For anyone who remembers the start of the covid-19 pandemic, the news of a bird flu virus infecting dairy cows across the US and a person exposed to the animals may raise the hairs on the back of their neck. But experts say we shouldn鈥檛 worry about a full-blown pandemic yet. Right now, the bigger concern is not having enough information to anticipate how the virus may act next.
鈥淎t this point in time, I would not think a pandemic is likely,鈥� says at Emory University in Atlanta, Georgia. 鈥淭he risk to humans is quite low. It鈥檚 not nothing, but it is very, very low.鈥�
Since 2021, a subtype of the bird flu virus, H5N1, has devastated global bird populations. It has also infected an increasing number of mammals including foxes, seals, mink and, most recently, cows.
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In late March, dairy cows across Texas, Kansas, Michigan, New Mexico and Idaho tested positive for the virus. A person also contracted it after interacting with the animals 鈥� the first known instance of H5N1 transmitting between a human and another mammal.
The individual鈥檚 only symptom is eye redness, and they are recovering, according to the US (CDC). But bird flu can be deadly in humans. About half of the roughly 880 people since 2003 have died from the virus. 鈥淎ny case of H5N1 is concerning because it is highly dangerous to humans,鈥� said at the World Health Organization (WHO) in a briefing on 3 April.
The good news is the virus hasn鈥檛 been transmitted between people. Plus, initial testing of samples from the infected person and cows don鈥檛 show mutations that would significantly increase that risk, according to the . 鈥淲hat we do know is that this particular virus is still very much a bird virus,鈥� says at St. Jude Children鈥檚 Hospital in Tennessee.
Yet he says each time the virus infects or transmits between mammals, it could acquire mutations that may make it more dangerous to humans. That is why the WHO says it is working closely with the CDC to track the virus. The US Department of Agriculture has also stepped up surveillance efforts.
鈥淚 think it鈥檚 hard to put [the outbreak] into full context right now. More information is needed,鈥� says at Johns Hopkins University in Maryland.
One unknown is whether the virus is spreading between cows. Evidence suggests that is the case, says at the American Association of Bovine Practitioners (AABP) in Ohio. For instance, cows in after those from a herd in Texas were introduced to the farm. 鈥淧robably our biggest question is how it is transmitted between cows,鈥� says Gingrich. 鈥淚f you don鈥檛 know how disease is spreading, it鈥檚 hard to prevent.鈥�
Additional genetic sequencing is needed to better understand the virus鈥檚 spread as well. Those efforts, which involve comparing samples from cows to those from wild birds, are underway but will take time, says Davis.
In the interim, the AABP is advising dairy farmers to provide workers with masks, gloves and other protective equipment to prevent the virus鈥檚 spread. People should also avoid raw milk and raw milk products, which can transmit the virus. Otherwise, the general public鈥檚 risk of bird flu is low, says Guest.
The CDC says current antiviral medications also work against the virus, and there are two vaccine candidates already in development. These would be effective against the current strain and are available for manufacturing, says the .
鈥淭hose who are in positions of response should be on high alert and should be doing as much active surveillance as possible, which they are,鈥� says Davis. 鈥淏ut if you鈥檙e an average consumer and you鈥檙e drinking pasteurised milk, don鈥檛 panic. Be aware, but don鈥檛 panic.鈥�
