As H5N1 highly pathogenic avian influenza (AI) spreads for over a year, mainly among migratory birds, chickens, ducks, and dairy cattle in the United States, a plan is underway to directly vaccinate birds.
Last month, a case of death from H5N1 infection in the U.S. marked the first such instance, increasing fears of a pandemic, prompting the government's response.
Zoetis, a U.S. animal health company, announced on the 14th (local time) that it received conditional approval from the U.S. Department of Agriculture (USDA) for its avian influenza vaccine.
Conditional approval is a system that allows temporary use of medications that demonstrate safety and similar efficacy when no emergency medications are available. If preventive effects are proven within a year, formal approval can be obtained to proceed with sales.
Zoetis is the world's leading company in the animal medicine sector, having spun off from Pfizer's animal health division. It sells over 300 types of products, including livestock vaccines, anti-inflammatory drugs, painkillers, feeds, and nutritional supplements, to more than 100 countries worldwide. In 2020, it developed a vaccine for the novel coronavirus disease (COVID-19) for animals and administered it to animals at zoos.
The company first developed a vaccine when H5N1 avian influenza broke out in Southeast Asia in 2002. Following the identification of high pathogenic avian influenza (HPAI) in the U.S. in early 2022, Zoetis immediately began updating its existing avian influenza vaccine.
Mahesh Kumar, senior vice president of global biopharmaceutical research and development at Zoetis, noted, "The vaccine that the USDA has conditionally approved this time is the one we are currently updating," adding, "Clinical trials are necessary to determine if its efficacy against the H5N1 variant is as high as the previous HPAI vaccine."
H5N1 is a variant of HPAI that is particularly lethal to poultry such as chickens and turkeys. It is named H5N1 because the surface proteins hemagglutinin (HA) and neuraminidase (NA) are type 5 and type 1, respectively. HA functions as a key for the virus to bind to human respiratory cells, while NA enables the virus to break through the cells after replication.
The spreading H5N1 virus among poultry and wild birds in the U.S. has increased fears as it has begun to infect humans. In the past year alone, there have been 66 cases of human infection with H5N1. Last month, the first death among those infected was reported. Concerns have grown that the already global spread of H5N1 through migratory birds could lead to another global pandemic following COVID-19.
The Animal and Plant Health Inspection Service under the U.S. Department of Agriculture reported that 146 avian flocks have been infected with avian influenza in the past month, affecting over 20.5 million birds. Since the spread of avian influenza began in February 2022, it is estimated that over 150 million birds have been impacted.
As avian influenza continues to spread, voices criticizing the focus on culling are rising. Until now, major countries, including South Korea and the U.S., have culled chickens and ducks when avian influenza was spreading, but issues of inhumanity and low efficiency in biosecurity have been raised.
In South Korea, as concerns about excessive culling grew, the Ministry of Agriculture, Food and Rural Affairs narrowed the culling target radius from 3 km from infected farms to 1 km in 2021. Despite these measures, resistance continued. It is problematic to cull all non-infected individuals just because they are within the radius of infected farms.
There are also differences in economic aspects. In the case of culling, expenses for equipment, personnel, and compensation can exceed 10,000 won per bird, while vaccines only cost around 200 won.
The U.S. government is recently exploring alternative responses instead of culling. Kevin Hassett, Director General of the White House Council of Economic Advisers, said on the 16th to CNN, "I will present a plan to eliminate the virus that does not require culling chickens to President Trump," noting, "We are contemplating that method utilizing our top scientists and life science technologies."
Meanwhile, the development of influenza vaccines for humans is also actively underway. Companies such as Pfizer, Moderna, Novavax, and CureVac are working on it. In particular, Moderna received $176 million (1.24 trillion won) in funding from the U.S. government last July to develop an H5N1 vaccine.
In South Korea, movements to develop H5N1 vaccines are accelerating. Biotech Vaxdime, Yonsei University College of Medicine, and Korea Vaccine signed a rapid development consortium agreement on the 4th.