The scientific community is increasingly concerned about gaps in monitoring avian influenza pathogens that could cause the world to “fall several steps behind” in the face of a new pandemic.
Many researchers have been tracking a new strain of the H5N1 influenza virus in migratory birds since 2020. However, they believe that the spread of the virus to 129 dairy herds across 12 U.S. states signals significant changes. These changes could bring the virus closer to the potential for human transmission.
“It resembles a pandemic unfolding slowly. Currently, the threat is quite low, but that could change in an instant, similar to Covid-19,” said Scott Hensley, a professor of microbiology at the University of Pennsylvania.
For instance, federal surveillance of dairy cows in the U.S. is currently limited to testing herds before they are transported across administrative borders. Testing between regions is also inconsistent. Surveillance of contact with livestock is very limited, according to officials and pandemic experts.
“We need to identify which farms have positive flu cases, how many cases, the extent of the virus spread, how long a cow has been sick, and the precise mode of transmission,” remarked Ron Fouchier, a virologist at the Erasmus Medical Center in Rotterdam.
Similarly, Dr. Jeanne Marrazzo, director of the National Institute of Allergy and Infectious Diseases, stated that clinical surveillance for the virus is “very, very limited.” She noted that the screening network of the Centers for Disease Control and Prevention (CDC) is quite passive, suggesting that the U.S. Department of Agriculture is proactive in testing herds but does not publicly disclose which farms are affected. Some experts indicate that animal health and human health agencies respond differently to the situation, which could hinder the overall response.
Free-range chickens at Hilliker’s Ranch Fresh Eggs Farm, California, USA, April 2022. (Photo: Reuters).
In reality, some pandemics, including Covid-19, emerged with very few warning signs. In the last major flu pandemic (H1N1 in 2009), the virus initially spread in animal populations for several years. This is similar to the current behavior of H5N1.
The U.S. has reported three positive tests for H5N1 flu since late March. The patients had contact with infected cattle and exhibited mild symptoms. Mexico reported a case of a unique H5 strain never before seen in humans. This patient had no contact with animals. Isolated cases have also emerged in India, China, and Australia, caused by different strains.
The World Health Organization (WHO) stated that the risk of H5N1 infection in humans remains low, with no evidence of community transmission of the virus. There is a vaccine available (albeit in limited quantities) and Tamiflu for treatment. Many pharmaceutical companies already have large-scale production lines for flu testing kits, treatment methods, and vaccines if needed, said Wenqing Zhang, head of the WHO’s flu response unit.
According to Richard Hatchett, CEO of the Coalition for Epidemic Preparedness Innovations (CEPI), the risk is significant enough for countries to prepare for scenarios where the avian flu virus spreads to humans. The coalition acted early in developing the Covid-19 vaccine and is negotiating with partners to research the H5N1 vaccine. CEPI aims to create a prototype vaccine library for pathogens that could cause pandemics, enabling pharmaceutical companies to begin large-scale production and distribution of necessary vaccines within 100 days of an outbreak.
Countries Prepared to Act
Some countries are taking initial steps to protect their populations from the risk of H5N1 infection. The U.S. and Europe are stockpiling “pandemic preparedness” vaccines that could be used for high-risk groups, including farm workers or laboratory specialists. Finland has become the first country to vaccinate against avian influenza.
However, expanding vaccination campaigns is quite complex. Manufacturers of “pandemic preparedness” vaccines still need to produce seasonal flu vaccines. However, they cannot handle both vaccines simultaneously. Most flu vaccines are produced using virus grown in eggs, which requires six months for development.
The U.S. is negotiating with Moderna to utilize mRNA technology, which would allow for quicker development of pandemic preparedness vaccines.
All experts agree that swift action is needed to prevent the threat, but without overreacting and causing community panic.
“We want to issue a cautious warning, but without creating a sense of impending doom within the community,” said Wendy Barclay, a virology expert at Imperial College London and an advisor to the UK’s Health Security Agency on avian influenza.
