A few recent headlines have suggested something novel and infectious might be brewing among China’s children. But is it really novel? The hard-to-source headlines imply that we should be concerned. But there’s nothing to indicate anything abnormal. So far, it looks like the normal endemic seasonal nasties doing what they do. “Chinese flu?” is more like “Media ballyhoo”.

What’s the news?

In the past week, there has been a lot of mainstream and social media noise suggesting a mysterious respiratory illness sweeping China’s children, filling hospitals and crematoria. This has been driven by a seldom-discussed Human metapneumovirus (HMPV). Let’s dig deeper.

What is HMPV?

HPMV is not a new or emerging virus. It’s about 200 years old and has been detected in samples from 60 years ago. HMPV is a globally distributed endemic RNA virus that we know causes asymptomatic, mild, moderate and severe infections every year.

HMPV exists in two major types (A and B) within which genotypes can be identified (A1, A2a, A2b, A2c, B1 and B2). As it’s an RNA virus, it keeps evolving, with the most likely variants to spread being the ones that compete best to infect us.

It can cause death and has been known to cause outbreaks in aged care facilities, as well as being a pathogen most children acquire by two years of age. This pattern of early acquisition is similar to most respiratory viruses.

Yes, there actually are more endemic viral and bacterial nasties than influenza virus, respiratory syncytial virus (RSV) and SARS-CoV-2. And we all share in them, wherever you may be reading this.

The story

Some of the earliest stories (apologies if I’ve missed an earlier one) appear in The Star, [3] Newsweek [4] and the Hindustan Times.[5] The original data is said to have come from a World Health Organization (WHO) bulletin (according to [5]), but I have yet to find that.

The stories have been interpreted and amplified on Facebook, NDTV and many other sites. Some sites have quoted social media posts but usually don’t have any sources. Then, the comments go to work to inflame and create more anxiety. And there is inflammatory and scary language in the headlines to draw you in. The usual stuff.

Does this all sound familiar?

It should. In 2023, there was a very similar spray of stories – see an example headline below. The WHO reported that China identified the surge was due to known viruses and bacteria, including influenza virus, Mycoplasma pneumoniae (a bacterial infection typically affecting children), respiratory syncytial virus (RSV), and SARS-CoV-2.[7] In other words, while the totals may be a bit different post-pandemic, the makeup of the infections was not new.

Every time the weather turns colder (although that varies with climate [15]), a soup of viruses and some bacteria emerge, and just because you don’t get really sick this year doesn’t mean others don’t. It also doesn’t mean you weren’t infected – we have immune systems that can quickly shut down infections before you can get ill. Or it can turn an infection into a one-day sniffle.

What ties 2023 to 2024 together? Timing. This is occurring in winter, which is traditionally a time filled with lots of different respiratory viruses.

Fallout

These stories have, in turn, raised questions in other countries; for example, in Australia, our Minister for Health and Aged Care, The Hon. Mark Butler MP, was asked by reporters if the Government was doing anything about the illness surge in China – he gave a great answer, by the way (well-briefed)! [2]

But let’s remember that SARS-CoV-2 also emerged during a busy winter virus-filled background, so this event is not to be sneezed at unless there was a bit more to the story.

A bit more to the story

HMPV is sought in laboratories as part of respiratory virus testing panels in larger laboratories worldwide. Whether China routinely tests for HMPV in its hospital laboratories is unclear. The Chinese Center for Disease Control and Prevention (CCDC) has a fact sheet on this virus.[6] Also, Chinese researchers certainly know the tools to use to test as they have published extensively on HMPV.[8-14]

In May 2023, the CCDC published a report on HMPV RT-PCR detections in Henan Province, which spanned 2017 to 2023.[14] It clearly showed that HMPV is no stranger to this part of the world and can, at times, cause epidemics during which 30% to 40% of the samples being tested are positive for HMPV. For most of those years, one subtype dominated, HMPV-A, but both were found, as were most of the genotypes.

Wrap up

What do we know then, and should we be as concerned as those headlines try to make us?

China is aware of HMPV and can test for it, although it’s not clear they do that routinely at a national level. We know China has had a busy season of childhood and adult respiratory illness in the colder months of 2023 as well. Nothing surprising arose from that.

