IMPACT OF HEPATITIS A VACCINATION IN PRIORITY ADULT GROUPS AS AN OUTBREAK CONTAINMENT STRATEGY IN BRAZIL

Introduction and Objectives

Viral hepatitis A (HAV) is an infection primarily transmitted via the fecal-oral route. In 2016, the World Health Organization observed an increase in HAV cases in low-endemicity countries, associated with oral-anal sexual practices.

To evaluate the outcome of hepatitis A vaccination in adults from priority groups as a strategy for containing the hepatitis A outbreak.

Materials and Methods

A document analysis of state technical reports and technical notes from the Ministry of Health addressing epidemiological outbreaks in two Brazilian capitals was conducted.

Results

In Brazil, there were HAV outbreaks in São Paulo (2017) and Curitiba (2024), with similar characteristics and a predominance of cases in adult males via sexual transmission. In São Paulo, an increase in cases was noted, with 786 reported cases, 80% of which were among individuals aged 18 to 39. In 2018, a reactive vaccination campaign against HAV was initiated, leading to a reduction in cases in subsequent years. In Curitiba, 315 cases were confirmed between 2023 and 2024, with 71.1% of cases in adults aged 20-39. The same strategy was initiated in June 2024, resulting in an 80% reduction in the absolute number of cases by November 2024.

Conclusions

In response to the identified outbreaks, the Ministry of Health developed strategies for adults in priority groups and implemented HAV vaccination for these groups, achieving effective outbreak control. In May 2025, given the positive outcomes, the HAV vaccine was incorporated for all users of HIV Pre-Exposure Prophylaxis (PrEP) as a preventive measure.

Conflict of interest: None