TIME: “H7N9 meets two of the three conditions for becoming a pandemic”
From TIME Magazine, via Yahoo, here are three key facts, quoted below:
- So far, the World Health Organization reports that 246 people, virtually all in China, have been infected with H7N9 since the virus was first identified last year, and nearly a quarter of them have died….
- Because H7N9 does not make birds sick, it’s nearly impossible to distinguish infected poultry from healthy animals….
- What concerns health experts is that H7N9 meets two of the three conditions for becoming a pandemic—it is widespread among birds, and it can pass from birds to people. So far, it does not appear to transmit easily from person to person, but if it did, says Frieden, “that would be a big problem. The likelihood of having a pandemic would be much, much higher.”
(Pandemics, by definition, cross international boundaries and continents.)
Following the course of bird flu has been a pet project of mine, since I have always thought there will be a global flu pandemic and that it will start in China.
So I have been monitoring the various strains in humans and poultry for about eight or nine years. I was one of a hundred or so involved in a market based system of prediction of the course of bird flu, the Iowa Health Prediction Market on Avian Flu in 2008 — here is my blog post that explains the results of that very successful and highly accurate predictive market — which I believe should be immediately re-started. Every participant started with $100 virtual dollars. The better your bets on the future, the more money you made, and the worse your bets, the more money you lost. (The Iowa Health Prediction Market on Avian Flu was funded by the Robert Wood Johnson Foundation and run by Phil Polgreen and Forrest Nelson, the directors of the Iowa Electronic Health Markets. Nelson and Polgreen are both professors at the University of Iowa, in Iowa City, Iowa, and the Iowa Health Prediction Market on Avian Flu was run at the University of Iowa.)
The reason that predicting what will happen is so important when dealing with a potential pandemic, is that preventing a pandemic or dealing with it depends (mostly) on deploying scarce resources effectively. Ultimately, in an actual pandemic, everyone — except the well-prepared — will end up muddling through the experience. And the quality of your own muddling through will depend on your own degree of preparedness.
Furthermore, the pandemic experts may be damned if they do, and damned if they don’t scenario on sounding the pandemic alarm. If they do and nothing happens, they will be ignored, accused of scaring people unnecessarily; and if they wait until it happens, they will be attacked for not preparing the public or elected officials. Actually, risk communication expert Peter Sandman says the the “experts are ‘dammed’ if they fail to warn about a disaster that materializes…but merely ‘darned’ if they warn about one that doesn’t.”
The Vancouver Sun reports:
“Risk communications experts Peter Sandman and Jody Lanard have been monitoring developments in influenza and other infectious disease for over a decade.
They suggest this situation has the public health world over a barrel. If they sound alarms about H7N9 and the virus doesn’t quickly take off, they’ll be dismissed. If they don’t sound alarms, and the virus does trigger a pandemic, they’ll be pilloried.
“This is a high-magnitude risk whose probability cannot be estimated with any confidence,” they said via email.
“And whatever is conveyed, no matter how nuanced, if the outcome goes in the other direction, people will remember the experts as having overly alarmed them, or as having failed to warn them.”
Re-starting The Iowa Health Prediction Market on Avian Flu removes the problem of experts who are legitimately concerned, but reluctant to go public. The market will remove this problem so the public and others get the best and most accurate human prediction possible: a crowd-sourced, collective consensus the market will produce, giving policy makers and the public the best and most accurate method discovered to date of evaluating the pandemic risk.
Should H7N9 infect a human who also has the run-off-the-mill flu that is already transmittable from human-to-human (which the experts call coinfection) we would expect that the H7N9 virus and the non-H7N9-flu could mutate inside that human (they use the term reassortment, not mutate) and could possibly combine in some fashion to form a new mutation of H7N9 that might — that’s might — pass easily from human-to-human.
The Chinese government has already found a boy who has been coinfected with H7N9 and an existing flu that is transmittable from human-to-human in the first wave of H7N9 cases in early 2013, but the result was not a reassortment of H7N9 into an easily human-to-human transmittable disease.
