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What’s behind the post Covid ‘mysterious’ pneumonia outbreaks in China?

by tbhad

The Wire, New Delhi

Amid an ongoing and fresh outbreak of what has emerged as “unknown pneumonia” in China leading to crowding at healthcare facilities in northern China, the government of the country has ruled out the presence of any new or unknown pathogen. This, at least as of now, should put to rest fears of a bigger outbreak which could have pandemic potential.

Quoting official conversation with Chinese health authorities from the Chinese Center for Disease Control and Prevention, and the Beijing Children’s Hospital, the World Health Organisation (WHO) said on November 23 that the upsurge in hospital admissions of children were due to Mycoplasma Pneumoniae – a bacterial infection – from May; and Respiratory Syncytial Virus (RSV), adenovirus and influenza – all viral infections – from October this year.

All these bacterial and viral infections are well known and treatments to these are available – unlike in case of a novel pathogen (a virus or bacteria).

The recent outbreak in China brought back eerie memories of the Sars-Cov-2 (novel coronavirus) outbreak.

It was also described as pneumonia of “unknown aetiology (unknown cause)” in one of the first statements of the WHO that was published after the outbreak of COVID-19. But now, the role of any unknown pathogen has been ruled out, at least, for the time being, while accepting the surge in cases.

“[The] Chinese authorities advised that there has been no detection of any unusual or novel pathogens or unusual clinical presentations, including in Beijing and Liaoning, but only the aforementioned general increase in respiratory illnesses due to multiple known pathogens,” the WHO has said

On November 22, a day earlier, the WHO made its first formal statement regarding the outbreak in China. Various images circulated on social media in which hospitals, especially treating children, were shown to be overwhelmed. In the November 22 statement, the WHO had said it had sought more information from China.

The WHO move was necessitated by a report on ProMed on November 21 which spoke of undiagnosed pneumonia epidemics going on in China. ProMed is an international forum that identifies infectious diseases outbreaks globally, and is usually the first platform to alert the global scientific community about them – as it did for Covid-19.

“With the outbreak of pneumonia in China, children’s hospitals in Beijing, Liaoning and other places were overwhelmed with sick children, and schools and classes were on the verge of suspension,” ProMed reported.

The WHO wanted to know whether there were “clusters” of “undiagnosed pneumonia” in Beijing and Liaoning and if the current outbreak was a general pattern of increase in respiratory illnesses.

‘Could be RSV or HMPV’

The Wire spoke to three experts and all of them, by and large, made observations similar to the WHO’s latest statement on the current outbreak.

“Since there are children [who are mostly infected], it could be RSV or Human Metapneumovirus (HMPV) – both known to cause respiratory illness in children,” said Shahid Jameel, a virologist. Jameel is currently a research fellow at the Oxford University’s Green Templeton College.

RSV, according to the US Centers for Disease Control and Prevention (US-CDC) is a common viral respiratory infection that usually causes mild, cold-like symptoms and people can recover in a week with or without use of antibiotics. However, some serious cases may require hospitalisation.

Similarly, Mycoplasma Pneumonia is a bacterial respiratory system which is usually considered mild but serious cases be hospitalised. Both of them are transmitted through droplets of an infected person or a close contact with her.

“There have been RSV outbreaks elsewhere [also apart from China ]after good years due to quarantine and other restrictions [being lifted],” Jameel added.

The WHO also said something similar. “Some of these increases are earlier in the season than historically experienced, but not unexpected given the lifting of COVID-19 restrictions, as similarly experienced in other countries,” it explained.

Amesh Adalja, a senior scholar at Johns Hopkins Center for Health Security, says the current outbreak in China seemed to mimic what happened in the US earlier.

“It appears that this outbreak is likely the result of several known respiratory pathogens, including Mycoplasma Pneumoniae, all attacking at once — similar to what happened in the US last year with simultaneous outbreaks of RSV, influenza, and COVID-19,” he said in an emailed response to The Wire.

Why now? Why China?

Incidentally, China had followed what was called ‘Zero Covid’ policy. It locked up, as per stringent measures of lockdown for COVID-19, large swathes of the population for a very long time – longer than many other countries. This resulted in a scenario in which the population didn’t get exposed to other respiratory viruses or bacteria also, in the process.

And, once the measures were lifted this winter,  this population got exposed to all of them leading to the surge in cases. Moreover, not getting exposed to these pathogens for a long time could also have created what is known as ‘immunological deficit’ – a deficiency in natural immunity acquired against the pathogens due to exposure to them.

Bharat Pankhania, an infectious diseases expert with University of Exter Medical School, UK, believes the ‘deficit’ might not provide the complete answer to the ongoing outbreak.

“Immunological deficit is not surprising…but then you can have more people infected than expected because of circumstances like crowded schools, crowded shops, buses, trains…and there is winter now,” he said.

“So it’s very difficult to disentangle [whether] it is an immunological deficit, or is it environmental circumstances. Or perhaps both,” he added.

Nonetheless, Pankhania stressed that the fact that the patients responding to the drugs in this outbreak is a pointer to the fact that it is not an unknown infection. The Chinese authorities, per WHO, have also said there is no change in the presentation of these diseases vis-a-vis the patterns already known.

What next?

Currently, going by the data provided by the Chinese authorities, the WHO has assessed that the outbreak of the respiratory illnesses are caused by the known pathogens which are readily treatable with antibiotics, if needed. And, therefore, there was no cause of immediate alarm.

Both Pankhania and Adalja said the Chinese authorities must share data with the global scientific community. They must  publish the detailed findings of their inquiry besides sharing genome sequences of the samples tested.

The WHO has also added though information available is “limited” to “fully characterise” the overall risk even though winter season is known to create a spike in respiratory infections.

And sounding a cautionary note, it said it will continue to closely monitor the situation and would be in close contact with national authorities of China.

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