Hepatitis E Vaccine Demonstrates High Efficacy in Outbreak Setting
The Hecolin hepatitis E virus (HEV) vaccine was delivered with a reduced 2-dose schedule to people living in a refugee camp to try to reduce an outbreak.
Andrew Azman, PhD
Image credit: Johns Hopkins Bloomberg School of Public Health
During a hepatitis E outbreak in 2022 in South Sudan at the Bentiu refugee camp, the Hecolin HEV vaccine was shown to be highly protective. The results were published in The Lancet Infectious Diseases.
“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 84.0% (–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).”1s
The camp was an environment that enabled outbreak conditions. “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,” study senior author 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.
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, 2022.1
Along with its protection, 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,”2
About the Vaccine
Developed in China, the Hecolin vaccine was approved in the country in 2011. It is a recombinant protein-subunit hepatitis E vaccine (HEV239) developed by Xiamen Innovax Biotech Co. It is recommended for adults aged 16 and older, particularly those at high risk of HEV infection. The World Health Organization (WHO) has recommended using the Hecolin vaccine in disease outbreak settings.
HEV’s Impact
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 Approximately 20 million people worldwide are infected annually with HEV, according to the WHO. The virus is especially dangerous for pregnant women and people with chronic illnesses, with a mortality rate of up to 10%-50%.3
