--- title: Bird Flu May Be Getting Better at Infecting Mammals description: Does that mean it will soon spread more easily among people? There’s reason for concern, say experts. canonical: https://time.com/6997774/can-bird-flu-infect-people/ author: Alice Park article:opinion: false article:content_tier: free article:published_time: 2024-07-12T14:34:29.000Z article:modified_time: 2026-10-19T07:44:19.543Z article:section: Health og:title: Bird Flu May Be Getting Better at Infecting Mammals og:description: Does that mean it will soon spread more easily among people? There’s reason for concern, say experts. og:url: https://time.com/6997774/can-bird-flu-infect-people/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt980c7033a891e242/698a58a0b21a9c5a3a50a314/GettyImages-1450374430.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 2097 og:image:height: 1180 og:image:alt: GettyImages-1450374430.jpg og:type: article twitter:card: summary_large_image twitter:title: Bird Flu May Be Getting Better at Infecting Mammals twitter:description: Does that mean it will soon spread more easily among people? There’s reason for concern, say experts. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt980c7033a891e242/698a58a0b21a9c5a3a50a314/GettyImages-1450374430.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # Bird Flu May Be Getting Better at Infecting Mammals > Sponsored content. Supplied in partnership with TIME. 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TIME Senior Correspondent Alice Park explains this latest outbreak of bird flu - also called H5N1 Avian Influenza - after officials reported the first death from virus in the U.S._  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Jul 12, 2024 2:34 PM UTC You’ve probably been hearing a lot about bird flu in the news lately. So, what is it? Do you need to worry, and can you protect yourself? TIME Senior Correspondent Alice Park explains this latest outbreak of bird flu - also called H5N1 Avian Influenza - after officials reported the first death from virus in the U.S.  by [Alice Park](https://time.com/author/alice-park/)  ## Alice Park Senior Correspondent Jul 12, 2024 2:34 PM UTC H5N1, known as bird flu, is becoming an increasing problem in the U.S. The virus normally only infects poultry and wild birds, but it's becoming more adept at infecting mammals; so far, it's infected cattle in [12 states](https://www.cdc.gov/bird-flu/situation-summary/index.html). A small number of people are also falling ill—[several dairy workers](https://www.cdc.gov/media/releases/2024/p-0703-4th-human-case-h5.html) have been contracted mild illnesses and recovered. The latest [research published in _Nature_](https://www.nature.com/articles/s41586-024-07766-6) suggests that the current strain may be more adept at infecting mammals like cows. Researchers led by Yoshihiro Kawaoka, a professor at the University of Wisconsin—Madison and the University of Tokyo, report that the current version differs from previous H5N1 strains and has mutations that make it easier for the virus to infect mammalian cells. Kawaoka says that this ability “is more than what we saw in the past with avian H5N1 viruses, but it is still limited.” The group tested virus obtained from infected cows in both mice and ferrets—the latter of which are a good model for how influenza viruses may act in people. Only one in four uninfected ferrets that were housed in the same cages as infected ones tested positive for H5N1\. But how well a virus spreads depends a lot on how much virus is present, and at the moment H5N1 in dairy cattle does not appear to concentrate in the respiratory tissues—meaning it’s not saturating airborne particles the animals may exhale and inhale. Instead, it’s primarily found in the mammary glands, and therefore in the milk the cows produce. **Read More**: [_We Are Not Safe from Bird Flu Until We Protect Farmworkers_](https://time.com/6987552/bird-flu-farm-workers/) That’s a concern for dairy workers and anyone drinking raw, unpasteurized milk. “We should be concerned because there is a huge amount of virus present in milk,” says Kawaoka. “The biosecurity in farms is limited, so there is a lot of virus out there, and it’s very important to contain this virus as soon as possible.” Kawaoka and his team recently quantified the amount of virus in the milk of an infected cow in a [report](https://time.com/6988603/bird-flu-milk-pasteurization/) published in the [_New England Journal of Medicine_](https://www.nejm.org/doi/full/10.1056/NEJMc2405495). They found a very high number of infectious particles in a single milliliter of raw cow’s milk. Pasteurization inactivated the virus, but Kawaoka says the effectiveness of the heat pasteurization depends on how long the milk is treated and how much virus is present. If the virus doesn’t spread easily among ferrets, how is it transmitting so readily among cows? Kawaoka says it’s not likely that cows are actually passing the virus among themselves. Instead, because H5N1 is so highly concentrated in the mammary glands and milk, it’s likely that the virus is spreading via contaminated milking machines that aren’t cleaned thoroughly between each milking. The results are reassuring in the sense that for now, H5N1 doesn’t seem to pass easily from animal to animal. But the fact that the virus is different from previous strains and has