Pfizer and Moderna COVID vaccines trigger the same immune response in people with HIV as those without HIV

According to the results of studies conducted into the Pfizer and Moderna COVID-19 vaccines, experts have concluded that the two vaccines cause a strong immune response in people living with HIV, reports Aidsmap (https://www.aidsmap.com/news/aug-2021/pfizer-and-moderna-covid-19-vaccines-produce-strong-antibody-responses-people-hiv).

In some countries, people living with HIV are being given priority in the vaccination rollout. But until now there has been little accurate information on whether HIV-induced immunosuppression can lead to a weaker response to the vaccines.

As such, many vaccine companies are now evaluating their products with different groups of people. Earlier this year, two research groups, reported that there was no difference in immune responses to the Oxford / AstraZeneca vaccine between people living with, and without, HIV.

One new study looked into the Pfizer and Moderna vaccines, both based on mRNA technology. There is no reason to believe that mRNA vaccines are less effective for people living with HIV.

Two separate research groups at the Johns Hopkins University School of Medicine in Baltimore studied the response of people living with HIV to Pfizer or Moderna vaccines.

Study 1

The first study evaluated the evolution of antibody response after first and second doses in 5 people living with HIV receiving the Pfizer vaccine and 9 people receiving the Moderna vaccine. 13 men and 1 woman participated in the study, with an average age of 62 years. All participants had been receiving antiretroviral therapy for at least six months. All but two participants had a CD4 count above 500 cells/mm3.

Blood samples were taken to measure antibodies on average 21 days after first vaccination, and 29 days after the second vaccination. 

The average timer of antibodies after the first vaccination was 76 units/ml, and after the second vaccination all but one participants had an antibody titer of about 250 units/ml - the remaining participant had 236 units/ml.

Researchers note that the antibody response amongst the participants was similar to that observed in HIV-negative people and much better than in people with weakened immunity or those who took cancer drugs that affect the production of lymphocytes.

Study 2

Another group from Johns Hopkins University School of Medicine studied antibodies and cellular immune response. In addition to supporting antibody reactions, cellular immune responses to SARS-CoV-2 are critical to preventing severe illness, experts believe.

Scientists compared antibodies and cellular immune response in 12 people living with HIV and 17 HIV negative people at between 7 and 17 days after the second vaccination with the Pfizer vaccine. 

All participants were taking antiretroviral treatment. Seven of twelve participants were women. The average CD4 count of the participants was 913, three had low-level viremia (from 20 to 70 copies/ml), while the rest were undetectable (below 20 copies/ml).

The participants with HIV did not have significantly lower antibody titers compared to HIV-negative people, and they did not have lower levels of neutralising antibodies to alpha, beta and gamma variants. The study did not address the responses to the Delta variant, which is now the dominant strain.

The researchers reported that there was no difference in strength or breadth of cellular immune response between people living with HIV and HIV negative patients, although the average age of people with HIV was 52 years, compared to 41 years in the HIV negative group.

However, the authors of the study argue that additional studies of vaccine responses in people with lower CD4 cells are needed to confirm that people with low CD4 counts react to vaccinations as well as people living with HIV with higher CD4 counts.