Studies from major Indian cities show hepatitis A accounts for 21.4% to 65.9% of acute liver failure cases.
Published Sep 30, 2025 | 7:00 AM ⚊ Updated Sep 30, 2025 | 7:00 AM
Synopsis: A national study by ICMR reveals Kerala’s low hepatitis A seroprevalence (44.8%) compared to South India’s intermediate rates (74.8%-83.1%). Improved sanitation reduces early exposure, increasing adult susceptibility to severe infections. The study highlights India’s epidemiological transition, urging state-specific vaccination policies. Kerala’s low endemicity necessitates outbreak preparedness, while cost-effective vaccination could address rising acute liver failure cases.
A national study has revealed striking differences in hepatitis A exposure across South Indian states, with Kerala standing out as having dramatically lower infection rates compared to its neighbours, according to research published in The Lancet by the Indian Council of Medical Research (ICMR).
The comprehensive study, which analysed blood samples from 14,778 individuals aged 6-30 years across India, found that while the national average shows 90 percent of young Indians have been exposed to hepatitis A virus (HAV), South Indian states present a complex picture that mirrors the country’s broader epidemiological transition.
Kerala, often hailed as India’s most developed state in terms of human development indicators, recorded the lowest hepatitis A seroprevalence nationally at just 44.8 percent – less than half the national average. This finding places the state in the “low endemicity” category, a classification shared only with West Bengal among the 21 states studied.
“The state of Kerala has the highest human development index (HDI) score (0.775) in India and the highest proportion of households with access to a toilet facility in the country. Sustained investments in public health, sanitation, education, and healthcare access may have contributed to lower early-life HAV exposure,” the study authors noted.
However, this achievement comes with an unexpected health risk. The low exposure rates mean a large portion of Kerala’s population remains susceptible to hepatitis A infection, particularly adults who could develop severe symptoms if infected later in life.
The concern is not theoretical. Kerala has already experienced outbreaks where young adults, rather than children, were the worst affected. During a 2016 village outbreak, researchers found that of 27 children under nine years tested for hepatitis A antibodies, only three were positive, demonstrating the state’s extremely low childhood exposure rates.
Hepatitis A is a viral infection that primarily affects the liver, spreading through the fecal-oral route via contaminated food, water, or direct contact with infected individuals. Unlike its more dangerous cousins Hepatitis B and C, HAV does not cause chronic disease but can lead to severe acute illness, particularly dangerous for teenagers and adults.
The virus presents a paradox in public health: in areas with poor sanitation, children typically contract the infection early in life, often asymptomatically, and develop lifelong immunity. However, as living conditions improve and exposure is delayed to later ages, the disease becomes more severe and potentially life-threatening.
The clinical implications are significant. While young children who contract hepatitis A often show no symptoms or mild flu-like illness, adults can experience weeks of debilitating symptoms including severe fatigue, nausea, abdominal pain, and jaundice. In severe cases, particularly among adults, the infection can progress to acute liver failure, requiring hospitalization and potentially liver transplantation.
In stark contrast to Kerala, the other South Indian states – Karnataka, Andhra Pradesh, Tamil Nadu, and Telangana – all fall into the “intermediate endemicity” category, though with varying prevalence rates.
Karnataka leads among South Indian states with 83.1 percent overall seroprevalence, showing a typical age-related progression from 53.5 percent in children aged 6-10 years to 96.8 percent in those aged 16-30 years. Andhra Pradesh follows with 76.7 percent overall prevalence, while Tamil Nadu and Telangana record similar rates at 75.1 percent and 74.8 percent respectively.
“Age-specific seroprevalence curves indicate increasing seroprevalence with age,” the researchers observed, noting that this pattern is consistent across most Indian states but varies significantly in magnitude.
The study’s findings paint a picture of India in epidemiological transition. Nationally, the research found that 74.7 percent of children aged 6-10 years had been exposed to hepatitis A, rising to 85.2 percent among those aged 11-15 years, and reaching 96.9 percent in the 16-30 age group.
