According to the Centers for Disease Control and Prevention (CDC), hepatitis E (HEV) is more common in many parts of the world where sanitation is poor and people have limited access to clean drinking water.1 It is more rare in the US, but it is a leading cause of acute viral hepatitis, particularly in Asia and Africa.2 HEV is especially dangerous for pregnant women and people with chronic illnesses, with a mortality rate of up to 10-50 %.3
‘Symptoms of hepatitis E are similar to other diseases that cause acute jaundice, making it difficult to detect,” Andrew Azman, PhD, epidemiologist, UNIGE-HUG Centre for Emerging Viral Diseases, Médecins Sans Frontières [Doctors Without Borders], and Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, said in a statement. “While we don’t have precise estimates of the global burden, some have put it at around 50,000 deaths a year.”3
Azman led a study examining the Hecolin HEV vaccine in staving off an outbreak in the Bentiu refugee camp came in South Sudan back in 2022.
“The Bentiu camp in South Sudan, home to more than 100,000 people who have been displaced due to civil war, is a regular victim of hepatitis E and other waterborne disease outbreaks, likely due to the poor sanitation conditions and frequent flooding,” he said.3
Azman and a team of investigators utilized the vaccine, developed in China. The study's results were published in The Lancet Infectious Diseases.
The investigators identified 859 patients with suspected HEV. Of this group, 201 met the eligibility criteria and 21 cases had laboratory confirmed hepatitis E. Among the confirmed cases, 10 (48%) were unvaccinated compared with 33 (27%) of 121 matched controls, between May 10 and Dec 30, 2022.2
What You Need to Know
Hepatitis E is a significant cause of acute viral hepatitis, especially in regions with poor sanitation and limited access to clean drinking water. It poses severe risks to pregnant women and people with chronic illnesses, with mortality rates reaching 10–50%. Globally, it is estimated to cause around 50,000 deaths annually.
The study in South Sudan's Bentiu refugee camp demonstrated that the Hecolin hepatitis E vaccine, administered in two doses, showed moderate to high efficacy. The adjusted two-dose vaccine effectiveness was estimated at 89.4%, confirming its protective capability during outbreaks.
The findings of the study influenced the WHO to approve a stockpile of hepatitis E vaccines for emergency use and revise recommendations to include a two-dose schedule.
The vaccine showed high efficacy.
“In the primary analysis we estimated an unadjusted two-dose vaccine effectiveness of 67·8% (95% CI –28·6 to 91·9), and a 2-dose vaccine effectiveness of 840% (–2085 to 992) after adjustment for potential confounders,” the investigators wrote. “The bias indicator analysis suggested that test-negative cases might have been more likely to have been vaccinated than their matched community controls due to different health-care seeking behaviors, potentially meaning underestimation of effectiveness estimates. The test-negative design, which uses facility-matched controls, led to an adjusted two-dose effectiveness of 89·4% (564 to 98.0).”2
The vaccine has previously been recommended by the WHO as a potential prophylaxis strategy. Until this South Sudan outbreak, it had only been utilized in controlled clinical trials and travel medicine in China.3
‘‘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,’’ Isabella Eckerle, Professor at the Faculty of Medicine and Director of the UNIGE-HUG Centre for Emerging Viral Diseases said in a statement. ‘‘In particular, it was important to understand its effectiveness after just 2 doses, whereas it is usually administered in three doses 6 months apart.’’3
The study confirmed the protection provided by 2 doses during an epidemic, and the reduction of the disease. ‘‘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,” Azman said. “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 2-dose schedule.”3
References
1.Hepatitis E Basics.CDC. May 14, 2024. Accessed Janaury 27, 2025. https://www.cdc.gov/hepatitis-e/about/index.html
2. Nesbitt RC, Kinya Asilaza V, Alvarez C, et al. The effectiveness of two doses of recombinant hepatitis E vaccine in response to an outbreak in Bentiu, South Sudan: a case-control and bias indicator study. Lancet Infect Dis. Published online January 8, 2025. doi:10.1016/S1473-3099(24)00657-1
3.Hepatitis E vaccination is effective in an epidemic. Eurkealert. January 14, 2025. Accessed January 27, 2025.
https://www.eurekalert.org/news-releases/1070407
