There's mounting research to suggest that protecting people who are immuno-compromised from getting COVID is important not just for their sake – it could be critical in the effort to end the pandemic for everyone.
The evidence comes from two separate strands of studies.
Dr. Laura McCoy has been doing the first type. She's an infectious disease researcher at University College London.
"The group of people that I'm particularly interested in are those living with HIV," she says.
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, "all of our participants had really quite well-controlled HIV."
Normally HIV attacks the immune system. But these patients were on anti-HIV medications that were suppressing HIV's impact. "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," says McCoy.
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, says McCoy, "when we looked at their blood there were very few functional b-cells or t-cells." Both are 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, "we actually couldn't see any measurable levels of anti-coronavirus antibody in the blood," says McCoy.
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-19 antibodies in response to the vaccine.
"That's really quite extraordinary," says McCoy.
These results, published in the journal The Lancet this month, match similar findings that the vaccines may not be effective for people who are immuno-compromised for other reasons such as individuals with cancer or organ transplant recipients who are taking immuno-suppressing drugs to keep their bodies from rejecting the transplant.
Dr. Salim Abdool Karim directs South Africa's Centre for the AIDS Programme of Research. He says this research suggests that a lot of people are at risk around the world. "Most countries will have immuno-suppressed individuals," he notes.
And Abdool Karim says it's time to connect the dots to the second category of research regarding immuno-compromised people and COVID-19.
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.
"In the course of that time the virus underwent multiple mutations," says Abdool Karim. 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.
"So essentially this HIV-positive woman became a cauldron for the creation of a whole lot of new variants," he says. "She literally re-created the steps."
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: "Immuno-suppressed individuals are really important in this pandemic."
Protecting them needs to be made a top priority — to keep them safe and to slow the emergence of variants, he says.
There are potential solutions.: For instance, a recent study of organ transplant patients who were on immuno-suppressing 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.
What's important, 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."