picked up the ability to more easily infect mammals is concerning, says Kawaoka. Health officials are closely monitoring samples from both infected cattle as well as the handful of dairy workers who have tested positive for H5N1 to ensure the virus isn’t mutating further to spread easily among people. If it does, [they say they are ready](https://time.com/6991893/is-there-a-bird-flu-vaccine-h5n1/) with three vaccines, currently in the vaccine stockpile, that can protect against severe infections. ## Transcript [00:00] You've probably been hearing a lot about bird flu in the news lately. [00:05] New cases of the bird flu are raising alarms among health officials [00:08] America's first severe human case of h5n1 bird flu. [00:14] So what is it? Do you need to worry and can you protect yourself? [00:18] Bird flu is also called h5n1 Avian Influenza. [00:23] This recent outbreak began in 2024, [00:26] and what has experts concerned is that it's not only infected millions of birds, [00:31] but the virus has also spread to dairy cattle and other mammals, [00:36] including goats, foxes, and house cats. [00:39] And increasingly, it's been diagnosed in humans. [00:42] A US man over age 65 with other health conditions [00:46] became the first to die with h5n1 infection in early 2025. [00:52] Breaking tonight the nation's first human death from the bird flu just reported. [00:56] Down from Louisiana here. The Department of Health There. [00:59] Listen to this. The first person has died from bird flu. [01:03] Genetic analysis of the virus from that man suggests that [01:07] h5n1 mutated in his body after he became infected. [01:12] The US Centers for Disease Control and Prevention [01:15] has said these mutations are concerning, [01:17] but not a cause for alarm. [01:19] Yet, symptoms of h5n1 infection can resemble those of more common illnesses. [01:26] Many of the people in the US who have caught bird flu are [01:29] farm workers who have come into direct contact with infected cattle or poultry. [01:34] They have developed relatively mild symptoms, [01:37] including conjunctivitis like eye issues, [01:40] eye redness, and discharge from the eyes. [01:43] Dairy workers who milk infected cows are especially at risk, [01:47] since the virus can enter their eyes from milk that sprays into their face. [01:51] Bird flu can also cause respiratory and classic flu like symptoms, [01:56] including cough, runny nose, [01:58] fever, sore throat, body aches, headaches, [02:02] fatigue, shortness of breath, [02:04] and even pneumonia, the CDC says. [02:06] As bird flu continues to spread, [02:09] work on a vaccine is underway to protect the public in the event of a pandemic. [02:14] Several companies, including Maderna, [02:17] Pfizer, and Glaxo Smith Kline, [02:20] which is working with Kvak are developing an MRNA vaccine, [02:25] using the same technology that was used in the COVID 19 shots. [02:29] In July, the US government awarded [02:31] Maderna $176 million to develop its updated MRNA h5n vaccine. [02:39] All of these MRNA vaccine candidates are in [02:42] early stages of testing in people for safety and efficacy. [02:47] In 2024, scientists led by a team at the CDC reported that [02:52] an MRNA based h5n1 vaccine helped [02:56] ferrets generate strong antibody responses against the virus. [03:00] Vaccinated animals survived a lethal dose of [03:03] the virus while unvaccinated ferrets died from their infection. [03:08] While creating an MRNA vaccine can be done quickly, [03:12] testing the shot in clinical trials will take longer. [03:15] So in the meantime, several existing vaccines, [03:19] which don't use MRNA technology, [03:21] but do target previous strains of h5n1 exist in the national stockpile. [03:27] Health experts expect they would still provide some protection against severe disease. [03:32] Because the virus is spreading among poultry and dairy cattle, [03:36] the outbreaks are leading to egg rationing and shortages and have led to higher prices. [03:42] While milk prices are not expected to go up, [03:45] the US FDA now tests for the virus in [03:48] commercial milk and other dairy products on a regular basis. [03:51] The agency also advises staying away from raw milk, [03:55] which is not pasteurized, [03:57] a process that can kill the virus. [03:59] Some experts believe dairy workers and others who have [04:03] close contact with animals likely to be infected, [04:06] such as poultry and cattle, [04:07] should be vaccinated to protect them from infection. [04:11] The CDC says that the risk of bird flu is still low for the general public. [04:16] And currently there are no recommendations for anyone [04:19] in the US to get vaccinated against h5n1. [04:23] As with all viruses, [04:25] experts caution that everyone wash their hands carefully, [04:28] avoid touching their face, [04:30] and wear a mask if they may come in contact with infected animals. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/6997774/can-bird-flu-infect-people/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/6997774/can-bird-flu-infect-people/"},"headline":"Bird Flu May Be Getting Better at Infecting Mammals","datePublished":"2024-07-12T14:34:29.000Z","dateModified":"2026-10-19T07:44:19.543Z","description":"Does that mean it will soon spread more easily among people? 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