COVID-19 vaccine efficacy in participants with weakened immune systems from four randomized-controlled trials

BACKGROUND

Although the SARS-CoV-2 vaccines are highly efficacious at preventing severe disease in the general population, current data are lacking regarding vaccine efficacy (VE) for individuals with mild immunocompromising conditions.

METHODS

A post-hoc, cross-protocol analysis of participant-level data from the blinded phase of four randomized, placebo-controlled, COVID-19 vaccine phase 3 trials (Moderna, AstraZeneca, Janssen, and Novavax) was performed. We defined a "tempered immune system" (TIS) variable via a consensus panel based on medical history and medications to determine VE against symptomatic and severe COVID-19 cases in TIS participants versus non-TIS (NTIS) individuals starting at 14 days after completion of the primary series through the blinded phase for each of the four trials. An analysis of participants living with well-controlled HIV was conducted using the same methods.

RESULTS

3,852/30,351 (12.7%) Moderna participants, 3,088/29,868 (10.3%) Novavax participants, 3,549/32,380 (11.0%) AstraZeneca participants, and 5,047/43,788 (11.5%) Janssen participants were identified as having a TIS. Most TIS conditions (73.9%) were due to metabolism and nutritional disorders. Vaccination (versus placebo) significantly reduced the likelihood of symptomatic and severe COVID-19 for all participants for each trial. VE was not significantly different for TIS participants vs NTIS for either symptomatic or severe COVID-19 for each trial, nor was VE significantly different in the symptomatic endpoint for participants with HIV.

CONCLUSIONS

For individuals with mildly immunocompromising conditions, there is no evidence of differences in VE against symptomatic or severe COVID-19 compared to those with non-tempered immune systems in the four COVID-19 vaccine randomized controlled efficacy trials.

Protein dose-sparing effect of AS01B adjuvant in a randomized preventive HIV vaccine trial of ALVAC-HIV (vCP2438) and adjuvanted bivalent subtype C gp120

BACKGROUND

HVTN 120 is a phase 1/2a randomized double-blind placebo-controlled HIV vaccine trial that evaluated the safety and immunogenicity of ALVAC-HIV (vCP2438) and MF59- or AS01B-adjuvanted bivalent subtype C gp120 Env protein at two dose levels in healthy HIV-uninfected adults. Trial registration URL https://clinicaltrials.gov/ct2/show/NCT03122223 and registration number NCT03122223.

METHODS

Participants received ALVAC-HIV (vCP2438) alone or placebo at months 0 and 1. At months 3 and 6, participants received either placebo, ALVAC-HIV (vCP2438) with 200μg of bivalent subtype C gp120 adjuvanted with MF59 or AS01B, or ALVAC-HIV (vCP2438) with 40μg of bivalent subtype C gp120 adjuvanted with AS01B. Primary outcomes were safety and immune responses.

RESULTS

We enrolled 160 participants, 55% females, 18-40 years old (median age 24 years) of whom 150 received vaccine and 10 placebo. Vaccines were generally safe and well tolerated. At months 6.5 and 12, CD4+ T-cell response rates and magnitudes were higher in the AS01B-adjuvanted groups than in the MF59-adjuvanted group. At month 12, HIV-specific Env-gp120 binding antibody response magnitudes in the 40μg gp120/AS01B group were higher than in either of the 200μg gp120 groups.

CONCLUSIONS

The 40μg dose gp120/AS01B regimen elicited the highest CD4+ T-cell and binding antibody responses.

Neutralization profiles of HIV-1 viruses from the VRC01 Antibody Mediated Prevention (AMP) trials

