H5N1 Bird Flu Virus Threat: Urgency and Challenges

The bird flu outbreak among dairy cattle has, as of now, affected only three farmworkers in the United States, according to public health authorities. These individuals experienced mostly mild symptoms. Nevertheless, there is no guarantee that the virus, known as H5N1, will maintain its benign nature if it starts to spread within human populations. Evidence from the animal kingdom and data from various parts of the world suggest the opposite. Some dairy cows failed to recover from H5N1, leading to their death or slaughter. Terns that were infected appeared disoriented and unable to fly. Elephant seal pups showed signs of difficulty in breathing and developed tremors after contracting the virus. Infected cats lost their vision and exhibited a tendency to walk in circles, with two-thirds of them ultimately succumbing to the illness.

“Anice Lowen, a virologist at Emory University, strongly emphasized the urgency of the situation, stating that there is no room for complacency. She highlighted the highly pathogenic nature of the H5N1 influenza virus and the need for heightened concern, especially if it is crossing over to affect humans.

What Shocked?

In an eye-opening report published on Wednesday, it was revealed that ferrets, when experimentally inoculated with the virus through their eyes (which is the presumed route of infection in U.S. farmworkers), experienced rapid spread of the virus to their airways, lungs, stomach, and even their brains.

Furthermore, studies involving mice fed contaminated milk have also shown similar patterns. These findings suggest that the virus may pose a significant threat regardless of whether it enters the body through the eyes or the digestive system.

H5N1 has demonstrated its ability to infect a wide range of hosts, including wild birds, poultry, mice, bears, cats, and sea lions. Since its discovery in 1996 in Hong Kong, the virus has infected nearly 900 people, highlighting the urgency of the situation.”

An older strain of the virus that originated in Asia has caused fatal outcomes for approximately half of those who were infected.

One in China Died

Out of the 15 individuals affected by the current strain circulating among cattle, one person in China passed away while another required hospitalization. In Chile and Ecuador, two patients experienced severe symptoms. As for Americans, one person was infected last year, and three have been infected in the most recent outbreak, all of whom have shown signs of improvement.

Notably, none of the bird flu virus variants have shown efficient person-to-person transmission. However, virologist and bird flu expert Yoshihiro Kawaoka from the University of Wisconsin-Madison cautioned that this does not guarantee that H5N1 will not develop this capability. Dr. Kawaoka emphasized that there are clear indications of the virus altering its characteristics, as evidenced by the unanticipated outbreaks in cows and the unexpected appearances of symptoms such as conjunctivitis (pink eye) and the virus in mammary glands of cattle and even non-lactating mice.

The concern is that as the H5N1 virus continues to infect animals and evolve, it might acquire the genetic changes necessary to efficiently spread among humans, potentially leading to another widespread outbreak. According to Erin Sorrell, a virologist and senior scholar at the Johns Hopkins Center for Health Security, the incubation period for the flu is typically two to four days. If a human-to-human version were to emerge, it could spread rapidly before cases are even detected, making it difficult to control. Once the virus is in the general public, it may be too late to effectively contain it.

Children at Risk

It’s important to note that the severity of flu can vary, with older adults and young children being most at risk. The level of illness also depends on factors such as the amount of virus a person is exposed to, the duration of exposure, the route of transmission, as well as individual genetic background and overall health.

The bird flu virus poses a serious threat to global health, as infected individuals often experience fever and respiratory symptoms that can quickly progress to pneumonia or even death. In the event of the virus adapting to humans, the world would require billions of doses of vaccines and antivirals to mitigate the potential devastating consequences.

Need to be administered within 48 hours

Currently, the federal stockpile contains four types of flu antivirals, but they need to be administered within 48 hours of symptom onset to be effective. However, a recent review found insufficient evidence to determine the effectiveness of three out of the four drugs, including the widely used oseltamivir (Tamiflu). Some new strains of the H5N1 virus have developed mutations that render the virus resistant to oseltamivir and two other drugs, but fortunately, these changes have not spread widely among animal populations. There have been no observed mutations against the fourth drug, baloxavir, but the stockpile only contains a limited supply of a few hundred thousand doses, according to David Boucher, the infectious disease director of the federal Administration for Strategic Preparedness and Response.

While vaccines offer a more promising solution to preventing a pandemic, it is unlikely that a sufficient number of doses will be available for several months at the very least. Even if global production of seasonal flu vaccines were entirely dedicated to H5N1 vaccines, the resulting number of doses manufactured would be inadequate for less than two billion people, assuming each person requires two doses.

According to New York Times, The United States has a national stockpile containing a large number of vaccine doses that could be administered to people at risk, including children. Companies working with the government could produce over 100 million doses within the first 130 days, according to Dr. Boucher. Recently, officials announced that they have prepared 4.8 million doses that could be packaged without disrupting the production of seasonal flu vaccines. However, the effectiveness of these plans depends on the behavior of the virus.

Since the initial appearance of H5N1, it has evolved into various forms, leading scientists to develop a library of 40 “candidate vaccine viruses” to match these different forms. Keeping these candidate vaccines ready can save valuable time, as creating a new candidate virus can take up to three months, as highlighted by Todd Davis, a virologist at the Centers for Disease Control and Prevention.

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Spreading among humans

experts have discussed the possibility of the flu virus changing significantly to spread among humans. It highlights the challenges in producing traditional flu vaccines, which are typically grown in eggs or mammalian cells. It also provides an example of a past situation where delays in vaccine distribution occurred due to the virus evolving into a poor match for the wild virus. Additionally, it mentions the existence of a cell-based H5N1 vaccine that has already been approved by the FDA.

During a pandemic, CSL has the potential to produce 150 million doses of a candidate vaccine within six months to supply to the United States, as stated by the company’s executive director, Marc Lacey. Additionally, CSL has contracts with 19 other countries for vaccine distribution. Despite this substantial supply, 150 million doses would only cover approximately 20% of the American population.

Federal officials are considering mRNA bird flu vaccines, which can be rapidly developed, as evidenced by the Covid pandemic, for the protection of both cattle and humans. Dr. Hensley’s team is currently conducting trials on an mRNA vaccine for cattle.

Although experts acknowledge that vaccinating cows would reduce the risk to farm workers and other cows, and limit the virus’s ability to spread and mutate, concerns about trade implications have delayed the deployment of such vaccines. Some countries prohibit imports of products from vaccinated birds and animals, posing a barrier to immunizing cows.

Even though farm workers face potential risks, federal officials have been hesitant to vaccinate them, citing the current low risk level.