“The ECDC (European Center for Disease Prevention and Control) said the outbreak in China remains localized, with the virus mainly transmitted sporadically to humans who have close contact with the animal reservoir, presumably live poultry. Though the H7N9 virus doesn’t appear to have the capacity for efficient human-to-human spread, new reassortants with seasonal flu strains could arm it with the ability to transmit more easily, a situation that bears close monitoring, the organization added.
Seasonal flu activity is at high levels and still increasing in China, with all three strains circulating, the World Health Organization (WHO) said yesterday in its global flu update. In southern China the dominant strains are H3N2 and the 2009 H1N1 virus, while the northern part is seeing mainly 2009 H1N1.
Brisk seasonal flu activity is occurring alongside rapidly accumulating H7N9 cases in the eastern and southern provinces. Last spring China’s surveillance system picked up at least one coinfection case, that of a 15-year-old boy who recovered after he was sick with both H7N9 and H3N2.”
The chances of H7N9 becoming transmittable from human-to-human depends on only one thing: the number of humans it infects. This increases the chance of coinfection, and a spike in H7N9 cases during normal flu season increases those coinfection odds.
The key point is that the degree of difficulty for H7N9 to become transmittable from human-to-human is far lower than the high degree of difficulty of the passing from bird-to-human, which H7N9 has already accomplished.
But, H7N9 can also infect pigs and ferrets. According to this report from the South China Post, pigs are another possible route to H7N9 becoming transmittable from human-to-human, by infecting a pig that also has swine flu.
Should the number of Chinese who become ill with H7N9 reach into the thousands, then I think there are reasonable odds that H7N9 will mutate into being transmittable from human-to-human. But the number needed for that to occur could be higher or lower, it simply depends on who becomes infected with H7N9 and if they already have any other flu that is human-to-human transmittable.
As the global health experts point out, one key indicator will be the count of those who become ill with H7N9 in China in the next six weeks, since the Lunar New Year is similar to the mass travel prior to Thanksgiving in the U.S. As the Associated Press reported today, “migrant workers cram trains” that are “jam-packed” on their way to celebrate the Chinese Lunar New Year, which is on Friday, January 31. This quote from AP may help put the scale of the travel that going on in China in perspective: “China’s Lunar New Year migration is often referred to as the largest movement of people anywhere, with 3.6 billion trips of all lengths by bus, plane and train expected to be made over the 40-day travel rush.”
This is why it has caught the attention of the global health officials, but it’s also irrelevant if there is no human-to-human transmission of H7N9. There is one slight caveat, however, from Bernhard Schwartlander, the World Health Organization’s representative in China, as reported a week ago in ChinaDaily:
Human-to-human transmission of the H7N9 bird flu virus might occur on a limited scale in China, the World Health Organization representative to the country said on Monday….”Since October, only one cluster was detected where human-to-human transmission might have occurred. We continue to expect only sporadic human cases,” Schwartlander said.
Reports of new H7N9 human infections continue, presumably infected by contact with chickens. From Infectious Disease News today: “in the past two days, WHO has reported 21 additional cases of human infection with influenza A(H7N9) virus in China.”
There have been two waves of human infections of H7N9 in China. As reported by CIDRAP, “cases in the second wave are piling up faster than during the first wave. The first wave reached 136 cases in 158 days, according to a CIDRAP analysis of illness-onset dates. But it took the second wave, which began in early October, to reach the same number of cases in only 105 days. And the pace in the past few weeks has been especially brisk.” CIDRAP says “the case-fatality rate (CFR) ranges from 20% to 30%.”
Simply put, we will know if there is anything to worry about over the course of the next six weeks, perhaps sooner, but “so far there have not been any cases in which one person transmits the flu to another, and the latter transmits the virus to a third person,” Li Lanjuan, an academician at the Chinese Academy of Engineering and a specialist in H7N9 prevention, told Xinhua.”
As TIME magazine put it, “health officials can only watch and wait for a potential pandemic.”