Introduction:
The Expert Committee of Travel Medicine in Switzerland claims that people who have lived in a tropical country (outside of Europe, North America or Australia/New Zealand) for more than 5 years or who are older than 65 years of age will have already developed an immunity against hepatitis A, either through symptomatic or asymptomatic infection in infancy. Therefore, the policy of the Committee is that persons from these two groups are not vaccinated nor is their serology tested before traveling. The current validity of the Committee’s claim is questionable due to the improved hygiene over the years and the decreasing seroprevalence of hepatitis A in countries worldwide. The primary objective of this study is to determine the seroprevalence of anti-HAV in these two groups. This will then provide the basis from which to challenge the claim of the Expert Committee and decide if the recommendation to not vaccinate or serologically test these two groups against Hepatitis A should be changed.
Method:
This is a cross-sectional, monocentric national observational study. Individuals who consulted the travel clinic of Unisanté who were aged 60 or older or had lived in a tropical country for at least 5 years were tested for Anti-HAV antibodies.
Due to the COVID-19 pandemic, the serum samples of only 20 participants were collected, compared to the 200 that were planned. Therefore, further literary research was done to complement the data collected.
Before any data analysis was performed, the following guidelines for action were decided: if a seroprevalence is >90%, then no vaccination or serology test should be taken. If it is between 50% and 90%, then a serology test should be done first before potentially vaccinating. If it is below 50% then the traveler should be vaccinated.
Results:
The participants who met both inclusion criteria all had a positive serology result. No one in the study with a negative test result was over 60 years of age, therefore those with a negative serology had all lived in a tropical country for 5 years or more. The total seroprevalence rate (both groups combined) was 75%. This would indicate that a serology test should be done first before a vaccination that might otherwise be required for people over 60 years old or who have lived in a tropical country for 5 years or more.
Conclusion:
In conclusion, this study would propose changing the Committee’s current recommendation to begin performing serology tests for these two groups of people and vaccinating where appropriate. However, more participants and further study are needed, especially in Switzerland, as the epidemiology of the hepatitis A virus is constantly changing.