They’re cancer patients. Transplant recipients. People with lupus, rheumatoid arthritis, HIV/AIDS, sickle cell disease, kidney failure and Crohn’s disease. Plus millions of others who have conditions or take medications that weaken their immune systems.

That makes them – millions of teens and adults – what doctors call immunocompromised.

And that puts them at much higher risk of serious illness if they get COVID-19, which is why many states prioritized them for vaccination early this year.

Now, most of them are now eligible for even more protection.

The FDA and CDC have just approved and recommended an additional dose of mRNA COVID-19 vaccines as part of a primary series for moderately and severely immunocompromised people.

The additional dose should be the same mRNA COVID-19 vaccine as the first two shots the person received before, and should be administered at least 28 days after completion of the initial primary series of two shots. Specifically, those who have had two doses of the Pfizer vaccine can get a third dose of that vaccine, and those who have had two doses of the Moderna vaccine can get a third dose of that vaccine.

This is not considered a “booster shot,” but rather an additional dose to the recommended use of COVID-19 vaccines in these individuals. It’s being recommended because they have likely not produced an adequate immune response after getting the first two doses of COVID-19 vaccine.

Currently there is not data to support giving a dose of mRNA COVID-19 vaccine to immunocompromised people whose previously received the one-dose Johnson & Johnson/Janssen vaccine. A recommendation for immunocompromised people who got that vaccine is still being developed.

Immunocompromised people are more likely to get severely ill from COVID-19, are at higher risk for prolonged viral infection and shedding of the virus, are more likely to transmit the infection to people they live with, and show a lower immune response to vaccination compared to non-immunocompromised people, says Pamela Rockwell, DO, a Michigan Medicine family physician and associate professor at the University of Michigan Medical School.

She represents the American Academy of Family Physicians on the CDC advisory panel that just approved the new recommendation.

“As COVID-19 surges across the country, vaccinated people who are immunocompromised and have completed a two-dose series of either the Pfizer or Moderna COVID-19 vaccine series should obtain a third dose of the same mRNA vaccine that they have already received, at least 28 days from their second vaccine dose. This includes children and adolescents 12 and older who are immunocompromised,” said Rockwell.

“If you aren’t sure if you or your child falls into this group, talk with a trusted health care provider,” she added. “And if you fall into the third-dose group, but you haven’t gotten vaccinated at all yet, or haven’t finished your two-dose series, now’s the time to do it.”

Other steps immunocompromised people should take

Vaccination is not all people in this group should do, she adds.

“It’s important for immunocompromised people to wear masks in public, maintain social distancing of at least 6 feet from people they do not live with, avoid crowds and poorly ventilated indoor spaces until advised otherwise by their healthcare provider, and to encourage everyone over the age of 12 who interacts with them closely to get vaccinated if they aren’t already,” she said.

“They may not realize how much they are putting you at risk, or that your immunocompromised state puts you at high risk of severe COVID-19,” she added. “Ask them to help protect you.”

Rockwell also encourages people who get a third dose of COVID-19 vaccine to sign up for the CDC’s V-safe system, which will text them occasionally to ask them to report any reactions to the vaccine. This will help collect data that will guide the vaccination process and look for any rare effects.

Surging spread poses risk to immunocompromised people

The new approval couldn’t have come at a better time, given the fact that nearly the entire country is now experiencing high levels of spread of the coronavirus because of the highly contagious Delta variant.

It’s also a reminder of the fact that immunocompromised people remain vulnerable to severe cases of COVID-19 even after they’ve gotten vaccinated.

And some of them may not have gotten vaccinated yet, because their doctors are following recommendations that advise them to wait a certain amount of time after they finish a cancer therapy or get a transplant.

While the overwhelming majority of people hospitalized for COVID-19 right now are unvaccinated adults and children, many of the rest of those in hospitals for COVID-19 care have a condition or take a medication that affects their immune system.

Advanced age can also affect immune response, but the new recommendation is not age-based. And a recent study by a U-M team found that nearly 3% of insured United States adults under the age of 65 take medications that weaken their immune systems. The findings, made using data from over 3 million patients, focused on people taking chemotherapy medications and steroids such as prednisone.

Who’s eligible for a third dose?

Here’s a partial list of the conditions and treatments that could qualify someone for a third dose of COVID-19 vaccine.

If you have one of these conditions or are on one of these treatments, or have another condition or take another medication that affects your immune system, contact your health provider or your child’s provider to see what they recommend.

• Primary immune deficiency diseases (a list is available here)

• Cancers (solid tumors or blood cancers like leukemia and lymphoma) currently being treated with any treatment that reduces immune response, or treated in the past two years with a stem cell (bone marrow) transplant or CAR-T therapy

• Organ transplant for any condition (liver, heart, kidney, lung, pancreas) now taking anti-rejection medications

• HIV infection or AIDS

• Chronic use of corticosteroids such as prednisone, especially high doses equivalent or larger than 20 milligrams of prednisone per day

• TNF blockers such as Remicade, Enbrel, Humira, Cimzia, and Simponi, and other biologic agents that suppress or modify the immune response in order to treat an autoimmune diseases such as lupus, rheumatoid arthritis, Crohn’s disease, ulcerative colitis, psoriasis or other condition

• People with end-stage kidney disease and people on dialysis

• Anyone who has had their spleen removed for any reason

Other options for all at-risk teens and adults

Rockwell said that individuals whose health providers do not yet recommend a third dose for them should refrain from seeking a third dose at this time.

But, she adds, recommendations could change in future to include them as well. The CDC committee she serves on will also examine the issue of booster shots for other individuals.

She also noted another new FDA approval that could help immunocompromised people, and others over the age of 12 who aren’t fully vaccinated and have risk factors for severe COVID-19.

The FDA just approved the use of monoclonal antibody therapy as a preventive therapy, for high risk people who know they’ve been exposed to an infected person or live in a facility where someone has gotten COVID-19.