The VRC01 Antibody Mediated Prevention (AMP) efficacy trials conducted between 2016 and 2020 showed for the first time that passively administered broadly neutralizing antibodies (bnAbs) could prevent HIV-1 acquisition against bnAb-sensitive viruses. HIV-1 viruses isolated from AMP participants who acquired infection during the study in the sub-Saharan African (HVTN 703/HPTN 081) and the Americas/European (HVTN 704/HPTN 085) trials represent a panel of currently circulating strains of HIV-1 and offer a unique opportunity to investigate the sensitivity of the virus to broadly neutralizing antibodies (bnAbs) being considered for clinical development. Pseudoviruses were constructed using envelope sequences from 218 individuals. The majority of viruses identified were clade B and C; with clades A, D, F and G and recombinants AC and BF detected at lower frequencies. We tested eight bnAbs in clinical development (VRC01, VRC07-523LS, 3BNC117, CAP256.25, PGDM1400, PGT121, 10-1074 and 10E8v4) for neutralization against all AMP placebo viruses (n = 76). Compared to older clade C viruses (1998-2010), the HVTN703/HPTN081 clade C viruses showed increased resistance to VRC07-523LS and CAP256.25. At a concentration of 1μg/ml (IC80), predictive modeling identified the triple combination of V3/V2-glycan/CD4bs-targeting bnAbs (10-1074/PGDM1400/VRC07-523LS) as the best against clade C viruses and a combination of MPER/V3/CD4bs-targeting bnAbs (10E8v4/10-1074/VRC07-523LS) as the best against clade B viruses, due to low coverage of V2-glycan directed bnAbs against clade B viruses. Overall, the AMP placebo viruses represent a valuable resource for defining the sensitivity of contemporaneous circulating viral strains to bnAbs and highlight the need to update reference panels regularly. Our data also suggests that combining bnAbs in passive immunization trials would improve coverage of global viruses.

The human tissue-resident CCR5+ T cell compartment maintains protective and functional properties during inflammation

CCR5 is thought to play a central role in orchestrating migration of cells in response to inflammation. CCR5 antagonists can reduce inflammatory disease processes, which has led to an increased interest in using CCR5 antagonists in a wide range of inflammation-driven diseases. Paradoxically, these antagonists appear to function without negatively affecting host immunity at barrier sites. We reasoned that the resolution to this paradox may lie in the CCR5⁺ T cell populations that permanently reside in tissues. We used a single-cell analysis approach to examine the human CCR5⁺ T cell compartment in the blood, healthy, and inflamed mucosal tissues to resolve these seemingly contradictory observations. We found that 65% of the CD4 tissue-resident memory T (TRM) cell compartment expressed CCR5. These CCR5⁺ T_RM cells were enriched in and near the epithelial layer and not only limited to T_H1-type cells but also contained a large T_H17-producing and a stable regulatory T cell population. The CCR5⁺ T_RM compartment was stably maintained even in inflamed tissues including the preservation of T_H17 and regulatory T cell populations. Further, using tissues from the CHARM-03 clinical trial, we found that CCR5⁺ T_RM are preserved in human mucosal tissue during treatment with the CCR5 antagonist Maraviroc. Our data suggest that the human CCR5⁺ T_RM compartment is functionally and spatially equipped to maintain barrier immunity even in the absence of CCR5-mediated, de novo T cell recruitment from the periphery.

Dermal-resident versus recruited γδ T cell response to cutaneous vaccinia virus infection

The study of T cell immunity at barrier surfaces has largely focused on T cells bearing the αβ TCR. However, T cells that express the γδ TCR are disproportionately represented in peripheral tissues of mice and humans, suggesting they too may play an important role responding to external stimuli. In this article, we report that, in a murine model of cutaneous infection with vaccinia virus, dermal γδ T cell numbers increased 10-fold in the infected ear and resulted in a novel γδ T cell population not found in naive skin. Circulating γδ T cells were specifically recruited to the site of inflammation and differentially contributed to dermal populations based on their CD27 expression. Recruited γδ T cells, the majority of which were CD27(+), were granzyme B(+) and made up about half of the dermal population at the peak of the response. In contrast, recruited and resident γδ T cell populations that made IL-17 were CD27(-). Using a double-chimera model that can discriminate between the resident dermal and recruited γδ T cell populations, we demonstrated their divergent functions and contributions to early stages of tissue inflammation. Specifically, the loss of the perinatal thymus-derived resident dermal population resulted in decreased cellularity and collateral damage in the tissue during viral infection. These findings have important implications for our understanding of immune coordination at barrier surfaces and the contribution of innate-like lymphocytes on the front lines of immune defense.