Background and Objectives:
Since 2021, a recombinant adjuvated anti-Herpes Zoster (HZ) vaccine (RZV) is available in Italy, offered to immunocompromised subjects. In pre-marketing evaluation, the most reported adverse reaction following RZV were pain (78%), redness (38%), and swelling (26%). Due to the recent introduction, no real life data about safety profile of RZV are available. This study investigates AEFIs occurring after RZV administration to design its safety profile.

Methods:
This is a cross-sectional observational study. The study population is represented by patients vaccinated with adjuvated anti-HZ vaccine within Bari Policlinico General Hospital, from 01/10/2021 to 31/08/2022. Subjects were contacted via phone call two weeks after the first dose and two weeks after completing the vaccination cycle, and were asked about AEFIs they experienced.

Results:
Three-hundred-eighty-two people were vaccinated and 366 accepted to participate to the follow-up (response rate 95.8%). Two-hundred-five subjects underwent both administrations; 571 doses were therefore administered. The male-to-female ratio was 189/177, with mean age of 58.6 ± 13.7 years. Out of 571 follow-ups, 292 AEFI cases were reported (reporting rate 51.14 per 100 administered doses). One-hundred-ninety-four AEFIs happened after the first dose (53.01 per 100 doses), while 98 occurred after the second (47.80 per 100 doses). Most common symptoms were pain at site of injection (45.2 per 100 doses), asthenia (13.1 per 100 doses), redness at site of injection (9.5 per 100 doses) and fever (9.1 per 100 doses). No serious AEFIs were identified. Three subjects (0.82%) reported HZ after vaccination, of which only one case occurred more than two weeks after immunization, thus representing a vaccine failure. Risk of AEFIs was not influenced by sex, age, or dose number (p>0.05).

Conclusions:
The recombinant adjuvated vaccine’s safety profile appears to be coherent with pre-marketing evidence. Vaccine failure was sporadic, suggesting high effectiveness even in immunocompromised subjects.