Introduction:

hepatitis A virus infection has a universal distribution. In Uruguay, this disease is mandatory. Before the start of universal vaccination in 2008 (two doses at 15 and 21months), the vaccine was used successfully to control outbreaks and in risk populations. For many years this disease had a high prevalence and fulminant hepatic failure caused by this virus was the leading cause of liver transplantation in the country.

Objectives:

describe the epidemiology and variations of reported cases of Hepatitis A in Uruguay between 1/1/1984 and 12/31/2023.

Methodology:

observational, descriptive, retrospective study. All cases reported to the Ministry of Health (MS) during the period from 1/1/84 to 12/31/23 were included. Data source: National Registry of Notifiable Diseases of the Epidemiology Division of the MS.

Variables: reported cases, average annual incidence, age, outbreaks. Statistical analysis: frequency distribution, summary measures and statistical significance tests (significant p ≤ 0.05). Several periods were established: 1984 to 2004 (pre-vaccine I, Pre. I); 2005 to 2007 (pre-vaccine II, Pre. II); 2008 (start of universal vaccination, IVU); 2009 to 2016 (post-vaccine I, Postv. I); and 2017 to 2023 (post-vaccine II, Postv.

II).

Results:

pre. I: average annual cases: 1,647, incidence rate 50/100,000 inhabitants (95% CI 48 - 53). Pre. II: average annual cases: 1,724, rate 53/100,000 (95% CI 50 - 55). During this period, the vaccine was used as outbreak control and vaccination strategy in populations at risk. In 2008 (IVU), the average annual number of cases was 340, with an incidence rate of 10.2 per 100,000 (95% CI 9.1 - 11.2). Postv. I: average annual cases 62, incidence rate 1.6/100,000 (95% CI 1.1 - 2). Postv. II: average annual cases 7.1; rate 0.21/100,000 (95% CI 0.1 - 0.3). Since 2010, no outbreaks have been reported in neighborhoods or cities. Since 2007, there have been no liver transplants for acute liver failure or deaths from hepatitis A.

Conclusions:

the incidence rate of hepatitis A decreased almost 50-fold from the years prior to the vaccine mainly from universally vaccinating children, which demonstrates the collective protection of the vaccine. The use of vaccination as an outbreak control strategy was useful before the start of universal vaccination. Currently, hepatitis A cases occur in unvaccinated adults.

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