Bird-flu testing, vaccines and treatments: 5 things you need to know now

By Eleanor Laise

Health officials are ramping up their response to H5N1 - but this is not COVID 2.0, experts say

The race to contain the bird flu kicked into a higher gear this week, as federal and state officials announced new measures designed to ensure the multistate outbreak among dairy cattle doesn't become a flu pandemic.

Public-health officials in recent days have unveiled more detailed plans to ensure availability of effective vaccines and treatments, step up scrutiny of dairy products, and other measures. The Biomedical Advanced Research and Development Authority, an office within the U.S. Department of Health and Human Services, earlier this week released a pandemic-flu strategy - outlining steps such as boosting testing speed and access and encouraging the development of vaccines that can quickly tackle new virus strains. The Food and Drug Administration, meanwhile, this week announced expanded efforts to test dairy products for H5N1, the bird-flu strain currently circulating in dairy cattle.

Those steps come as bird flu affects a growing number of dairy herds. The virus was confirmed this week in seven additional herds in three states -Colorado, Idaho and Iowa - bringing the total to well over 100 herds in a dozen states, according to the U.S. Department of Agriculture. Three U.S. human bird-flu cases have been reported in recent months, all of them tied to dairy-cow exposure.

While H5N1 has been known to circulate among wild birds for decades, infectious-disease experts have raised alarms about its more recent spread among a growing number of mammal species - and particularly dairy cows that have constant contact with humans. Every time an avian virus infects a mammal, it has the opportunity to evolve and become even better at infecting mammals, said Andrew Pekosz, a professor in the department of molecular microbiology and immunology at Johns Hopkins Bloomberg School of Public Health. Each time, "the virus rolls the dice and may come up double sixes in terms of acquiring those mutations that would make it adapt to a new host" and transmit more easily, Pekosz said.

Although the risk to the general public remains low, according to the Centers for Disease Control and Prevention, it's clear that public-health officials are more vigilant than ever. Here's what you need to know about the current state of H5N1 and testing, vaccines and treatments for the disease - and the steps you can take to protect yourself.

1. This is not a COVID rerun

First, the good news: In some ways, we're better off than we were at the start of the COVID-19 pandemic, infectious-disease experts say.

Unlike the onset of COVID-19, H5N1 is not new to us - public-health officials have been tracking and studying it for decades. The federal government already has some vaccines on hand that are well matched to the currently circulating strain, and available flu antivirals such as Tamiflu are thought to be effective against H5N1.

Now for the bad news: The U.S. is still not as prepared as it should be for a potential pandemic, some experts say, as the H5N1 response relies partly on the voluntary efforts of dairy farms to help monitor and contain the spread of the virus. More than 60% of farms continued to move animals off the farm after the onset of clinical signs of bird flu, according to a recent USDA report, raising concerns about disease transmission.

Globally, the death rate among people with H5N1 has also been far higher than for those with COVID. Of the nearly 900 human cases of H5N1 tracked worldwide between 2003 and May of this year, 52% were fatal, according to the World Health Organization.

But the H5N1 fatality rate may not be quite as frightening as it sounds, Pekosz said. It's easier to track the more severe cases - those that result in hospitalizations and deaths - while milder infections may be missed, leading to an underestimate of the number of cases, he said. Even so, Pekosz noted, "I'm sure the virus has higher mortality rates than seasonal flu."

2. Testing faces obstacles

The people who are currently most exposed to H5N1 - dairy workers - can also be challenging to test and monitor, public-health experts say. More than 40% of dairy workers were uninsured as of 2015, according to a USDA study, and many are undocumented. On top of the lack of health coverage, language barriers and concerns about engaging with health officials may put some distance between these workers and health services, according to health-policy-research nonprofit KFF.

Broader availability of bird-flu tests may also be needed, some experts say. Currently, the only authorized test that can specifically identify H5N1 is a CDC test that is available at more than 100 labs nationwide, according to the FDA. Many other widely used flu tests can detect influenza A, a broad category that includes H5N1 as well as some seasonal flu. If one of those tests turns up a suspected bird-flu case, then the CDC's test is needed to determine whether it's H5N1.

