What question did this study set out to answer?

This research examines the immunological effects of delayed hepatitis A virus exposure, focusing on age-related disease severity.

April 13, 2026BMC Infectious DiseasesOpen Access

Immunological consequences of delayed exposure to hepatitis A virus: evidence consistent with CD8+ T-cell–mediated immunopathology

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Why the study?

Does delayed exposure to HAV increase clinical severity and peripheral cellular immune responses in patients with acute HAV infection?

Population

34,118 confirmed or probable HAV cases from statewide surveillance data, and an immunological substudy of…

Comparison

Delayed primary exposure to HAV (≥ 18 years) vs Early primary exposure to HAV (< 18 years)

Design

Cohort

Authors

PMPeter Asaga Mac VKVijeesh Kadukkatti MBMathew K. Brijil

Discussion

Member takes

Implication

Adult primary HAV infection is associated with increased clinical severity and heightened peripheral cellular immune responses, independent of viral load, supporting childhood vaccination in transitioning regions.

Key Points

This research examines the immunological effects of delayed hepatitis A virus exposure, focusing on age-related disease severity.
Analyzed statewide surveillance data from Kerala, India, from 2020 to 2024, encompassing over 34,000 confirmed HAV cases.
Conducted an immunological substudy of 180 patients with acute HAV infection stratified by age of exposure.
Assessed clinical severity, hospitalization, liver biochemistry, peripheral CD8+ T-cell responses, plasma cytokines, and viral load.
Applied multivariable logistic regression to identify factors associated with moderate-to-severe disease.
Adults (≥ 18 years) had significantly higher odds (adjusted odds ratio 8.42) of moderate-to-severe disease compared to those infected earlier.
Moderate-to-severe disease occurred in 69.5% of delayed exposure cases versus 7.7% in early exposure cases.
Delayed exposure correlated with stronger CD8+ T-cell responses and higher plasma IFN-γ and TNF-α levels, along with increased aminotransferase levels and hospitalization rates.
Viral load did not show significant differences between age groups.

Structured PICO

Does delayed exposure to HAV increase clinical severity and peripheral cellular immune responses in patients with acute HAV infection?

Population

34,118 confirmed or probable HAV cases from statewide surveillance data, and an immunological substudy of 180 patients with confirmed acute HAV infection

Intervention

Delayed primary exposure to HAV (≥ 18 years)

Comparator

Early primary exposure to HAV (< 18 years)

Outcome

Moderate-to-severe clinical disease

Cite This Study

Mac et al. (2026) studied this question.

synapsesocial.com/papers/69dc892e3afacbeac03eaf60 https://doi.org/10.1186/s12879-026-13193-x

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