Antibody response durability following three-dose COVID-19 vaccination in people with HIV receiving suppressive ART (preprint)

Background: Limited data exist regarding longer-term antibody responses following three-dose COVID-19 vaccination, and the impact of a first SARS-CoV-2 infection during this time, in people living with HIV (PLWH) receiving suppressive antiretroviral therapy (ART). We quantified wild-type-(WT), Omicron BA.1- and Omicron BA.5-specific responses up to six months post-third dose in 64 PLWH and 117 controls who remained COVID-19-naive or experienced their first SARS-CoV-2 infection during this time. Design: Longitudinal observational cohort. Methods: We quantified WT- and Omicron-specific Anti-Spike receptor-binding domain IgG concentrations, ACE2 displacement activities and live virus neutralization at one, three and six months post-third vaccine dose. Results: Third doses boosted all antibody measures above two-dose levels, but BA.1-specific responses remained significantly lower than WT-specific ones, with BA.5-specific responses lower still. Serum IgG concentrations declined at similar rates in COVID-19-naive PLWH and controls post-third dose (median WT- and BA.1-specific half-lives were between 66-74 days for both groups). Antibody function also declined significantly yet comparably between groups: six months post-third dose, BA.1-specific neutralization was undetectable in >80% of COVID-19 naive PLWH and >90% of controls. Breakthrough SARS-CoV-2 infection boosted antibody concentrations and function significantly above vaccine-induced levels in both PLWH and controls, though BA.5-specific neutralization remained significantly poorer than BA.1 even post-breakthrough. Conclusions: Following three-dose COVID-19 vaccination, antibody response durability in PLWH receiving ART is comparable to controls. PLWH also mounted strong responses to breakthrough infection. Due to temporal response declines however, COVID-19-naive individuals, regardless of HIV status, would benefit from a fourth dose within 6 months of their third.

Brief Report: Impact of age and SARS-CoV-2 breakthrough infection on humoral immune responses after three doses of COVID-19 mRNA vaccine (preprint)

Longitudinal immune response data following three-dose COVID-19 mRNA vaccination remain limited, particularly in older adults and those experiencing their first SARS-CoV-2 infection. We quantified wild-type- and Omicron-specific antibody concentrations and virus neutralization activity up to six months post-third-dose in COVID-19-naive adults aged 24-98 years. Among participants who remained COVID-19-naive, antibody concentrations were comparable between age groups over time. Omicron-specific neutralization declined more rapidly in older adults, and at six months was undetectable in 56% and 96% of COVID-19-naive younger and older adults, respectively. Post-vaccine SARS-CoV-2 breakthrough infections increased wild-type- and Omicron-specific responses above three-dose vaccination alone, illustrating beneficial hybrid immunity.

People with HIV receiving suppressive antiretroviral therapy show typical antibody durability after dual COVID-19 vaccination, and strong third dose responses (preprint)

Background: Longer-term humoral responses to two-dose COVID-19 vaccines remain incompletely characterized in people living with HIV (PLWH), as do initial responses to a third dose. Methods: We measured antibodies against the SARS-CoV-2 spike protein receptor-binding domain, ACE2 displacement and viral neutralization against wild-type and Omicron strains up to six months following two-dose vaccination, and one month following the third dose, in 99 PLWH receiving suppressive antiretroviral therapy, and 152 controls. Results: Though humoral responses naturally decline following two-dose vaccination, we found no evidence of lower antibody concentrations nor faster rates of antibody decline in PLWH compared to controls after accounting for sociodemographic, health and vaccine-related factors. We also found no evidence of poorer viral neutralization in PLWH after two doses, nor evidence that a low nadir CD4+ T-cell count compromised responses. Post-third-dose humoral responses substantially exceeded post-second-dose levels, though anti-Omicron responses were consistently weaker than against wild-type. Nevertheless, post-third-dose responses in PLWH were comparable to or higher than controls. An mRNA-1273 third dose was the strongest consistent correlate of higher post-third-dose responses. Conclusion: PLWH receiving suppressive antiretroviral therapy mount strong antibody responses after two- and three-dose COVID-19 vaccination. Results underscore the immune benefits of third doses in light of Omicron.

Older Adults Mount Less Durable Humoral Responses to a Two-dose COVID-19 mRNA Vaccine Regimen, but Strong Initial Responses to a Third Dose (preprint)

Background. Two-dose mRNA vaccines reduce COVID-19 related hospitalization and mortality, but immune protection declines over time. As such, third vaccine doses are now recommended, particularly for older adults. We examined immune response durability up to 6 months after two vaccine doses, and immunogenicity after a third vaccine dose, in 151 adults ranging in age from 24 to 98 years. Methods. Specimens were collected from 81 healthcare workers (median age 41 years), 56 older adults (median 78 years) and 14 COVID-19 convalescent individuals (median 48 years), at one, three and six months following the second dose, and from 15 HCW, 28 older adults and 3 convalescent individuals at one month following a third dose. Binding antibodies to the SARS-CoV-2 spike receptor binding domain were quantified using a commercial immunoassay. Virus neutralizing activity was assessed using a live SARS-CoV-2 infection assay. Results. Compared to healthcare workers, older adults displayed ~0.3 log10 lower peak binding antibodies one month after the second dose (p<0.0001) and modestly faster rates of antibody decline thereafter (p=0.0067). A higher burden of chronic health conditions was independently associated with faster rates of antibody decline after correction for age, sociodemographic factors, and vaccine-related variables. Peak neutralizing activity was 4-fold lower in older adults one month after the second dose (p<0.0001) and became undetectable in the majority of individuals by six months. One month after a third dose, binding antibodies and neutralizing activities surpassed peak values achieved after two doses in both healthcare workers and older adults, and differences between these groups were no longer statistically significant. Compared to both naive groups, convalescent individuals displayed slower rates of binding antibody decline (p<0.006) and maintained higher neutralizing activity six months after the second dose. Conclusions. Immune responses to two-dose COVID-19 mRNA vaccines are overall weaker in older adults, and also decline more quickly over time, compared to younger adults. A third COVID-19 mRNA vaccine dose enhanced binding and neutralizing antibodies to levels higher than those observed after two vaccine doses, but the rate of decline of these responses should be monitored, particularly in older adults with a higher burden of chronic health conditions.