While there's currently plenty of testing capacity, if the virus adapts and begins to transmit more easily, having additional tests available would be "incredibly helpful," said Kelly Wroblewski, director of infectious-disease programs at the Association of Public Health Laboratories.

The FDA is working with test developers who may be interested in developing bird-flu tests, an agency official told MarketWatch, but so far the FDA has not received regulatory submissions for any additional manufacturers' tests that could identify H5N1.

Nearly 700 people have been monitored because of their exposure to infected cows, according to the CDC, and more than 50 people have been tested because they developed symptoms. Under a broader flu-testing protocol, however, more than 30,000 human samples have also been tested since early March, the CDC said, and none of those were found to be tied to H5N1.

"CDC believes that the current testing guidance and supplies are appropriate for the situation now," a CDC spokesperson told MarketWatch. There are currently nearly 1 million H5-specific CDC tests, the spokesperson said, and 1 million more will be available in the coming months.

On top of testing for new cases, more testing for bird-flu antibodies is also needed, Pekosz said. Many people who were exposed to the virus early on may have no current signs but likely have antibodies that could indicate prior infections. Such testing is moving forward in at least one state, Michigan, with help from the CDC, health officials said this week.

3. We have wastewater surveillance to help detect flu - but it may not help much

The CDC now has data that show the levels of influenza A viruses in wastewater from regions across the country and can compare them to levels at the same sites during the 2023-2024 flu season. But the wastewater-monitoring methods don't distinguish among influenza A subtypes or between human and animal sources.

"It's still a relatively new tool, and we don't have a lot of baseline data to identify true signals from noise," Wroblewski said. Some of the signals seen so far, she said, turned out to be tied to the dumping of milk or cleaning out of trucks that were carrying dairy cattle.

While there's "tremendous potential" for this type of surveillance, Wroblewski said, "we're still learning how to use it most effectively and most efficiently."

4. Some experts say vaccination should start now - but government officials aren't making any promises

The Administration for Strategic Preparedness and Response, an agency within the Department of Health and Human Services, is working with the FDA to label hundreds of thousands of existing doses of vaccine and filling another 4.8 million doses of the same vaccine, which is "well matched to the circulating H5N1 strain," an ASPR spokesperson told MarketWatch. Those additional doses will be completed this summer, the spokesperson said.

If we have shots that are considered safe and effective, it makes sense to start putting them in arms, some experts say. "Immunizing dairy-farm workers would be a great use of the existing stockpile right now," Pekosz said, adding that "vaccination can be very targeted" to protect the people most at risk. But communication would be key, he noted: "We don't want these hollow victories - like we'll give vaccines to all these dairy-farm workers, yet no one shows up to take it."

No vaccine campaign is imminent, the ASPR spokesperson said, as the risk to people remains low. The CDC spokesperson said the agency is involved in "early, ongoing discussions" of H5N1 vaccination and where and when it might be appropriate, but the virus is still "largely an agricultural issue affecting animal health." If the risk assessment changes, the spokesperson said, that could prompt additional steps to provide vaccines either to specific groups or the public more broadly.

If the virus evolves and circulates among humans, however, the existing vaccines may not be such a good match. The Biomedical Advanced Research and Development Authority is working to add an mRNA platform for flu vaccines - which could potentially be integrated into its national vaccine-stockpile program, the ASPR spokesperson said - and accelerating its clinical-trial efforts. Moderna Inc.'s stock (MRNA) climbed late last month after a report that BARDA was nearing a deal to fund a late-stage trial of its experimental bird-flu vaccine. The ASPR spokesperson said Thursday that "specifics of ongoing contract discussions cannot be released at this time."

5. You can take steps to protect yourself

One clear and simple way to lower your risk: Don't drink raw milk. Pasteurization kills off harmful bacteria and viruses by heating milk to a specific temperature for a set period of time.

Some experts would still like to see more testing to ensure the milk supply's safety. "We know pasteurization works, but pasteurization is not sterilization and should not be our only defense," Pekosz said.

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06-28-24 1402ET

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