Third Covid vaccine shot for people with weakened immune systems ‘very high priority,’ Fauci says

Federal health officials are working “as quickly as possible” to authorize a third Covid-19 vaccine shot for Americans with weakened immune systems, White House chief medical advisor Dr. Anthony Fauci said Thursday.

It is clear now that such people – including cancer and HIV patients or those who have had organ transplants – in general do not produce an adequate immune response after receiving two doses of a Covid vaccine, Fauci said.

“Immunocompromised individuals are vulnerable,” Fauci said during a White House briefing. “It is extremely important for us to move to get those individuals their boosters, and we are now working on that and we will make that be implemented as quickly as possible. … It is a very high priority.”

Immunosuppressed populations represent only about 2.7% of the U.S. adult population. Still, they make up about 44% of hospitalized Covid breakthrough cases — an infection in a fully vaccinated individual, according to recent data from a Centers for Disease Control and Prevention advisory group.

Studies suggest that a third vaccine shot might help patients whose immune systems don’t respond as well to a first or second dose.

Four small studies cited by the CDC last month showed that 16% to 80% of people with weakened immune systems didn’t have detectable antibodies to fight Covid after two shots. Among immunosuppressed patients who had no detectable antibody response, 33% to 50% developed an antibody response after receiving an additional dose, according to the CDC.

“It is clear now from observational data that was made that they do not, in general, do not make an adequate response that we feel would be adequately protected,” Fauci said Thursday.

Other countries, such as France, are already giving out third shots to people living with cancer or other immune impairments. Israel announced last month it would offer booster shots to people over age 60 as the shot’s effectiveness appears to wane in those individuals.

Some doctors have been pushing for the U.S. to allow immunosuppressed populations to get an extra dose, and many immunosuppressed Americans are already finding additional doses of the vaccines on their own, medical experts say.

Dr. Scott Gottlieb, who led the Food and Drug Administration from 2017 to 2019 during the Trump administration, told CNBC on Monday he believes booster shots will be given to older and immunocompromised people by September or October.

Disclosure: Scott Gottlieb is a CNBC contributor and is a member of the boards of Pfizer, genetic testing start-up Tempus, health-care tech company Aetion Inc. and biotech company Illumina. He also serves as co-chair of Norwegian Cruise Line Holdings’ and Royal Caribbean’s “Healthy Sail Panel.”