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Why 3rd doses shouldn’t wait for people with compromised immune systems

Additional vaccination shots may be arriving for the general public as soon as September, but for those with special health needs, it may not be advisable to wait for a booster shot to protect against COVID-19.

The terms “booster shot” and “third dose” are being used interchangeably, but there is a difference. That’s especially important for people who are immunocompromised. The Centers for Disease Control and Prevention is recommending they receive an additional dose as soon as medically possible.

But with the U.S. surgeon general outlining plans Wednesday for booster shots next month for the general public, it can be confusing to sort out who should start thinking about a booster in the fall and who should get a third shot now.

A booster is administered after a person’s immunity decreases or after an additional exposure (think: tetanus). A third dose is a part of a recommended course of vaccines, meant to be delivered on a schedule (think: hepatitis). Healthy people usually have a moderate response to the first dose of a COVID-19 vaccine, and then a stronger response to the second. People who are immune-compromised may need more doses to get the same level of virus-fighting antibodies that others have.

The FDA recommends a third dose of a COVID-19 vaccine for people who are moderately or severely immunocompromised. That includes those being treated for cancer, have an advanced or untreated HIV infection, have had an organ transplant, or who for other reasons have suppressed or compromised immune systems. The Oregon Health Authority recommended the same after a working group of scientists representing West Coast states also issued their approval.

A list of qualifying conditions can be found here, but the best way to find out if you should get a third dose of the COVID-19 vaccine is to talk to your doctor.

When should I get a third dose?

Current guidance from the CDC says to wait at least 28 days between receiving the second and third doses.

Health care workers have known for a while that vaccines don’t work as well in people with certain conditions. The delta variant of the coronavirus has made that worse.A recent study by the CDC found that immunocompromised people make up more than 40% of hospitalized breakthrough infections. Other research suggests that a third dose does increase the number of antibodies immunocompromised people create. Giving the immunocompromised a third dose could help keep more people out of the hospital.

The CDC currently recommends that people stick with the vaccines they already received. So if you started with Moderna, stay with Moderna. Same with Pfizer. There’s not enough data on how mixing vaccines could impact efficacy.

Right now? Nothing. The CDC says there is currently not enough evidence to tell if immunocompromised people who got the Johnson & Johnson vaccine will benefit from another dose. But health officials expect an additional dose will be recommended.

Booster shots will be made available starting in mid-September. They will go to doctors and nurses first. The CDC says that boosters are not necessary until at least eight months have passed since receiving a second dose.

CDC data shows that both the Pfizer and Moderna vaccines are just as effective at preventing hospitalization from the delta variant as they were against other variants - but that’s only after removing immunocompromised people from the data set. Data about preventing infection is harder to interpret. It does show that more vaccinated people are getting sick now than were previously, but mask mandates have been lifted in many places, and the delta variant is more contagious than others. Some scientists say that even though it may appear that immunity is waning, it could just be because the landscape of the virus is so different now.

The FDA has approved booster shots for all adults. But World Health Organization officials say that the U.S. and other rich countries should hold off on booster shots until more countries have vaccinated their adults.

Copyright 2021 Oregon Public Broadcasting

Erin Ross