Reduced COVID Vaccine Response in People With HIV

People living with HIV had lower than expected antibody levels after receiving COVID-19 vaccines, according to study results presented at the 2021 virtual IDWeek conference.

In this exclusive MedPage Today video, study author Matthew Spinelli, MD, of the University of California San Francisco, discusses the clinical implications.

Following is a transcript of his remarks:

With the Pfizer EUA [emergency use authorization] for a booster dose, there is a lot of interest in, What are the populations that could potentially benefit from supplemental vaccination doses? Initially there was some more cheery data that people living with HIV might be at lower risk of COVID-19 severe disease. But later data has, I think, relatively clearly confirmed that people living with HIV are at higher risk of severe COVID-19. And the hope is that vaccines will attenuate that. But we have very little data on what is the immune response to vaccination among people living with HIV.

The little data that’s out there, there was a study with AstraZeneca vaccination that showed similar responses by HIV status, which I think was somewhat reassuring. However, that study restricted it to people who had CD4 counts above 350. It was the original vaccine efficacy study. They wanted to make sure the vaccine would not be compromised by poor immune response. There’s a little bit of data on the mRNA Vaccines, but I think it’s still pretty preliminary.

We set out to have a first look at this question. What we did is when people in our clinic, in our large HIV clinic, did their lab testing, we basically saved residual samples, when they were getting their chemistries — there’s always leftovers. We matched our patients to people in the general medicine clinics getting care for chronic conditions, and we matched them on the same mRNA vaccine received, the same sex, the same number of days since the second vaccine, since the completion of the vaccine series, and also age plus or minus 5 years. So we had a very well-matched group for this kind of cross-sectional look at what were the antibody responses to the vaccination.

We looked at both IgG antibodies towards the SARS-CoV-2 receptor binding domain. And also we did a test called a surrogate virus neutralization test, which is looking at the ability of these antibodies to sort of functionally neutralize that binding to the receptor binding domain. And there was a trend towards decreased IgG response among people living with HIV (the P value for that was 0.08). And then for surrogate virus neutralization, 24% of the people living with HIV did not produce surrogate virus neutralizing titers, compared to 12%. And that was statistically significant, that difference.

So then we wanted to understand, in those who did respond, were there kind of actual differences in the levels of the antibodies produced, because that could give us a sign of how robust is the response and a window — not complete — but a window into how long these antibodies persist.

And what we found is that there were lower IgG levels in those who did respond among people living with HIV. I will tell you exactly how much — there were 43% lower IgG levels, but no difference in surrogate virus neutralization. So for whatever reason with that test, it was more of a threshold effect.

After we had seen these differences by HIV status, we wanted to understand what are the subgroups among people living with HIV who we should particularly be concerned might not respond as well. And that included people with unsuppressed viral loads, as you would expect. And, interestingly, continuous CD4 counts — so for every 100-cell increase in the CD4 count, the IgG levels were 28% higher. So, I think in this more diverse population, which had more people with lower CD4 counts, there definitely is a signal there. And I think that’s why our study differs from some of the prior studies, and that our clinic has more people in it. It’s a municipal clinic that sees the safety net population, has more people with lower CD4 counts.

So the final finding, which I think is interesting is that actually there were quite a bit lower responses among those who had Pfizer/BioNTech vaccine versus the Moderna vaccine. So the IgG levels were actually 66% lower among those who had the Pfizer versus the Moderna. So, I think that’s an interesting finding. I think the conclusions we can draw from this is that there is some initial evidence that the magnitude and the response may be a little bit lower amongst some people living with HIV who get mRNA vaccination. I think the EUA to provide boosting among Pfizer recipients seems reasonable. And I think people with HIV are a group, certainly those with lower CD4 counts, I think should be prioritized. Whether or not people who got the Moderna vaccine need boosting is not clear to me yet. I think we need more data given that they seem to respond a little bit better, at least immunologically.