Avian Flu Diary: Russia: Anna Popova On The Potential For H5N8 To Transmit Between Humans

#15,860

Three weeks ago we saw the announcement by Anna Popova - Chief State Sanitary Physician of the Russian Federation - of the first detection of human infection with avian H5N8 (see Russian Media Reports 7 Human Infections With Avian H5N8).

Popova often uses press conferences or interviews to make surprise announcements (see here and here), and is frequently quoted by the Russian media.

Since this announcement, we've see confirmation by the WHO and a risk assessment by the ECDC, both of which determined the risk of human infection to be low or very low.

The WHO summarizing:

As mentioned earlier, all the seven cases with PCR-positive results were clinically asymptomatic. All close contacts of these cases were clinically monitored, and no one showed signs of clinical illness. Infections with avian influenza viruses of the same clade (H5 clade 2.3.4.4) have been reported from China since 2014 in people with exposure to infected birds. The likelihood of human infections with influenza A(H5N8) viruses has been considered to be low.

While the ECDC stating:

This assessment is based on very limited data and there is therefore considerable uncertainty regarding the conclusions reached. The risk of infection related to avian influenza influenza A (H5N8) virus for the general public is assessed as very low, and for occupationally exposed people as low.

Nevertheless, earlier this week the WHO prudently called for the development of a Candidate Vaccine Virus (CVV) against avian H5N8 (see WHO: Candidate Vaccine Viruses for Pandemic Preparedness - March 2021), just in case it becomes a more common zoonotic threat.

While primarily considered a disease affecting birds, we have seen some evidence of H5N8 jumping to mammals (see MAFRA: H5N8 Antibodies Detected In South Korean Dogs (Again)), and some research (see Sci Rpts: H5N8 - Rapid Acquisition of Virulence Markers After Serial Passage In Mice) suggesting that H5N8 might someday acquire the genetic changes that would make it a human health threat as well.

A 2017 editorial in the Journal Virulence (see J. Virulence Editorial: HPAI H5N8 - Should We Be Worried?) reviewed and summarized the literature, and found enough reasons to be concerned over the future evolutionary path of H5N8, stating that:

The extensive distribution of HPAI H5N8, as well as the gene reassortment with other circulating avian viruses already observed for H5N8 suggests there is a potential risk for human cases of H5N8 infections.

So, while the threat to humans posed today by H5N8 may be low or very low, there are no guarantees it will remain so. Viruses evolve, and while that evolution is unplanned and random - it can sometimes lead to dangerous species jumps - as we've seen demonstrated so vividly with SARS-CoV-2.

Overnight the (often hyperbolic) Russian media has been filled with reports dozens of reports on an interview of Anna Popova by TASS on the 1 year anniversary of the Coronavirus pandemic - where she also warned on the possibility (or even likelihood) of human transmission of H5N8.

It isn't clear whether any of this is based on additional or unpublished data, or if it is merely speculation on Popova's part. It has, however, become a bit of a cause célèbre overnight in the Russian media, and is thereworth worth mention.

As always, Caveat Lector.

Although we have the original TASS interview in Russian, the following English language summary comes from the Moscow Times.

Russia Warns of H5N8 Bird Flu Transmission

The mutating H5N8 strain of avian flu has a high risk of human-to-human transmission, Russian authorities warned Friday.

Anna Popova, who heads Russia’s health watchdog Rospotrebnadzor, made the prediction nearly a month after scientists detected the first case of H5N8 transmission to humans at a southern Russia poultry farm.

“There’s a fairly high degree of probability” of human-to-human transmission forecasts, Popova told the state-run TASS news agency.

Though people can get infected with other bird and swine flu subtypes, the H5N8 strain that is lethal for birds has never been reported to have spread to humans.

“This is likely to happen. Colleagues say that the mutation is continuing very actively,” Popova said.

Popova noted that Rospotrebnadzor and the Siberia-based Vektor state research laboratory “have the time” to develop a test kit and a vaccine, “then monitor the situation.”

“If we won’t need it, it’ll be a lucky break. But if necessary, we’ll be ready,” Russia’s chief sanitary doctor told TASS.

(Continue . . . .)

Long time readers of this blog know I consider it a mug's game to try to predict which pathogen will make the next species jump to humans, and spark a pandemic. There are simply too many contenders out there to pick a favorite.

I just assume another virus will make that leap, and it will probably happen sooner rather than later.

By the same token, I wouldn't bet against a virus like avian H5N8, even though I can think of a dozen more likely pandemic threats. After all, 16 months ago no one had ever heard of the virus that causes COVID-19.

For some past blogs on other - perhaps more plausible - pandemic contenders, you may wish to revisit: