As the pandemic continues, we continue to learn more about how COVID-19 (and SARS-CoV-2, the virus that causes it) is affecting people living with HIV. Now, some recently released study results are showing that some people living with HIV have lower than expected antibody levels after receiving the Pfizer or Moderna COVID-19 vaccines.
The findings were presented recently at the virtual IDWeek conference, a joint annual meeting of the Infectious Diseases Society of America (IDSA), Society for Healthcare Epidemiology of America (SHEA), the HIV Medicine Association (HIVMA), the Pediatric Infectious Diseases Society (PIDS), and the Society of Infectious Diseases Pharmacists (SIDP).
Dr. Matthew Spinelli of the University of California at San Francisco and his teammates evaluated immune responses to COVID-19 vaccination according to HIV status and mRNA vaccine type, according to NAM AIDSMap. The study also showed that those with a detectable viral load or a low CD4 T-cell count were at greater risk for diminished response, supporting a third vaccine dose for these individuals.
The researchers studied stored lab samples from 100 adults who received two doses of the Pfizer or Moderna vaccines at the Ward 86 outpatient HIV clinic at San Francisco General Hospital during April 2021. Their results were compared with 100 HIV-negative patients receiving care for other chronic medical conditions. People with known prior SARS-CoV-2 infections were excluded from the study.
Most of the participants were male (90 percent) and the median age was 59 years. Seventy-five percent received the Pfizer vaccine and the rest received the Moderna vaccine. Immune response was assessed about 35 days after the second dose. For those living with HIV, the median CD4 count was 511, and five people had a detectable viral load (HIV RNA above 200 copies). Spinelli and his team noted, “All seven people with a CD4 count below 200 were non-responders.”
The study ultimately found that people living with HIV were more than twice as likely to have a poor vaccine response. IgG antibody non-response was seen in 12 percent of HIV-positive people, compared with 5 percent of HIV-negative people. In addition, IgG antibody levels were 43 percent lower in HIV-positive people than with HIV-negative people.
The findings did differ depending upon which vaccine was used. People who received the Pfizer shot had a 66 percent lower IgG antibody level response than Moderna recipients—and actually, none of the people found to be non-responders had received the Moderna vaccine.
One limitation of the study is that it did not measure T-cell responses, which can provide longer-term protection as antibody levels eventually drop off. The study also did not look at changes in participants’ immune response over time, like how many people developed symptomatic COVID-19 or required hospitalization.
“People living with HIV had lower than expected response to mRNA SARS-CoV-2 vaccines, with the highest non-response among those with low CD4 counts, unsuppressed HIV RNA, and those who received the BNT162b2 [Pfizer] vaccine,” the researchers stated, and noted they planned to continue researching this issue.