Many mammals, including Spanish minks, Scottish seals, and South American sea lions and dolphins, have recently been found to be infected with H5N1, a highly virulent strain of avian influenza. Bird flu is nothing new. Epidemiologists have studied it for decades. However, with the virus detected in mammals, many are concerned about the virus’ potential to spread to humans and trigger a larger outbreak.
As a global pandemic caused by a virus that appears to come from animals enters its fourth year, it is reasonable to worry about another virus that could upend our lives. H5N1 has infected humans before, but human-to-human transmission has rarely been observed. And while the World Health Organization (WHO) reports that bird flu in humans has a mortality rate of about 56%, many experts believe the mortality rate could be much higher if the virus becomes more contagious. One of the reasons bird flu is so deadly is that it can infect the lower respiratory tract and cause respiratory failure. If it infects the upper respiratory tract and mutates to spread more easily, it will probably cause milder illness. can even cause serious damage. Efforts are therefore underway to develop a vaccine to protect against this type of bird flu.
Bird flu has spread to humans before. In fact, last week a Cambodian girl died of her H5N1 (though not the same strain that sickens birds around the world).
“Every time this happens, we see a spike in these cases. [and] People say says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. But he stressed that H5N1 is likely not an immediate threat to humanity.
Others agree. “I am watching closely as a professional, community member, parent and guardian. [has been] I recently experienced the COVID-19 pandemic, but so far I’m not worried,” says Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security. “This is currently an animal health problem and could theoretically become a human health problem.”
Avian influenza viruses infect birds by attaching to receptors in the respiratory tract. In order for the virus to become a human virus and begin circulating from person to person within the population, it must be able to attach to the human version of this receptor. It hasn’t evolved yet.
“It’s a really dangerous time for birds,” adds Andrew Pavia, director of the Pediatric Infectious Diseases Division at the University of Utah. “But as of today, the risk to humans remains very low. Our concern is what will happen as it becomes more and more circulated.”
Unfortunately, it’s nearly impossible to predict when this jump will occur. “No one knows when the next flu pandemic will hit. It could be tomorrow. [or] It may be years away and we don’t know which virus will be the next pandemic virus,” Osterholm said. “First, I have to say that there is uncertainty, with one exception: a pandemic will occur.”
The United States is somewhat prepared to deal with bird flu. We have a stockpile of egg-based influenza vaccines for the H5N1 strain. Eggs are one of the most popular ways to make flu vaccines. To create it, manufacturers inject killed or weakened virus into fertilized chicken eggs, incubate the eggs for several days while the virus multiplies, and then harvest the virus for use in vaccines.The country has clandestine chicken stockpiles at undisclosed locations across the United States in case an egg-based vaccine needs to be manufactured quickly, such as during a flu pandemic. The reliance on animals highly susceptible to the flu in question may be concerning. Scientific American Poultry facilities should have a high level of biosecurity to avoid contamination with bird flu.
There are alternatives to egg-based vaccines. Since the early 2010s, the U.S. Department of Health and Human Services has partnered with CSL Seqirus, one of the largest flu vaccine makers, to develop vaccines in laboratory cell culture. The anti-pandemic vaccine AUDENZ, which specifically targets the H5N1 subtype, has been approved by the Food and Drug Administration. And while it’s impossible to identify which virus will cause the next pandemic, CSL Seqirus has a library of viruses that can infect humans. The company is constantly searching for candidate vaccine viruses that can be tailored to specific pathogens.
“We use data [for] said Mark Lacy, who leads the Pandemic Preparedness and Response Team at CSL Seqirus. Team members can basically identify specific viruses, use them to create vaccines, and be ready to use the appropriate vaccines should bird flu strains evolve into true pandemic strains that can be transmitted between humans. Lacy said his company hopes to supply 150 million doses to the U.S. government within the first six months after a pandemic is declared. can be done, but we think the potential for scale-up could be greater, especially if multiple manufacturers can help produce it.There are 8 billion people in the world. Therefore, to manufacture sufficient vaccines, scale-up and extensive cooperation across countries are required.
There are also efforts to apply messenger RNA (mRNA) technology, such as that used in some COVID vaccines, to flu vaccines. According to Deborah Fuller, a microbiologist at the University of Washington, these efforts go from developing a universal flu vaccine to only a few subtypes or versions of the virus (like typical seasonal flu vaccines). It extends to creating targeted “multivalent” vaccines. One of the advantages of mRNA technology is the speed of production. Also, the COVID pandemic has increased the infrastructure for mass production. “RNA vaccines can be designed very quickly. [you] We can have vaccines that have already been tested in animal models,” says Fuller.
Scott Hensley, a professor of microbiology at the University of Pennsylvania, is also working on an mRNA flu vaccine. He is part of a research team developing his vaccine for mRNA flu for 20 subtypes, including the H5N1 strain (but not the one currently prevalent in birds).The team recently published its findings Chemistry. Hensley’s lab is currently developing a single-strain vaccine tailored to current avian flu strains and is already testing it in laboratory animals. , emphasizes that it is intended to prevent serious illness and death.
However, even 20 subtype vaccines are expected to provide some degree of protection against new strains. “When we developed [that] The idea of a vaccine was to create something that could induce a certain level of immune memory against all subtypes,” says Hensley. It was not about predicting which strains would cause or which strains would cause it. [would induce] It has some degree of immune memory for all subtypes, limiting illness and death caused by new pandemic strains. “
Vaccines are only part of pandemic preparedness. We also need effective treatments. As Pavia says, the researchers aren’t working from scratch trying to make something like the COVID antiviral drug Paxlovid, and it took him nearly two years to get to market. FDA-approved influenza antivirals, such as Tamiflu, already exist and are critical for reducing deaths during influenza pandemics. Pavia also hopes the U.S. will be able to quickly adapt diagnostic tests to pandemic strains of his influenza.
“We have better tools and knowledge about flu than coronavirus. “But what worries me is our political capacity to respond. [increase] Be aware and continue your preparation efforts. And if things start to accelerate, we need a concerted, non-political effort to move quickly and effectively. “
