The scientific community in the USA has been put on alert after it was announced that bird flu has jumped to cows and is spreading rapidly in flocks.
Just four years after the start of the Covid pandemic, the unprecedented spread of a new strain of H5N1, or bird flu, among U.S. dairy cows is a reminder of our vulnerability to new viral threats, Politico reports in an extensive report.
Jeremy Farrar, head of the World Health Organization (WHO), said last week that the risk of transmission to humans from the new strain was of “tremendous concern”. Bird flu rarely infects humans, but is often fatal when it does. According to the WHO, the case fatality rate in humans since 2003 is 52%.
Why are scientists so worried?
The fact that the virus appeared in mammals such as cows suggests that the virus has mutated and brings it one step closer to infecting humans. Bird flu has been considered a pandemic threat for decades, but, as its name suggests, it has primarily affected birds.
“The news confirms flu’s ability to surprise us,” Paul Digard, a professor of virology and flu expert at the University of Edinburgh, told Politico. “Historically, we viewed cows as very low risk for influenza A (a subtype of influenza that causes disease in humans and includes the virus now spreading in cattle). This takes the threat assessment up a notch,” Dugard added.
How widespread is the new strain?
It is probably wider than previously reported. “I think the spread of infection will be much larger than the number of farms that has been reported,” said James Wood, head of the department of veterinary medicine at the University of Cambridge.
The detection of viral RNA in milk shows that the disease is more widespread than previously thought, Wood explained. As of Thursday in the US, about one in five retail milk samples tested positive for viral fragments.
Is this milk safe to drink?
Viral particles have been detected in commercial milk in the US, but this does not necessarily mean it is unsafe to drink. Pasteurization is effective at killing the flu, and US authorities said there was no evidence that the RNA particles detected in the milk were capable of infecting anyone.
US federal agencies (USDA, USFDA, CDC) have reiterated that “the commercial milk supply is safe.”
They also add that pasteurization is “likely” to inactivate the avian influenza virus in milk, while acknowledging that “studies on the effects of pasteurization on viruses have not previously been completed [υψηλής παθογονικότητας γρίπης των πτηνών] (like H5N1) in cattle milk’.
The detection of viral RNA in American milk is probably of little concern to Europe. US milk imports into the EU are “very close to zero” and “statistically insignificant in terms of trade,” an EU official told Politico.
What is the danger of the new strain to humans?
So far, the risk to humans is limited, but there’s a lot we don’t know about the strain since it’s new. There has been at least one human case of the new strain, but no evidence of human-to-human transmission, a key indicator of a pandemic threat.
The risk is that the virus mutates further and eventually develops the ability to infect humans more easily. The more widespread the virus is among animals, the more opportunities it has to do just that.
Has the new strain been detected in Europe?
For now, EU countries are closely monitoring developments. “The infections of dairy cattle in the US are with a strain of H5N1 that has not been detected in Europe. We are closely monitoring the situation and its possible evolution,” a spokesperson for the European Food Safety Authority (EFSA) told Politico.
A spokesman for the European Commission added that it is closely monitoring any genetic evolution of the virus, but that the threat to human health remains low for the general public. Digard, meanwhile, says it would be wise to check dairy herds in the UK for the new strain, even though there is no sign yet that it has escaped from North America.
In the EU, EFSA recommended increased surveillance of mammals, especially those near poultry facilities affected by avian influenza.
Do we have bird flu vaccines?
There are vaccines that could work against bird flu, but it’s not yet clear how effective they would be against a particular strain and how quickly companies could ramp up production.
A GSK spokesperson told Politico that the company has a contract with the EU’s Health Emergency Preparedness and Response Authority to produce 85 million doses of the pandemic preparation vaccine, Adjupanrix, if needed. Adjupanrix is a “mock” flu vaccine that could be adapted to any flu strain that emerges as the cause of a pandemic.
Meanwhile, a spokesperson for the European Commission confirmed that it has entered into a joint contract with GSK and CSL Seqirus for the companies to deliver customized flu vaccines if needed in a pandemic.
Andrew Fenwick, a spokesman for CSL Seqirus, told Politico that the company’s zoonotic flu vaccine will likely protect against the strain currently circulating in the US.
The European Medicines Agency has also approved AstraZeneca’s pandemic flu vaccine, which was tested using an H5N1 strain.
Source: protothema.gr
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