Lancet study finds HMPV outbreak in India hit children the hardest

A study that looked into trends of the respiratory infection HMPV that broke out in India early this year has found that children were the most affected, with highest diagnoses among those aged 1-2.

Published in The Lancet Regional Health Southeast Asia journal, the study also found most HMPV-positive cases presented with symptoms similar to those of acute respiratory illness or influenza, with fever and cough being the most common.

However, researchers from Indian Council of Medical Research (ICMR) institutes and the Directorate of Public Health and Preventive Medicine, Government of Tamil Nadu, noted no "recent change in the epidemiological features of HMPV".

The outbreak in India was linked to seasonal one in China triggered in late 2024, attracting significant attention due to an increase in cases and potential impact.

Studies estimate the Human Metapneumovirus (HMPV) was responsible for over six per cent of respiratory illnesses and five per cent of hospitalisations in China.

Cases started to emerge in India during second week of January in states, including Gujarat and Puducherry.

The researchers stressed that strengthening surveillance continues to be critical to understand emerging disease-causing viruses and guiding public health policies.

Data collected during 2019-2023 and in 2024-2025 under the Model for Integrated Influenza Surveillance in Tamil Nadu was analysed.

Diagnostic tests were conducted by labs forming the Virus Research and Diagnostic Laboratory Network, established in 2014 under the Department of Health Research, Ministry of Health and Family Welfare.

Between 2019-2023, over 20,000 were tested for HMPV, of whom 1,030 (3.2 per cent) were positive, and more than 11,100 in 2024, of whom 367 (3.3 per cent) were positive.

The authors said, "Majority of tests were conducted among children."  "The highest positivity was observed in those aged 1-2, with 4.5 per cent (128/2864) testing positive in 2019-2023 and 4.6 per cent (70/1508) in 2024," they wrote.

Further, "fever and cough were the most common symptoms, reported in 70.3 per cent of cases from 2019 to 2023 and 79.6 per cent (292/8398) in 2024, and in 60.5 per cent (401/12,059) and 60.8 per cent (223/5977) of cases, respectively," the team said.

Duration of sickness was found to typically last for 11 days, with a typical hospital stay of seven days.

The researchers said that the higher testing and positives seen in 2024 highlight that HMPV is being increasingly recognised as a significant respiratory pathogen in India.

"Strengthening surveillance networks remains critical to understanding the burden of such emerging viral pathogens and guiding public health policies," they said.