While many of the posts mention a “mysterious respiratory” illness, experts have said the virus is not unfamiliar to Australians and it’s unlikely to warrant panic.

What is HMPV and what are the symptoms?

There are no vaccines for HMPV but severe cases can be treated at hospitals.

“In young children, the elderly, and those who are immunocompromised, HMPV can lead to severe cases and can move to the lower respiratory tract and may lead to pneumonia,” she said.

What are experts saying about it?

She said people should take “necessary precautions” such as getting PCR tests to identify viruses, staying home if battling an infection, and wearing a mask in public to “protect our most vulnerable”.

What’s the situation in China?

Senanayake said genomic data would also guide vaccine development, which is already underway.

Is HMPV like COVID-19?

“HMPV can certainly make people very sick, and high case numbers are a threat to effective hospital services, but the current situation in China with high HMPV cases is very different to the threats initially posed by SARS-CoV-2 resulting in the COVID-19 pandemic,” she said.

“Again, very different to the COVID-19 pandemic, where a new lung disease was seen, there was little information on how the virus may vary and spread, and we had no initial diagnostic tests.”

What is the government saying?

“It’s a type of illness we’re pretty familiar with.”