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The coronavirus pandemic presents different challenges for those with weakened immune systems. That includes patients taking immunosuppressant drugs for cancer or organ transplants and anyone with uncontrolled HIV infections. Research suggests that protecting immunocompromised people from COVID could be a key to ending the pandemic. NPR's Nurith Aizenman explains.
NURITH AIZENMAN, BYLINE: Dr. Laura McCoy is an infectious disease researcher at University College London.
LAURA MCCOY: The group of people that I'm particularly interested in are those living with HIV.
AIZENMAN: She's been studying how well their immune systems respond to vaccines against COVID-19, specifically the Pfizer vaccine. So far, it's worked quite well for HIV-positive people, but there's a catch. In her studies...
MCCOY: All of our participants had really quite well-controlled HIV.
AIZENMAN: Normally, HIV attacks the immune system, but these patients were on anti-HIV medications that were suppressing HIV's impact.
MCCOY: What we hadn't yet seen was how people's immune response was affected when their HIV was effectively out of control because they weren't on medication.
AIZENMAN: Then, in a clinic she was working with, an HIV-positive patient came in who was not on any meds. The HIV virus had decimated this person's immune system. For instance...
MCCOY: There were very few functional B cells or T cells.
AIZENMAN: Crucial players in the immune system - and as it happened, just 16 days earlier, this person had gotten their second dose of the Pfizer vaccine. Typically, two weeks after the second dose, a person's blood is teeming with antibodies against COVID. But with this person...
MCCOY: We actually couldn't see any measurable levels of anti-coronavirus antibody in the blood.
AIZENMAN: Even after 44 days, once this person had been put on HIV meds and their immune system had recovered, they still had not produced any COVID antibodies in response to the vaccine.
MCCOY: That's really quite extraordinary.
AIZENMAN: These results, published in the journal The Lancet this month, matched similar recent findings that the vaccines may not be effective for people who are immunocompromised for other reasons - cancer patients and organ transplant recipients on immunosuppressing drugs. Dr. Salim Abdool Karim directs South Africa's Center for the AIDS Program of Research. He says this suggests in countries around the world, a lot of people are at risk.
SALIM ABDOOL KARIM: Most countries will have immunosuppressed individuals.
AIZENMAN: And he says it's time to connect the dots to a wider problem. Specifically, a team that includes researchers at the center Abdool Karim leads recently followed the case of a woman in South Africa who was infected with the coronavirus at a time when her HIV was uncontrolled. It took her body seven months to clear the coronavirus.
ABDOOL KARIM: In the course of that time, the virus undergoes multiple mutations.
AIZENMAN: And step by step, these mutations morphed the virus into a version of the variants of concern that have fueled new surges across the world.
ABDOOL KARIM: This HIV-positive woman became a cauldron for the creation of a whole lot of new variants. She literally recreated the steps.
AIZENMAN: And that finding echoes a handful of similar studies. Abdool Karim, who also co-chairs South Africa's advisory committee on COVID-19, says his takeaway is this.
ABDOOL KARIM: Immunosuppressed individuals are really important in this pandemic.
AIZENMAN: Protecting them needs to be made a top priority for their own sake and to slow the emergence of variants. And there are potential solutions. For instance, a recent study of organ transplant patients who were on immunosuppressing drugs found that giving them a third dose of either the Pfizer or Moderna vaccine did have some effect. Similarly, McCoy's work on HIV-positive patients suggests if you make sure a person's HIV has been treated before you give them a COVID vaccine, the vaccine will work. The key, says Abdool Karim, will be to ramp up research on all this. This is a new scientific puzzle, he says, and we've only just begun putting the pieces together.
Nurith Aizenman, NPR News.
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