Cows stand at a feedlot in Quemado, Texas on June 14, 2023.
Brandon Bell |
US health authorities are monitoring bird flu in humans and making preparations to combat it, but at the same time stress that the risk to the general population remains low.
A strain of bird flu called H5N1 has been confirmed in dairy cows in nine U.S. states and two people, while a global outbreak is occurring in poultry and other animals. The latest case was This was announced on Wednesday in the case of a worker on a dairy farm in Michigan. A child in Australia was also recently infected with bird flu, the country announced on Tuesday.
Since 2020, the H5N1 virus has been spreading among an increasing number of animal species around the world, but its discovery in U.S. livestock earlier this year was an unexpected turn for health authorities. In rare cases, bird flu viruses can jump to humans, causing mild to severe symptoms that may require hospitalization.
There is currently no evidence that H5N1 is transmitted from person to person. The US Centers for Disease Control and Prevention has also stated that the risk of infection is higher among farm workers than among the general population.
Still, the U.S. government and state and local health authorities are monitoring new and spreading infections in humans and animals. Federal agencies in the U.S. and elsewhere have also been monitoring the H5N1 virus for years to monitor its evolution.
The U.S. government has long stockpiled vaccines and medicines in case of a possible bird flu pandemic. Last week, it began preparing nearly five million doses of vaccine that is expected to work well against H5N1, among other measures, the Department of Health confirmed to CNBC.
Some infectious disease experts told CNBC the U.S. government appears to be fundamentally prepared if bird flu spreads further and more easily crosses over to humans, especially compared to how well prepared the country was for the Covid pandemic. The experts said most of the necessary tools are already in place, but the government needs to make sure it uses them effectively when needed.
“There are already a lot of elements in place that help us understand that we can respond to this more quickly,” said Dr. Andrew Pekosz, a professor at the Johns Hopkins Bloomberg School of Public Health. “But as always, it's about the efficiency of our responses, right? We know what we can do. We just need to be able to do it effectively.”
The recent infection in a Michigan dairy worker is no surprise, according to experts and the government. The CDC said Wednesday that similar cases in humans could be identified because high levels of the virus have been found in the raw milk of infected cows.
Millions of vaccine doses
The U.S. government currently has two vaccine virus candidates that it believes are well-matched to H5N1. These are weakened versions of a virus that trigger a protective immune response in the body and can be used to make vaccines.
Both candidates are already available to manufacturers, according to the CDC. The government began manufacturing 4.8 million doses of these vaccines last week in case of need, the HHS confirmed.
Pekosz called those doses a “first line of defense in case there is actual human-to-human transmission.” He said that number is enough to contain an early-stage outbreak, which could include vaccinating farmworkers and some health care workers.
However, he stressed that far more resources would be needed for the more than 300 million people in the United States if the virus spreads on a large scale among humans.
“Five million won’t get us very far. This is just a quick start,” said Pekosz.
According to NBC News, U.S. health officials said on May 1 that the government could deliver more than 100 million doses of bird flu vaccine for humans within three to four months if needed.
Specifically, two doses of the vaccine are required, meaning 100 million doses are only enough for 50 million people. This means that the US would need about 600 million doses if it wanted to vaccinate the entire population.
The government is facing a difficult decision about how many vaccines to prepare, especially since production takes several months.
“Either too little or too much. For example, if you prepare too much food, a lot of it will be wasted,” said Dr. Peter Chin-Hong, an infectious disease physician at UCSF Health. “That's really the big problem now with a vaccine when there's a potential threat. It's the high cost and the high risks.”
Chin-Hong said post-Covid misinformation and vaccine skepticism made that decision all the more difficult, but he believes you can “never invest too much in preparing for potential pandemics,” especially at a time when climate change, population growth and other factors are making them increasingly likely.
The Food and Drug Administration would have to approve bird flu vaccines before they go on the market, but Pekosz said that would likely be a “quick process” because the FDA is used to approving seasonal flu vaccines that are made using the same manufacturing process as bird flu shots.
Possible mRNA vaccinations
U.S. health officials are also in talks with mRNA vaccine makers about possible bird flu shots for humans. Few details have been released about those negotiations, but the Health Department said a final announcement is expected soon.
Unlike traditional flu shots, mRNA works by teaching cells to produce a harmless part of a virus that triggers an immune response against certain diseases. It is the same technology that both Pfizer And Modern used in their Covid vaccines.
Chin-Hong said mRNA vaccines could be updated more quickly to match the strains of bird flu currently circulating. But he said these vaccines come with their own challenges, such as needing to be stored at extremely cold temperatures.
In a statement to CNBC, Moderna confirmed that it is in negotiations with the government about its experimental pandemic flu vaccine, mRNA-1018, which targets the exact strain of the virus responsible for the outbreak in dairy cows.
The biotechnology company began testing this vaccine last summer as part of an early- to mid-stage study.
Pfizer declined to confirm negotiations with the government. The company said it was continuing to monitor the spread of H5N1 and was testing its mRNA-based vaccine candidates against pandemic influenza in an early trial.
Virus monitoring and treatments
CDC and its partners, including state and local health departments, use several surveillance systems to monitor seasonal flu and other illnesses. They also have special methods for detecting and monitoring new flu viruses.
Seasonal flu spreads primarily among humans, with predictable peaks throughout the year, while avian flu spreads primarily among wild birds and other animals.
The CDC said it is watching for the H5N1 virus spreading to or among people in areas where the virus has been detected in animals or people. So far, the agency has found “no evidence of unusual flu activity in people,” including H5N1, according to an update on the agency's website last week.
The CDC also conducts ongoing analyses of seasonal and emerging flu viruses to identify genetic changes that might make the viruses more severe in humans, spread more easily between people, or be less sensitive to vaccines and medications.
Although there is widespread testing at the federal, state and local levels, it is far more difficult for the average person to get tested for bird flu and receive a diagnosis than it is for Covid, Chin-Hong said. That is “the big obstacle, especially in the populations that are being affected now,” he said.
Chin-Hong is referring to farmworkers, many of whom are immigrants, who may have difficulty navigating the U.S. health care system due to language barriers and lack of access to health care.
If people do contract the virus, there are some FDA-approved antiviral drugs for seasonal flu that can also be used for bird flu. These include Tamiflu, a prescription oral medication that should be taken within 48 hours of symptoms onset.
A worker on a Texas dairy farm who was diagnosed with bird flu in March was treated with an antiviral drug and recovered, a CDC report said.
However, Pekosz said that antiviral drugs available in national stockpiles would likely not be enough for the vast majority of the population, so manufacturers may be asked to increase their supplies.
According to Francesca Torriani, an infectious disease specialist at UC San Diego Health, the average person can protect themselves from bird flu by avoiding contact with live or dead animals that may be infected, such as livestock or chickens.
People who have to come into contact with these animals should wear appropriate masks and eye protection and wash their hands afterwards.
Torriani added that pasteurized milk and cheese are probably safer to consume than raw milk products because the pasteurization process kills harmful bacteria.
