People should get it at least 28 days after receiving their most recent COVID-19 dose. This booster shot approval doesn’t apply to people who have a healthy immune system.

The decision comes after COVID cases surge across the country. California has an average of 141 new coronavirus cases each day. Plus, more than 700 people are admitted to the hospital daily because of complications due to the virus.

Moderna responded on Friday morning to the FDA’s decision.

The company’s chief executive officer says they will continue to research COVID-19.

Moderna officials said there was a recent study done of 120 people who underwent an organ transplant procedure.

The study showed a third dose improved their immune system.

The FDA did not mention anything about the Johnson and Johnson vaccine in their announcement.

The CDC has yet to comment on the authorization, but the CDC’s committee on immunization practices is planning to meet Friday.