By Julie Steenhuysen and Jennifer Rigby
CHICAGO/LONDON (Reuters) – Scientists tracking the spread of bird flu are increasingly concerned that gaps in surveillance could leave them several steps behind a new pandemic, Reuters interviews with more than a dozen leading disease experts showed.
Many have been monitoring the new H5N1 subtype of avian influenza in migratory birds since 2020. But the virus’s spread to 129 dairy cattle herds in 12 U.S. states suggests a shift that could make it more likely to spread between humans. The infection has also been found in other mammals, from alpacas to domestic cats.
“It feels like a pandemic unfolding in slow motion,” said Scott Hensley, a professor of microbiology at the University of Pennsylvania. “Right now, the threat is very low… but that could change in the blink of an eye.”
The earlier the warning of human transmission, the sooner global health officials can take steps to protect people by launching vaccine development, widespread testing and containment measures.
Federal monitoring of U.S. dairy cows is currently limited to testing herds before they cross state lines. Government health officials and pandemic influenza experts told Reuters that the state’s testing efforts are inconsistent, while testing of people exposed to sick livestock is minimal.
“You have to know what farms are positive, how many cows are positive, how widespread the virus is, how long these cows remain infectious, and the exact transmission route,” said Dutch influenza virologist Ron Fouchier of Erasmus Medical Centre. In Rotterdam.
Human monitoring is “very limited,” said Dr. Jane Marrazzo, director of the US National Institute of Allergy and Infectious Diseases.
Marrazzo described the US Centers for Disease Control and Prevention’s Human Influenza Surveillance Network as a “passive reporting and presentation mechanism.” She added that the USDA is more proactive in testing cows, but does not announce which farms are affected.
Several experts said that different approaches by animal and human health agencies could hamper a faster response.
“If you’re designing the system from scratch, you’re going to have one agency,” said Gigi Gronvall, a biosecurity expert at the Johns Hopkins Center for Health Security. “And this isn’t the only example where we have environmental or animal problems that cause human problems.”
A USDA spokesperson said the agency is working “around the clock” with the Centers for Disease Control and Prevention and other partners on a “whole-of-government response,” adding that ongoing research shows that “the U.S. food supply remains safe, and sick cows generally recover after a few days.” “Weeks.” The risk to human health remains low.
“The USDA and state and local health departments across the country have been preparing for the emergence of a new influenza virus for nearly two decades and are constantly monitoring even the smallest changes in the virus,” the CDC said in a statement.
“Warning note”
Some pandemics, including COVID-19, come without warning. In the last influenza pandemic, caused by the H1N1 virus in 2009, the virus and its precursors spread among animals for the first time in several years, Hensley said, but more monitoring would have helped health authorities prepare.
Three people in the United States have tested positive for H5N1 avian influenza since late March after coming into contact with cows, and have developed mild symptoms. One person in Mexico was infected with a separate strain of H5 virus that had never been seen in humans, and there was no known exposure to animals. Other cases have been reported in India, China and Australia, caused by different strains.
The World Health Organization says the risk to humans from H5N1 is low because there is no evidence of human-to-human transmission. Some tools are available if that changes, including limited supplies of existing H5N1 vaccine and antiviral drugs such as Tamiflu.
The head of the influenza division at the UN agency, Wen Qingzhang, said that there are mechanisms to launch large-scale production of tests, treatments and vaccines, if necessary.
Other experts said there is enough concern to start preparing for a potential human-to-human spread, although the triggers for taking action vary depending on the role played in the response, said Richard Hatchett, CEO of the Coalition for Epidemic Preparedness Innovations (CEPI). His organization worked early on to fund the development of a coronavirus vaccine, and is now in talks with research partners about the H5N1 virus.
The Coalition for Epidemic Preparedness Innovations (CEPI) aims to create a library of early vaccines for pathogens with potential pandemic potential. This would help drugmakers begin mass production and distribute doses when needed within 100 days of an outbreak.
Some countries are taking steps to protect people from the H5N1 virus. The United States and Europe are working to secure doses of “pre-pandemic” flu vaccine that could be used for at-risk groups, including farm or laboratory workers. Finland is expected to become the first country to vaccinate fur and poultry farm workers, as well as animal health response workers.
Expanding access to vaccines is also complicated, said WHO’s Zhang. Potential flu vaccine manufacturers produce seasonal flu vaccines and can’t produce both at the same time, she added.
Because most influenza vaccines are made using virus grown in eggs, it can take up to six months to produce pandemic vaccines. The United States is in talks with accident (NASDAQ:) to use faster mRNA technology in pandemic influenza vaccines.
The experts all acknowledged the need to balance acting quickly to avoid the threat and overreacting.
“We want to sound the alarm, without saying the world is about to end,” said Wendy Barclay, a virologist at University College London who researches bird flu for the UK’s Health Security Agency.