False posts about HMPV and Covid 'cross-mutation' spark fear online

"Urgent .. India has declared a state of emergency to monitor all Chinese people as cases of HMPV that cross-mutated with Covid-19 are spreading heavily in various cities, including Hong Kong," read a Thai-language Facebook post on January 5, 2025.

The post, shared more than 30,000 times, added the mutated virus causes more severe pneumonia.

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Screenshot of the false post, taken on January 7, 2025

Similar posts were also shared here and here with comments indicating people believed the claims.

"Horrific! How much precaution do we need to survive in this world?" said one. Another commented: "If it's spreading in India and China, that's game over."

HMPV stands for "human metapneumovirus" and generally causes a mild infection of the upper respiratory tract. It has been circulating for decades and people around the world already have some protection against it (archived link).

In contrast, the SARS-CoV-2 coronavirus that causes Covid-19 was unknown when it first emerged in humans in late 2019. That meant people had never been exposed to it and had no immunity, raising the risk of severe illness.

'Simply cannot merge'

A cross-mutation between HMPV and Covid-19 is biologically unlikely, multiple virologists told AFP, contradicting the false posts.

"HMPV and SARS-CoV-2 are two different viruses that evolve independently," Dongyan Jin, a professor of virology from The University of Hong Kong told AFP on January 14, 2025.

"They are from different virus families with very different biology," Siddharth Sridhar, a clinical virologist from the same university separately said on the same day. "They simply cannot merge and become new virus."

He added majority of HMPV infections are "mild" with individuals being able to recover at home. "Like Covid, some groups like elderly can develop more severe disease."

Kamol Suwannakarn, an assistant professor with the Department of Microbiology at Thailand's Mahidol University, also dismissed the online rumours.

"If HMPV cross-mutates with SARS-CoV-2, it may cause the virus to lose its own viral proteins, thus the virus will not be able to survive or reproduce," he said on January 14.

AFP has previously debunked false rumours about a health crisis in China over HMPV cases.

"China's reported levels of acute respiratory infections, including HMPV, are within the expected range for the winter season with no unusual outbreak patterns reported," the World Health Organization noted in a report on January 7, 2025 (archived link).

The Chinese Center for Disease Control and Prevention's sentinel surveillance report from January 16, 2025 showed multiple viruses circulating in the country, including influenza, HMPV, adenovirus and Mycoplasma pneumonia (archived link).

There were also no official reports that India declared a state of emergency over HMPV cases as of January 21, 2024.

In a message posted on Facebook on January 6, India's Health Minister JP Nadda said authorities are closely watching HMPV cases in China (archived link).

"There is no reason to worry," he said. "The virus spreads more during winter and the early spring months."