This year, the detection of influenza virus is a little lower than last year, but the occurrence of pneumonia is a little higher.[18] Officials mentioned influenza, rhinoviruses, HMPV, and Mycoplasma pneumonia were part of the mix this year, as they were in 2023, along with adenoviruses.[22,23,25]

Below, you can see a graph from the Chinese National Influenza Center (CNIC) report for the final week of 2024. Flu was rising in the south and already high in the north but slowing. China has an excellent influenza laboratory testing and characterisation network, by the way. Chinese authorities have also stated that this is a normal burden of disease, driven mainly by viruses (unspecified) and Mycoplasma pneumoniae.[18] Furthermore, the CCDC is now creating an expanded surveillance system for pneumonia and monitoring more already known pathogens using sentinel surveillance hospitals.[17]

Interestingly, HMPV cases have been peaking during our spring and summer here in Queensland, based on one large private pathology laboratory’s public PCR-based testing data.[24] Similar to the spring and summer of 2023. Usually, HMPV is a colder-months virus (occurring on either side of the flu peak), so it looks like we are still shaking off the impact of pandemic measures plus experiencing the effects of living with a new respiratory virus (SARS-CoV-2) that peaks twice a year and may interact with the epidemics of other viruses like HMPV.

After all that, I don’t see any signal to suggest any new virus – or any stupidly named “Chinese flu” – emerging based on the information on hand. But we haven’t returned to the old pre-pandemic respiratory virus seasonal timings. Time will tell as to whether we ever do.

References

1. https://edition.cnn.com/2023/11/24/china/china-beijing-hospitals-surge-illnesses-children-intl-hnk/index.html
2. https://www.health.gov.au/ministers/the-hon-mark-butler-mp/media/minister-for-health-and-aged-care-press-conference-5-january-2025?language=en
3. https://www.thestar.com.my/aseanplus/aseanplus-news/2024/12/31/cambodia-issues-health-alert-on-hmpv-outbreak-in-china-similar-to-flu-covid-19
4. https://www.newsweek.com/human-metapneumovirus-hmpv-china-outbreak-explainer-2009126
5. https://www.hindustantimes.com/world-news/china-battles-new-mystery-virus-outbreak-five-years-after-covid-pandemic-101735892326018.html
6. https://en.chinacdc.cn/health_topics/infectious_diseases/202307/t20230719_267896.html
7. https://www.who.int/news/item/22-11-2023-who-statement-on-reported-clusters-of-respiratory-illness-in-children-in-northern-china
8. https://www.nature.com/articles/s41598-019-50340-8
9. https://onlinelibrary.wiley.com/doi/10.1111/irv.12535
10. https://www.sciencedirect.com/science/article/pii/S0163445311005305
11. https://onlinelibrary.wiley.com/doi/10.1002/jmv.24411
12. https://wwwnc.cdc.gov/eid/article/9/6/03-0009_article
13. https://journals.asm.org/doi/10.1128/jcm.00809-12
14. https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2024.087
15. https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(24)00090-1/fulltext
16. https://ivdc.chinacdc.cn/cnic/en/
17. https://www.globaltimes.cn/page/202412/1325884.shtml
18. https://www.globaltimes.cn/page/202501/1326299.shtml
19. https://www1.health.gov.au/internet/main/publishing.nsf/Content/cda-cdi3301h.htm
20. https://www.sciencedirect.com/science/article/pii/S1525861019303020
21. https://www.abc.net.au/news/2016-03-16/herberton-hospital-deaths:-authorities-responded-appropriately/7251358
22. https://www.globaltimes.cn/page/202311/1302543.shtml
23. https://www.globaltimes.cn/page/202306/1291955.shtml
24. Data from Sullivan Nicolaides Pathology (2018-2024). Respiratory virus weekly report. Accessed 06.01.2025
    https://www.snp.com.au/clinicians/results-and-reporting/infectious-disease-reports/#AnchorResp
25. https://www.chinadaily.com.cn/a/202412/27/WS676ead20a310f1265a1d55ba.html
26. https://www.financialexpress.com/life/hmpv-outbreak-in-china-know-all-about-symptoms-causes-and-treatment-option-of-this-respiratory-illness-3704235/
27. https://www.nationthailand.com/blogs/news/general/40044663
28. https://thetrumpet.ng/5-year-after-covid-19-chinas-human-metapneumovirus-hmpv-outbreak-sparks-fear-of-new-global-health-crisis/
29. https://www.ndtv.com/world-news/china-faces-new-virus-outbreak-five-years-after-covid-crisis-7385802
30. https://www.livemint.com/science/hmpv-outbreak-in-china-is-it-a-new-virus-how-is-it-similar-to-covid-19-is-there-any-vaccine-what-we-know-so-far-11736044379099.html
31. https://www.ndtv.com/world-news/china-faces-new-virus-outbreak-five-years-after-covid-crisis-7385802
32. https://www.independent.co.uk/asia/china/hmpv-china-human-metapneumovirus-outbreak-symptoms-b2673687.html