Once again, the world shuffles closer to the Flupocalypse. GPs and hospitals are on sniffle alert for visitors freshly flown in from China, who may be harbouring the potentially lethal H7N9 bird flu virus and quietly seeding a pandemic. We’re not there yet, thankfully, but a packed London briefing on Wednesday was not for those of a nervous disposition.
A panel of Britain’s top virologists barely smiled as they reeled off their findings. H7N9 has never before crossed from birds into humans but, according to genetic analysis, it has suddenly hurdled the species barrier several times in different parts of China. It evaded the well-established protocols of influenza surveillance and was rumbled instead through monitoring of pneumonia, suggesting exceptional virulence. By the time pneumonia sets in, Tamiflu can’t help, because it only works in the early stages. And unlike other bird flu outbreaks, maturity does not confer immunity: the youngest patient is two, the oldest 81.
As of yesterday afternoon, according to the World Health Organisation, H7N9 had infected 126 people and killed a fifth of them. By comparison, the Spanish flu pandemic of 1918 killed roughly 3 per cent of the people it infected (though at least 40 million people still died) and a previous H7N7 outbreak in the Netherlands mostly caused conjunctivitis.
The first H7N9 case outside China has cropped up, in Taiwan; two family clusters are being investigated to see if the virus has skipped from person to person. The disease is circulating in chickens right across China, which has become the world’s crucible for new forms of bird flu through its poultry markets and the culture of people sharing homes with animals. Everyone who has contact with a bird becomes a potential reservoir for “reassortment”, a kind of genetic shuffling that brews new viruses. One day, doomsayers warn, bird flu will swap genes with a human flu virus to concoct a super-virus armed with the extreme infectiousness of seasonal flu and the lethal nature of the avian type.
A virus needs to show five key mutations to be extremely transmissible (one, for example, confers the ability to “stick” in the upper respiratory tract); H7N9 possesses two of them. Experiments with ferrets should reveal over the next fortnight whether it could take those last three steps towards pandemic potential in mammals.
But the end is not quite nigh. Perversely, bird flu with a high death rate is good for humanity, because the virus usually dies with the patient, limiting its spread. H7N9 has not yet been detected in British fowl. And, comfortingly, there are no plans to drop the manufacture of seasonal vaccines in order to churn out pandemic flu vaccine (the world does not have the capacity comfortably to produce both).
The politics is also cheering: unlike in previous outbreaks, China has moved swiftly in the global public interest. Chinese officials had throat swabs of the first H7N9 patients on March 24; five days later, the full genomes were made public.
Jeremy Farrar, the soon-to-be director of the Wellcome Trust, who dialled in to Wednesday’s briefing from Vietnam, also inspires confidence. I once spent several days with him in Ho Chi Minh City, in the aftermath of an epidemic. He commands enormous respect in both government and the WHO. If he had a slogan, it would probably be Keep Calm and Convey the Uncertainty. He will not be complacent – he lost a friend and WHO colleague, Carlo Urbani, to Sars.
The only grotesquely comedic element to the current scare is this: unlike other variants, H7N9 doesn’t sicken chickens. If we find ourselves shivering and coughing our way to bird flu oblivion, we all know who’ll be having the last cluck.