Nothing alarming: on China’s HMPV cases

Reports of many HMPV cases in China is reflection of heightened surveillance 

Five years after the SARS-CoV-2 virus overwhelmed hospitals in Wuhan, China, acute respiratory diseases caused by viruses including the human metapneumovirus (HMPV) in children and the elderly, and influenza and respiratory syncytial virus (RSV), are increasing in the country, especially in its northern provinces. However, the sharp rise in acute respiratory diseases is not unusual during this time of the year, and as per a Chinese official, the overall number of cases in 2024 would be “smaller” than in 2023. Surprisingly, while the World Health Organization and the U.S. Centers for Disease Control and Prevention have not raised a red flag so far and there is almost nil reporting in the international media, the Indian media is awash with reports of an HMPV “outbreak” in China. A recent meeting of the Joint Monitoring Group under the aegis of the Union Health Ministry noted that the situation in China is “not unusual in view of the ongoing flu season”, and the “usual pathogens that are expected during the season” are causing the present surge in respiratory diseases. The HMPV virus was first identified in children in 2001 in the Netherlands. Infection with HMPV usually occurs by the age of five years with reinfection occurring throughout life as immune protection induced by the virus is too weak to prevent repeated infections. The virus causes upper and/or lower respiratory tract infections, with lower respiratory tract infections being among the most common. While the virus often causes only mild disease, it can lead to severe illness requiring hospitalisation in children, immunocompromised populations and the elderly.

Globally, 3%-10% of hospital admissions and 1% of acute lower respiratory infection-related deaths in children under age five in 2018 are attributed to HMPV, as per a 2021 paper. The study also found that children younger than six months, especially those in low- and lower-middle-income countries, are at greater risk of death caused by the HMPV virus. Detection of a large number of HMPV cases among children aged less than 14 years in China is a reflection of the heightened surveillance and testing for the virus. On the contrary, India does not have any approved inexpensive tests that are widely available for diagnosing the virus. When testing for HMPV in patients with acute respiratory disease should be routine, as the virus has been in circulation for years globally, including India, and fatality is 1% in young children, India is only now expanding the number of laboratories testing for HMPV beyond the Indian Council of Medical Research (ICMR) network due to the spike in HMPV cases in China. What is also urgently needed is a regulatory framework that facilitates a rapid approval of diagnostic tests in the context of local and global outbreaks of novel and less known pathogens.