China, hMPV, and the `Fog of Flu'

#18,526

China has a well-deserved reputation for treating `bad news' as a national security issue. Anything that might cause economic harm, societal distress, or put the CCP in a bad light is either `sanitized' or suppressed by the government run media. 

• The 2002 SARS outbreak was hidden from the world for months (see SARS and Remembrance), until it turned up in Hong Kong in 2003. 
• China often only belated reports avian flu outbreaks (see The Winter Of Our Disbelief  and  The Skies Aren't The Only Thing Hazy In China)
• China was slow to release details on the 2020 COVID outbreak and appears to have covered up millions of COVID deaths (see JAMA Open: Excess All-Cause Mortality in China After Ending the Zero COVID Policy).
• And just over a year ago China was less-than-forthcoming about an outbreak of severe pneumonia (see Taiwan MOH Statement On Respiratory Outbreak In Mainland China).

China obviously isn't alone in `managing' bad news (see The Wrong Pandemic Lessons Learned). Their success in these matters has shown the world there is little downside to selective reporting (see From Here to Impunity).

What we are left with is a `fog of flu', where internet rumor and speculation rushes in to fill the vacuum left by official silence.  

As I mentioned yesterday, there are numerous unconfirmed reports of a `mystery' viral outbreak in China.  Typical reports suggest overcrowded hospitals, and even increased crematory activity. 

Unofficially, hMPV (Human Metapneumovirus) - which was only first isolated in 2001 - has been cited by the media as a likely cause (see Newsweek's HMPV: China's Neighbors Respond Amid Virus Outbreak).

China's most recent weekly influenza report (week 52) - published on Jan 2nd -  doesn't specifically mention hMPV, but does provide the following graphic which shows an H1N1 dominant flu season, albeit with a fairly high number of non-influenza positive cases (particularly in Northern Provinces). 

Most winters, Influenza A viruses only cause about 15% of acute viral infections. The rest come from a variable hodgepodge of other viruses, including RSV, Influenza B, Adenoviruses, Rhinoviruses, HCoVs, and Human Metapneumoviruses. 

Last January's ISIRV: Comparative Mortality in Patients Hospitalized With influenza A/B virus, RSV, Rhinovirus, Metapneumovirus or SARS-CoV-2, found (unsurprisingly) that COVID was still deadlier than influenza A. 

The surprise came in finding that - among those sick enough to be hospitalized - Influenza A&B, RSV, Rhinovirus, and hMPV all had roughly the same 30 day mortality rate.

3.3 Crude 30-day mortality

Crude mortality at 30 days following admission accumulated to 18% for SARS-CoV-2 infections, 9% for influenza A, 11% for influenza B, 10% for RSV, 8% for rhinovirus and 9% for hMPV infections (Table 1, Figure 2). Crude SARS-CoV-2 mortality was higher than for all other viruses, though a progressive decline in mortality over the course of the pandemic was found (March–Aug 2020: 25%, Sept 2020–Feb 2021: 21%, March–Aug 2021: 14%, Sept 2021–Feb 2022: 14%). Crude mortality for all non-SARS-CoV-2 viruses was comparable (Table 1, Figure 2).

3.4 Covariate-adjusted 30-day mortality

Following adjustment for covariates, 30-day mortality odds ratio (OR) for SARS-CoV-2 infection, regardless of pandemic phase, was 2.70 (95% CI: 1.98–3.77) versus influenza A. No differences were found in adjusted ORs for 30-day mortality of influenza B, RSV, rhinovirus and hMPV infections (aOR influenza B: 1.05 (95% CI: 0.67–1.64), aOR RSV: 1.05 (95% CI: 0.63–1.71), aOR hMPV: 0.93 (0.54–1.55) and aOR rhinovirus: 1.00 (95% CI: 0.65–1.52, influenza A as reference, Table 2). In this cohort, age was related to mortality following hospitalisation, while an association with comorbidity was not apparent.

What isn't well established is how likely each of these viral infections is to put someone in the hospital.  

A 2019 study, however (see “Differential risk of hospitalization among single virus infections causing influenza‐like illnesses” suggests - based on limited data - that children with RSV or hMPV are more likely to be hospitalized than with influenza A or B and other common viral infections. 

While hMPV is a plausible cause of the rumored outbreak in China, this doesn't get us any closer to knowing what is actually happening there. The CCP exercises strict control over the media, and much of what we do hear comes from the dissident press, which have their own agenda.

While we wait for more news, over the next few weeks hundreds of millions of people in China (and all across Asia) will travel home for the Lunar New Year (Jan 29th), which constitutes the largest annual human migration on earth.

Chunyun - or the Spring Festival travel season - begins about 15 days before the Lunar New Year and runs for about 40 days total. 

If there is truly something unusual spreading in Northern China - and that has yet to be established - then we might start seeing reports from other provinces, and from neighboring countries, that will help clarify matters. 

Regardless of what happens with China, the next global public health crisis is not only inevitable, it may be a lot closer than we think.