Determinants of humoral and cellular immune responses to three doses of mRNA SARS-CoV-2 vaccines in older adults: a longitudinal cohort study

Longitudinal Analysis of Nursing Home Residents' T-Cell Responses After SARS-CoV-2 mRNA Vaccinations Shows Influence of Biological Sex and Infection History

BACKGROUND

Vaccines and vaccine boosting have blunted excess morbidity and mortality from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in older nursing home residents (NHR). However, the impact of repeated vaccination on the T-cell response based on biological sex and prior infection of NHR remain understudied.

METHODS

We examined T-cell responses to SARS-CoV-2 mRNA vaccines in a cohort of NHR and healthcare workers (HCW) over 2 years. We used interferon-γ ELIspot and flow cytometry to assess T-cell response before, 2 weeks, and 6 months after the initial series and each of 2 booster vaccines. We analyzed these data longitudinally with mixed-effect modeling and also examined subsets of our cohorts for additional changes in T-cell effector function.

RESULTS

Prior SARS-CoV-2 infection and female sex contributed to higher T-cell response in NHR but not HCW. When looking across time points, NHR but not HCW with prior infection had significantly higher T-cell responses than infection-naive subjects. These patterns of response were maintained across multiple booster vaccinations.

CONCLUSIONS

These results suggest that the age, multimorbidity, and/or frailty of the NHR cohort may accentuate sex and infection status differences in T-cell response to mRNA vaccination.

Repeated COVID-19 mRNA vaccination results in IgG4 class switching and decreased NK cell activation by S1-specific antibodies in older adults

BACKGROUND

Previous research has shown that repeated COVID-19 mRNA vaccination leads to a marked increase of SARS-CoV-2 spike-specific serum antibodies of the IgG4 subclass, indicating far-reaching immunoglobulin class switching after booster immunization. Considering that repeated vaccination has been recommended especially for older adults, the aim of this study was to investigate IgG subclass responses in the ageing population and assess their relation with Fc-mediated antibody effector functionality.

RESULTS

Spike S1-specific IgG subclass concentrations (expressed in arbitrary units per mL), antibody-dependent NK cell activation, complement deposition and monocyte phagocytosis were quantified in serum from older adults (n = 38-50, 65-83 years) at one month post-second, -third and -fifth vaccination. Subclass distribution in serum was compared to that in younger adults (n = 64, 18-47 years) at one month post-second and -third vaccination. Compared to younger individuals, older adults showed increased levels of IgG2 and IgG4 at one month post-third vaccination (possibly related to factors other than age) and a further increase following a fifth dose. The capacity of specific serum antibodies to mediate NK cell activation and complement deposition relative to S1-specific total IgG concentrations decreased upon repeated vaccination. This decrease associated with an increased IgG4/IgG1 ratio.

CONCLUSIONS

In conclusion, these findings show that, like younger individuals, older adults produce antibodies with reduced functional capacity upon repeated COVID-19 mRNA vaccination. Additional research is needed to better understand the mechanisms underlying these responses and their potential implications for vaccine effectiveness. Such knowledge is vital for the future design of optimal vaccination strategies in the ageing population.

Immunogenicity of BNT162b2 as a first booster after a ChAdOx1 primary series in a Thai geriatric population living with frailty

OBJECTIVES

Impact of frailty towards immunogenicity and reactogenicity of BNT162b2 boosters administered via intramuscular or intradermal routes in a Thai geriatric population DESIGN: Prospective, randomized, open-labeled.

SETTING

Siriraj Hospital, Thailand.

PARTICIPANTS

Geriatric adults aged ≥65 years.

INTERVENTION

10 μg intradermal or 30 μg intramuscular BNT162b2 (Pfizer-BioNTech).

MEASUREMENTS

Anti-SARS-CoV-2 receptor binding domain IgG, neutralizing antibodies (NAb), and interferon-gamma producing cells against Wuhan and Omicron BA.4/5. Analyses were stratified based on participants' Clinical Frailty Scale.

RESULTS

A total of 139 participants were included in the analysis. Two-four weeks post-booster administration, NAb titers against Wuhan but not Omicron BA.4/5 were significantly lower among frail participants than non-frail participants who received intramuscular administration. Spike-specific T cell responses were similar for frail and non-frail participants, regardless of administration route. Frail participants who received intradermal BNT162b2 had fewer local adverse events (AEs), but higher systemic AEs than non-frail participants.

CONCLUSION

Similar immune responses across vaccine routes warrants further evaluation of intradermal BNT162b2 in frail geriatric populations. Frail participants may be more sensitive to reporting systemic AEs.

REGISTRATION OF CLINICAL TRIALS

The parent study was registered under the Thai Clinical Trials Registry (TCTR20220112002).

