Who should get a third COVID-19 vaccine shot? About 2.7M immunocompromised Americans, CDC says

People with severely weakened immune systems should be able to receive a third dose of COVID-19 vaccine, the Centers for Disease Control and Prevention said.

"This official CDC recommendation – which follows FDA’s decision to amend the emergency use authorizations of the vaccines – is an important step in ensuring everyone, including those most vulnerable to COVID-19, can get as much protection as possible from COVID-19 vaccination," CDC Director Rochelle Walensky said in a statement Friday.

The Food and Drug Administration decided late Thursday to allow extra shots for people who are immunocompromised but left it up to the CDC to define exactly who should get the doses.

A CDC advisory committee spent four hours Friday considering evidence on the safety and effectiveness of extra shots for specific groups of people whose immune systems do not work well, either because of disease or medication.

The Advisory Committee on Immunization Practices voted unanimously to offer a third shot to a very narrow band of people: the 2.7% of Americans with the weakest immune systems, who were unlikely to get adequate protection from their initial shots.

Extra vaccines should be available in the next few days for the immunocompromised, who will be asked about their immune status before all vaccinations.

The severely immunocompromised are often left unprotected by the two-dose vaccine regimen from Moderna and Pfizer-BioNTech, studies have shown. Roughly 40% to 44% of people hospitalized with severe COVID-19 infections after vaccination are immunocompromised, the CDC said.

Immunocompromised people who contract COVID-19 are more likely to pass it on to people they live with.

Studies summarized Friday suggest an extra dose is safe for most people who are immunocompromised and increases their chance of getting protection against COVID-19.

According to the CDC, people who should be considered for a third dose are:

• Those in active cancer treatment; those who have received organ transplants and are taking immunosuppressive therapy.

• People who have received CAR-T cell or blood stem cell transplants.

• People who suffer from moderate or severe primary immunodeficiency (such as those with DiGeorge or Wiskott-Aldrich syndromes).

• People with advanced or untreated HIV infection.

• Those taking 20 milligrams or more or corticosteroids such as prednisone every day, or alkylating agents, antimetabolites, transplant-related immunosuppressive drugs, severely immunosuppressive cancer chemotherapeutic agents, TNF blockers and other biologic agents that are immunosuppressive or immunomodulatory.

As this is a wide and varied group, patients should discuss concerns and questions with their doctors, the committee said.

People will not be required to prove that they have one of these conditions to receive a third dose, but simply attest to their status.

CDC officials steered away from using the word "booster," emphasizing that the third shot would be part of a normal vaccination course for severely immunocompromised people.

The CDC and FDA have determined booster shots are not yet needed by the general population.

Although most people probably will need boosters eventually, initial shots do an excellent job of protecting people against serious disease and death, Walensky and others said.

At a White House briefing Thursday, Jeff Zients, who coordinates the president's COVID-19 task force, said the government has sufficient supply of vaccines to provide the public with boosters as they are needed.

The guidance on extra doses relates only to the two most commonly administered vaccines – from Moderna and Pfizer-BioNTech – and not to the Johnson & Johnson vaccine, which has not been studied among the immunocompromised.

A third dose of the Pfizer-BioNTech vaccine is available for the immunocompromised as young as 12, while Moderna is allowed only for adults because that vaccine has not been authorized for use in minors.

For a third dose, people should try to get the same vaccine they received the previous two times, but they could switch between Pfizer-BioNTech and Moderna if necessary, the CDC said.

Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said his agency is developing a solution for J&J recipients.

"We do understand the challenges here," Marks told the advisory committee. "We think at least there's a solution here for the very large majority of immunocompromised individuals, and we believe that we will probably have a solution for the remainder in the not-too-distant future."

The CDC does not recommend one vaccine over another for people who are immunocompromised.

Advocates for people with diabetes expressed concern that their population wasn't included for an extra dose. Having diabetes can increase someone's chances of a serious bout with COVID-19.

"We would encourage the agencies to ensure that we’re making available additional protections for those patients who we know suffer the worst outcomes from COVID-19," said Dr. Robert Gabbay, chief scientific and medical officer for the American Diabetes Association. "This includes Americans with diabetes, who would benefit tremendously from protections offered by additional COVID-19 doses.”

The list also leaves off people older than 80, who have weaker immune systems than younger people.

About 1% of Americans who have been vaccinated – more than 1 million total – have gotten themselves an extra shot.

Dr. Camille Kotton, a committee member and specialist in infectious diseases among the immunocompromised at Massachusetts General Hospital and Harvard Medical School, both in Boston, said she thinks this change will provide third dose access to people who might not otherwise know to get an additional dose.

Formally permitting third shots will allow the government to study the effects of extra doses.

"I hope it shows evidence that a booster shot is working for this group," said Philip Felgner, who directs the Vaccine Research and Development Center at the University of California, Irvine.

Even after a third dose, people who are severely immunocompromised need to take precautions to protect themselves against COVID-19, Walensky and others emphasized. Because it is not clear whether they will get adequate protection even after a third dose, people with weakened immune systems should continue to wear masks, maintain social distance and avoid crowds and poorly ventilated indoor spaces with strangers.

Contact Weintraub at kweintraub@usatoday.com

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This article originally appeared on USA TODAY: COVID vaccine booster recommended for 2.7M immunocompromised Americans