“Based on the WHO criteria, India was classified as having an intermediate endemicity level for HAV infection,” the authors stated, marking a significant shift from previous decades when the country would have been classified as high endemicity.
This transition reflects improving sanitation and living conditions across parts of India, but creates new public health challenges. In the 1980s and 1990s, almost all Indian children were infected before age 10, developing lifelong immunity with minimal symptoms. Now, with delayed exposure, teenagers and adults face greater risk of severe illness.
The contrast is stark when comparing states like Kerala with Uttar Pradesh, which recorded the highest seroprevalence nationally at 97.0 percent – the only state classified as “high endemicity.” In Uttar Pradesh, even young children aged 6-10 years showed 91 percent exposure rates, reflecting ongoing transmission due to poor sanitation infrastructure.
The study’s findings have significant implications for India’s vaccination policy debates. Currently, hepatitis A vaccine is available only in the private sector, making it expensive and inaccessible to most families. The World Health Organization recommends considering hepatitis A vaccination introduction based on specific criteria, all of which India appears to meet.
“WHO recommends considering the introduction of hepatitis A vaccination for individuals aged 12 months or older based on the following criteria: transition from high to intermediate endemic level; an increasing trend of acute hepatitis, including severe disease among older children, adolescents or adults; and evidence of cost-effectiveness,” the researchers noted.
The health burden is substantial. Globally, the 2021 Global Burden of Disease Study estimated 160 million HAV infections and nearly 27,000 deaths, with India accounting for one-fifth of global infections and nearly half of the deaths.
Studies from major Indian cities show hepatitis A accounts for 21.4 percent to 65.9 percent of acute liver failure cases, highlighting the severity of the disease burden.
“All the studies highlighted that HAV as one of the commonest causes of acute liver failure in both children and adults,” the researchers emphasised.
The economic argument for vaccination appears strong, particularly for states like Kerala. A recent study conducted specifically in Kerala found that hepatitis A vaccination was cost-saving for both one-year-old infant and 15-year-old teens, regardless of whether serological screening was used prior to vaccination.
“A systematic review of 43 economic evaluation studies on the HAV vaccination, including 15 from middle-income countries, found that universal childhood vaccination without screening was cost-effective,” the study noted, though it highlighted a lack of India-specific cost-effectiveness data.
For South Indian states, the economic calculus varies significantly. While Kerala’s low exposure rates make vaccination highly cost-effective due to the large susceptible population, states like Karnataka with higher natural immunity rates would need different strategic approaches.
The study’s findings suggest India needs a nuanced, state-specific approach to hepatitis A control.
“There is a need for research to address this gap by generating evidence on the burden of symptomatic and severe HAV disease at the national level through existing surveillance systems and hospital-based data sources,” the authors recommended.
For South Indian states, the data suggests different strategies may be needed. Kerala’s low endemicity pattern indicates urgent need for outbreak preparedness and potentially targeted vaccination programs, while other South Indian states with intermediate patterns might benefit from universal childhood vaccination programs.
The research also highlights the need for continued surveillance as India’s epidemiological transition continues.
“Future studies could include testing for both IgG and IgM antibodies to have a more comprehensive understanding of HAV epidemiology, particularly in the 6 to 10-year age group,” the researchers suggested.
As India grapples with whether to include hepatitis A vaccine in its Universal Immunization Programme, this study provides crucial evidence for policy makers. The stark differences between states like Kerala and others underscore the need for flexible, evidence-based approaches that account for regional variations in disease patterns and population susceptibility.
“In conclusion, our study findings indicate an intermediate level of endemicity for HAV infection in India,” the authors stated.
“While this supports consideration of hepatitis-A vaccination, further data on disease burden and cost-effectiveness are needed to guide evidence-based policy decisions.”
(Edited by Amit Vasudev)
