A recent study conducted in the Bentiu camp in South Sudan, a site frequently affected by hepatitis E outbreaks, has demonstrated the effectiveness of a two-dose regimen of the Hecolin vaccine in combating the disease during an epidemic. The research, a collaborative effort between Médecins Sans Frontières (MSF) and the Centre for Emerging Viral Diseases, offers crucial insights into vaccine deployment in challenging environments.
The study addressed a critical gap in knowledge regarding the Hecolin vaccine, developed in China and licensed in some countries since 2011. While the WHO has recommended it as a potential tool in outbreaks, its effectiveness in diverse populations and with a reduced dosage schedule (two doses instead of the standard three) remained uncertain. "That's why it was essential to study the vaccine's effectiveness on other populations and in regions where the type of virus circulating is different from China, as well as the logistical feasibility of such a campaign," explained Isabella Eckerle, Professor at the Faculty of Medicine and Director of the UNIGE-HUG Centre for Emerging Viral Diseases.
Study Design and Results
The vaccination campaign targeted individuals aged 16 years and older and was conducted over three rounds in March, April, and October 2022. Researchers then compared the vaccination status of 201 patients who tested positive for hepatitis E between May and December 2022 with that of asymptomatic individuals in their neighborhood. Despite a lower-than-expected number of hepatitis E cases post-vaccination, the study revealed that two doses of the vaccine provided effective protection.
"Our study then compared the vaccination status of 201 patients testing positive for hepatitis E between May and December 2022 with that of others in their neighbourhood presenting no symptoms. Despite fewer hepatitis E cases than expected after vaccination, our study revealed that two doses of vaccine was effective, an excellent result given the particular context of a camp for displaced people," said Iza Ciglenecki, Operational research coordinator at MSF Switzerland.
Implications for Global Health
The findings have significant implications for global health efforts to combat hepatitis E, particularly in regions with poor sanitation and limited resources. The study's confirmation of the vaccine's effectiveness with a two-dose schedule, even during an epidemic, has contributed to the WHO's decision to establish a global stockpile of hepatitis E vaccines for emergency use. This stockpile has the potential to save numerous lives, especially considering the high mortality rate (up to 50%) among pregnant women and individuals with chronic illnesses infected with hepatitis E.
"Our results combined with others helped lead to recent approval by WHO's International Coordinating Group (ICG) on Vaccine Provision of a stockpile of hepatitis E vaccines for emergencies. This stockpile has the potential to save many lives and we're looking forward to seeing it in action. These results have also already contributed to the WHO recommendations on the use of a two-dose schedule", concludes Andrew Azman.
Furthermore, the study's laboratory analyses of viral samples provided valuable insights into virus transmission and the performance of diagnostic tests, which can inform the development of more effective outbreak response strategies in the future. Hepatitis E symptoms are similar to other diseases that cause acute jaundice, making it difficult to detect. Some estimates put the global burden at around 50,000 deaths a year.
