Predictors of lower response to COVID19 vaccine in people living with HIV. A 6-month follow-up study

Clinical trials demonstrated efficacy and safety of COVID-19 vaccines, although enrolment of immunocompromised individuals, including people living with HIV (PLWH), has been limited. Although cellular immunity is not negligible, recent evidence suggests a strong correlation between neutralising antibody titre and overall protection against infection. Our study aimed to identify potential predictors of lower response to vaccine in PLWH. We conducted a prospective study at the Padua University Teaching Hospital, Italy. Participants were vaccinated with a BNT162b2 2-dose schedule in early 2021. Non-naïve to SARS-CoV-2 were excluded. Anti-S titres were assessed using AdviseDx SARS-CoV-2 IgG II quantitative CMIA assay at 30, 90 and 180 days after completion of vaccination. Non-response was defined as < 50 AU/mL and lower response as the lowest quartile. Information on age, sex, BMI, comorbidities, CD4 count, CD4/CD8, viral load was collected. The association between predictors and lower response was assessed using logistic and linear regression. We enrolled 180 individuals (15 excluded). Mean age 54.0±11.2 years; 17% females; 23% showed CD4 count <500 (none <200), while 18.2% CD4/CD8 <0.5. All responded to vaccine at any follow-up time. Lower response was associated with dyslipidaemias (AOR 4.75; 95%CI: 1.39-16.20; 30 days) and diabetes (AOR 7.11; 95%CI: 1.10-46.10; 90 days), while 1-unit increase in BMI was associated with reduced risk (AOR 0.78; 95%CI 0.64-0.95; 90 days). No correlation was found between anti-S titre and CD4 count (β -0.057; p 0.52), CD4/CD8 (β 0.050; p 0.57) nor viral load (β -0.001; p 0.99). Response to vaccine is good and sustained in well controlled PLWH. Dyslipidaemias and diabetes are associated with a non-concerning lower response. Increased BMI as protective factor may reflect the effect of good nutritional status. Using CD4 count, CD4/CD8 or viral load does not appear to help predict vaccine response in well controlled HIV. KEY MESSAGES: • Well controlled People Living With HIV (PLWH) respond well to BNT162b2 vaccine, and neutralising antibody titres are maintained for up to 6 months after primary vaccination. • PLWH with dyslipidaemias and diabetes have lower antibody persistence, although always above the threshold. Good nutritional status may contribute to longer antibody persistence.