Heterologous Ad26.COV2.S booster after primary BBIBP-CorV vaccination against SARS-CoV-2 infection: 1-year follow-up of a phase 1/2 open-label trial

BACKGROUND

Inactivated whole-virus vaccination elicits immune responses to both SARS-CoV-2 nucleocapsid (N) and spike (S) proteins, like natural infections. A heterologous Ad26.COV2.S booster given at two different intervals after primary BBIBP-CorV vaccination was safe and immunogenic at days 28 and 84, with higher immune responses observed after the longer pre-boost interval. We describe booster-specific and hybrid immune responses over 1 year.

METHODS

This open-label phase 1/2 study was conducted in healthy Thai adults aged ≥ 18 years who had completed primary BBIBP-CorV primary vaccination between 90-240 (Arm A1; n = 361) or 45-75 days (Arm A2; n = 104) before enrolment. All received an Ad26.COV2.S booster. We measured anti-S and anti-N IgG antibodies by Elecsys®, neutralizing antibodies by SARS-CoV-2 pseudovirus neutralization assay, and T-cell responses by quantitative interferon (IFN)-γ release assay. Immune responses were evaluated in the baseline-seronegative population (pre-booster anti-N < 1.4 U/mL; n = 241) that included the booster-effect subgroup (anti-N < 1.4 U/mL at each visit) and the hybrid-immunity subgroup (anti-N ≥ 1.4 U/mL and/or SARS-CoV-2 infection, irrespective of receiving non-study COVID-19 boosters).

RESULTS

In Arm A1 of the booster-effect subgroup, anti-S GMCs were 131-fold higher than baseline at day 336; neutralizing responses against ancestral SARS-CoV-2 were 5-fold higher than baseline at day 168; 4-fold against Omicron BA.2 at day 84. IFN-γ remained approximately 4-fold higher than baseline at days 168 and 336 in 18-59-year-olds. Booster-specific responses trended lower in Arm A2. In the hybrid-immunity subgroup at day 336, anti-S GMCs in A1 were 517-fold higher than baseline; neutralizing responses against ancestral SARS-CoV-2 and Omicron BA.2 were 28- and 31-fold higher, respectively, and IFN-γ was approximately 14-fold higher in 18-59-year-olds at day 336. Durable immune responses trended lower in ≥ 60-year-olds.

CONCLUSION

A heterologous Ad26.COV2.S booster after primary BBIBP-CorV vaccination induced booster-specific immune responses detectable up to 1 year that were higher in participants with hybrid immunity.

CLINICAL TRIALS REGISTRATION

NCT05109559.

SARS-CoV-2 booster vaccine dose significantly extends humoral immune response half-life beyond the primary series

SARS-CoV-2 lipid nanoparticle mRNA vaccines continue to be administered as the predominant prophylactic measure to reduce COVID-19 disease pathogenesis. Quantifying the kinetics of the secondary immune response from subsequent doses beyond the primary series and understanding how dose-dependent immune waning kinetics vary as a function of age, sex, and various comorbidities remains an important question. We study anti-spike IgG waning kinetics in 152 individuals who received an mRNA-based primary series (first two doses) and a subset of 137 individuals who then received an mRNA-based booster dose. We find the booster dose elicits a 71-84% increase in the median Anti-S half life over that of the primary series. We find the Anti-S half life for both primary series and booster doses decreases with age. However, we stress that although chronological age continues to be a good proxy for vaccine-induced humoral waning, immunosenescence is likely not the mechanism, rather, more likely the mechanism is related to the presence of noncommunicable diseases, which also accumulate with age, that affect immune regulation. We are able to independently reproduce recent observations that those with pre-existing asthma exhibit a stronger primary series humoral response to vaccination than compared to those that do not, and further, we find this result is sustained for the booster dose. Finally, via a single-variate Kruskal-Wallis test we find no difference between male and female humoral decay kinetics, however, a multivariate approach utilizing  Least Absolute Shrinkage and Selection Operator (LASSO) regression for feature selection reveals a statistically significant (p < 1 × 10 - 3 ), albeit small, bias in favour of longer-lasting humoral immunity amongst males.

Cellular Immunity of SARS-CoV-2 in the Borriana COVID-19 Cohort: A Nested Case-Control Study

Our goal was to determine the cellular immune response (CIR) in a sample of the Borriana COVID-19 cohort (Spain) to identify associated factors and their relationship with infection, reinfection and sequelae. We conducted a nested case-control study using a randomly selected sample of 225 individuals aged 18 and older, including 36 individuals naïve to the SARS-CoV-2 infection and 189 infected patients. We employed flow-cytometry-based immunoassays for intracellular cytokine staining, using Wuhan and BA.2 antigens, and chemiluminescence microparticle immunoassay to detect SARS-CoV-2 antibodies. Logistic regression models were applied. A total of 215 (95.6%) participants exhibited T-cell response (TCR) to at least one antigen. Positive responses of CD4+ and CD8+ T cells were 89.8% and 85.3%, respectively. No difference in CIR was found between naïve and infected patients. Patients who experienced sequelae exhibited a higher CIR than those without. A positive correlation was observed between TCR and anti-spike IgG levels. Factors positively associated with the TCR included blood group A, number of SARS-CoV-2 vaccine doses received, and anti-N IgM; factors inversely related were the time elapsed since the last vaccine dose or infection, and blood group B. These findings contribute valuable insights into the nuanced immune landscape shaped by SARS-CoV-2 infection and vaccination.

