Post-marketing surveillance of 10,392 herpes zoster vaccines doses in Australia.

BACKGROUND: Immunisation against herpes zoster is recommended for adults aged ≥ 50 years. Two vaccines, a live attenuated (ZVL, Zostavax®) and an adjuvant recombinant subunit (HZ/su, Shingrix®), are available in Australia. Immunisation guidelines are shifting their recommendations towards HZ/su because of higher efficacy in preventing herpes zoster and associated complications. However, there are limited post-marketing data comparing the safety profiles of these vaccines. METHODS: Data from SmartVax, an active surveillance system for monitoring adverse events following immunisation (AEFIs) utilised by > 450 clinics throughout Australia, were analysed. Data from patients aged ≥ 50 years, who received ZVL or HZ/su, from 1 June 2021 to 31 May 2022, at clinics that utilised SmartVax were included. The proportion of records where patients who reported any, local, and systemic AEFIs after receiving ZVL or HZ/su were compared using multivariable logistic regression models. RESULTS: Data from 10,392 immunisation records (n = 8341 ZVL; n = 2051 HZ/su) were included. The proportion of AEFIs reported was higher with HZ/su (41.9 % [any], 33.8 % [local], 25.2 % [systemic]) than with ZVL (8.7 % [any], 6.2 % [local], 3.5 % [systemic]). After controlling for demographic variables, HZ/su presented a 6-fold increase in the odds (OR 6.44; 95 %CI: 5.57-7.46) of a reported AEFI compared to ZVL. Only 59 (0.6 %) of vaccinations lead to medical attention being sought due to an AEFI. CONCLUSIONS: While rates of AEFIs was higher with HZ/su than ZVL, most AEFIs were mild and did not require medical attention. Our findings support the change in vaccine recommendations and the use of HZ/su in immunisation programs.

Robust immunity to influenza vaccination in haematopoietic stem cell transplant recipients following reconstitution of humoral and adaptive immunity.

Objectives: Influenza causes significant morbidity and mortality, especially in high-risk populations. Although current vaccination regimens are the best method to combat annual influenza disease, vaccine efficacy can be low in high-risk groups, such as haematopoietic stem cell transplant (HSCT) recipients. Methods: We comprehensively assessed humoral immunity, antibody landscapes, systems serology and influenza-specific B-cell responses, together with their phenotypes and isotypes, to the inactivated influenza vaccine (IIV) in HSCT recipients in comparison to healthy controls. Results: Inactivated influenza vaccine significantly increased haemagglutination inhibition (HAI) titres in HSCT recipients, similar to healthy controls. Systems serology revealed increased IgG1 and IgG3 antibody levels towards the haemagglutinin (HA) head, but not to neuraminidase, nucleoprotein or HA stem. IIV also increased frequencies of total, IgG class-switched and CD21loCD27+ influenza-specific B cells, determined by HA probes and flow cytometry. Strikingly, 40% of HSCT recipients had markedly higher antibody responses towards A/H3N2 vaccine strain than healthy controls and showed cross-reactivity to antigenically drifted A/H3N2 strains by antibody landscape analysis. These superior humoral responses were associated with a greater time interval after HSCT, while multivariant analyses revealed the importance of pre-existing immune memory. Conversely, in HSCT recipients who did not respond to the first dose, the second IIV dose did not greatly improve their humoral response, although 50% of second-dose patients reached a seroprotective HAI titre for at least one of vaccine strains. Conclusions: Our study demonstrates efficient, although time-dependent, immune responses to IIV in HSCT recipients, and provides insights into influenza vaccination strategies targeted to immunocompromised high-risk groups.