Sex differences in antibody responses to the 23-valent pneumococcal polysaccharide vaccination

Sex-based difference in immune responses and efficacy of the pneumococcal conjugate vaccine

Vaccine-mediated protection and susceptibility to Streptococcus pneumoniae (pneumococcus) infections are influenced by biological sex. The incidence of invasive pneumococcal disease remains higher in males compared to females even after the introduction of the pneumococcal conjugate vaccine (PCV). However, sex-based differences in the immune response to this conjugate vaccine remain unexplored. To investigate those differences, we vaccinated adult male and female mice with PCV and assessed cellular and humoral immune responses. Compared to females, male mice displayed lower levels of T follicular helper cells, germinal center B cells and plasmablasts, which are all required for antibody production following vaccination. This was linked to lower IgG and IgM levels against pneumococci and lower isotype switching to IgG3 in vaccinated males. Due to lower antibody levels, sera of vaccinated male mice had lower efficacy in several anti-pneumococcal functions including neutralization of bacterial binding to pulmonary epithelial cells as well as direct cytotoxicity against S. pneumoniae. Importantly, while the vaccine was highly protective in females, vaccinated males succumbed to infection more readily and were more susceptible to both lung-localized infection and systemic spread following S. pneumoniae challenge. These findings identify sex-based differences in immune responses to PCV that can inform future vaccine strategies.

Persistence of antibody to 23-valent pneumococcal polysaccharide vaccine: a 5-year prospective follow-up cohort study

BACKGROUND

Pneumococcal vaccines are effective in preventing pneumococcal diseases in adults. The evaluation of the antibodies persistence to the 23-valent pneumococcal polysaccharide vaccine (PPV23) could provide evidence on PPV23 revaccination.

RESEARCH DESIGN AND METHODS

Adults aged ≥ 60 years were selected and vaccinated with PPV23 in Shanghai, and followed up for 5 years with blood samples collection of a 1-year interval. The geometric mean concentrations (GMC) of the IgG against 23 pneumococcal serotypes covered by PPV23 were detected using enzyme-linked immunosorbent assay. The antibodies to 23 pneumococcal serotypes among different groups was analyzed using statistical analysis.

RESULTS

Overall, 517 participants completed all six visits over a 5-year period (2013-2018). The GMC of 23 serotypes in adults aged ≥ 60 years decreased slowly after PPV23 vaccination compared to baseline pre-vaccination (P < 0.05), except serotype 3. Additionally, the multiplicative increase in the antibody concentration after PPV23 vaccination was greater, and the antibody levels of serotypes 1 and 6B were significantly higher at visit 5 than at visit 4 (P < 0.05).

CONCLUSIONS

The pneumococcal antibodies in elderly after PPV23 vaccination could sustain high levels over long-term follow-up, which suggested that the interval of revaccination with PPV23 in elderly should be at least 5 years after the first vaccination.

Sex and gender differences in community-acquired pneumonia

Awareness of the influence of sex ands gender on the natural history of several diseases is increasing. Community-acquired pneumonia (CAP) is the most common acute respiratory disease, and it is associated with both morbidity and mortality across all age groups. Although a role for sex- and gender-based differences in the development and associated complications of CAP has been postulated, there is currently high uncertainty on the actual contribution of these factors in the epidemiology and clinical course of CAP. More evidence has been produced on the topic during the last decades, and sex- and gender-based differences have also been extensively studied in COVID-19 patients since the beginning of the SARS-CoV-2 pandemic. This review aims to provide an extensive outlook of the role of sex and gender in the epidemiology, pathogenesis, treatment, and outcomes of patients with CAP, and on the future research scenarios, with also a specific focus on COVID-19.

Pneumococcal IgG Antibody Responses to 23vPPV in Healthy Controls Using an Automated ELISA

Measurement of pre- and post-pneumococcal antibody levels after immunization with the 23-valent capsular polysaccharide pneumococcal vaccine (23vPPV) is indicative of a T-independent antibody response. The World Health Organisation ELISA is considered gold standard yet is labor-intensive and technically difficult to perform. Interpretation criteria defining an adequate response to 23vPPV remain controversial. The diagnostic Immunology Laboratory at The Royal Children's Hospital, Melbourne (RCH), performs an in-house multi-serotype automated ELISA. The primary objective of this study was to verify RCH interpretation criteria for the laboratory's automated ELISA. Forty pneumococcal conjugate vaccine (PCV)-naïve healthy adults aged 18 to 25 years and 22 PCV-primed healthy children aged 2 to 5 years were immunized with 23vPPV. A serum sample was collected immediately prior and 28 to 42 (± 7) days post immunization. Samples were analyzed on the Tecan Freedom Evo 200 ELISA with adequate response defined as post-immunization antibody level of 1.3 µg/mL or fourfold rise from baseline in ≥ 10/15 serotypes in adult participants and ≥ 4/8 serotypes in pediatric participants. Thirty-nine (97.5%) adults and 22 (100%) children achieved an adequate response to 23vPPV. In PCV-naïve adults, serotypes contained within the conjugate vaccines were less immunogenic, with 12 (30%) adults not achieving an adequate antibody response when only PCV serotypes were used for interpretation. Our diagnostic laboratory has verified the interpretation criteria used for an automated multi-serotype pneumococcal ELISA method. Clinical Trial Registration: ANZCTR registration number ACTRN12618000822280.