Humoral immune responses to COVID-19 vaccination in people living with HIV on suppressive antiretroviral therapy (preprint)

ABSTRACT

Background. Our understanding of COVID-19 vaccine immune responses in people living with HIV (PLWH) remains incomplete. Methods. We measured circulating antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and ACE2 displacement activities after one and two COVID-19 vaccine doses in 100 adult PLWH and 152 controls. Results. All PLWH were receiving suppressive antiretroviral therapy, with median CD4+ T-cell counts of 710 (IQR 525-935) cells/mm3. Median nadir CD4+ T-cell counts were 280 (IQR 120-490) cells/mm3, and ranged as low as 9 cells/mm3. After adjustment for sociodemographic, health and vaccine-related variables, HIV infection was associated with 0.2 log10 lower anti-RBD antibody concentrations (p=0.03) and ~7% lower ACE2 displacement activity (p=0.037) after one vaccine dose. Following two vaccine doses however, the association between HIV and weaker responses no longer remained. Rather, older age, a higher burden of chronic health conditions, and having received two ChAdOx1 doses (as opposed to a heterologous or dual mRNA vaccine regimen) were the most significant correlates of weaker humoral responses. No significant association was observed between the most recent or nadir CD4+ T-cell counts and responses to COVID-19 vaccination in PLWH following two vaccine doses. Conclusions. These results suggest that PLWH whose viral loads are well-controlled on antiretroviral therapy and whose CD4+ T-cell counts are in a healthy range will generally not require a third COVID-19 vaccine dose as part of their initial immunization series, though other factors such as older age, co-morbidities, type of initial vaccine regimen and durability of vaccine responses will influence when this group may benefit from additional doses. Further studies of PLWH who are not receiving antiretroviral treatment and/or who have low CD4+ T-cell counts are needed.