A 12-month follow-up of the immune response to SARS-CoV-2 primary vaccination: evidence from a real-world study

A real-world population-based longitudinal study, aimed at determining the magnitude and duration of immunity induced by different types of vaccines against COVID-19, started in 2021 by enrolling a cohort of 2,497 individuals at time of their first vaccination. The study cohort included both healthy adults aged ≤65 years and elderly subjects aged >65 years with two or more co-morbidities. Here, patterns of anti-SARS-CoV-2 humoral and cell-mediated specific immune response, assessed on 1,182 remaining subjects, at 6 (T6) and 12 months (T12) after the first vaccine dose, are described. At T12 median anti-Spike IgG antibody levels were increased compared to T6. The determinants of increased anti-Spike IgG were the receipt of a third vaccine dose between T6 and T12 and being positive for anti-Nucleocapside IgG at T12, a marker of recent infection, while age had no significant effect. The capacity of T12 sera to neutralize in vitro the ancestral B strain and the Omicron BA.5 variant was assessed in a subgroup of vaccinated subjects. A correlation between anti-S IgG levels and sera neutralizing capacity was identified and higher neutralizing capacity was evident in healthy adults compared to frail elderly subjects and in those who were positive for anti-Nucleocapside IgG at T12. Remarkably, one third of T12 sera from anti-Nucleocapside IgG negative older individuals were unable to neutralize the BA.5 variant strain. Finally, the evaluation of T-cell mediated immunity showed that most analysed subjects, independently from age and comorbidity, displayed Spike-specific responses with a high degree of polyfunctionality, especially in the CD8 compartment. In conclusion, vaccinated subjects had high levels of circulating antibodies against SARS-CoV-2 Spike protein 12 months after the primary vaccination, which increased as compared to T6. The enhancing effect could be attributable to the administration of a third vaccine dose but also to the occurrence of breakthrough infection. Older individuals, especially those who were anti-Nucleocapside IgG negative, displayed an impaired capacity to neutralize the BA.5 variant strain. Spike specific T-cell responses, able to sustain immunity and maintain the ability to fight the infection, were present in most of older and younger subjects assayed at T12.

Unexpected vaginal bleeding and COVID-19 vaccination in nonmenstruating women

The association between coronavirus disease 2019 (COVID-19) vaccination and vaginal bleeding among nonmenstruating women is not well studied. The Norwegian Institute of Public Health followed several cohorts throughout the pandemic and early performed a systematic data collection of self-reported unexpected vaginal bleeding in nonmenstruating women. Among 7725 postmenopausal women, 7148 perimenopausal women, and 7052 premenopausal women, 3.3, 14.1, and 13.1% experienced unexpected vaginal bleeding during a period of 8 to 9 months, respectively. In postmenopausal women, the risk of unexpected vaginal bleeding (i.e., postmenopausal bleeding) in the 4 weeks after COVID-19 vaccination was increased two- to threefold, compared to a prevaccination period. The corresponding risk of unexpected vaginal bleeding after vaccination was increased three- to fivefold in both nonmenstruating peri- and premenopausal women. In the premenopausal women, Spikevax was associated with at 32% increased risk as compared to Comirnaty. Our results must be confirmed in future studies.

Five doses of the mRNA vaccination potentially suppress ancestral-strain stimulated SARS-CoV2-specific cellular immunity: a cohort study from the Fukushima vaccination community survey, Japan

The bivalent mRNA vaccine is recommended to address coronavirus disease variants, with additional doses suggested for high-risk groups. However, the effectiveness, optimal frequency, and number of doses remain uncertain. In this study, we examined the long-term cellular and humoral immune responses following the fifth administration of the mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in patients undergoing hemodialysis. To our knowledge, this is the first study to monitor long-term data on humoral and cellular immunity dynamics in high-risk populations after five doses of mRNA vaccination, including the bivalent mRNA vaccine. Whereas most patients maintained humoral immunity throughout the observation period, we observed reduced cellular immune reactivity as measured by the ancestral-strain-stimulated ELISpot assay in a subset of patients. Half of the individuals (50%; 14/28) maintained cellular immunity three months after the fifth dose, despite acquiring humoral immunity. The absence of a relationship between positive controls and T-Spot reactivity suggests that these immune alterations were specific to SARS-CoV-2. In multivariable analysis, participants aged ≥70 years showed a marginally significant lower likelihood of having reactive results. Notably, among the 14 individuals who received heterologous vaccines, 13 successfully acquired cellular immunity, supporting the effectiveness of this administration strategy. These findings provide valuable insights for future vaccination strategies in vulnerable populations. However, further research is needed to evaluate the involvement of immune tolerance and exhaustion through repeated vaccination to optimize immunization strategies.