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Bird flu pandemic may be 'unfolding in slow motion,' scientists warn
(HTM) Source
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Scientists tracking the spread of bird flu are increasingly concerned
that gaps in surveillance may keep them several steps behind a new
pandemic, according to Reuters interviews with more than a dozen
leading disease experts.
Many of them have been monitoring the new subtype of H5N1 avian flu in
migratory birds since 2020. But the spread of the virus to 129 dairy
herds in 12 U.S. states signals a change that could bring it closer to
becoming transmissible between humans. Infections also have been found
in other mammals, from alpacas to house cats.
"It almost seems like a pandemic unfolding in slow motion," said Scott
Hensley, a professor of microbiology at the University of
Pennsylvania. "Right now, the threat is pretty low … but that could
change in a heartbeat."
The earlier the warning of a jump to humans, the sooner global health
officials can take steps to protect people by launching vaccine
development, wide-scale testing and containment measures.
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Federal surveillance of U.S. dairy cows is currently limited to
testing herds before they cross state lines. State testing efforts are
inconsistent, while testing of people exposed to sick cattle is scant,
government health officials and pandemic flu experts told Reuters.
"You need to know which are the positive farms, how many of the cows
are positive, how well the virus spreads, how long do these cows
remain infectious, the exact transmission route," said Dutch flu
virologist Ron Fouchier of the Erasmus Medical Center in Rotterdam.
Dr. Jeanne Marrazzo, director of the U.S. National Institute of
Allergy and Infectious Diseases, said surveillance for humans is
"very, very limited."
1:36 Infectious disease physicians issue bird flu guidance for Canada
Marrazzo described the U.S. Centers for Disease Control and
Prevention's human flu surveillance network as "really a passive
reporting, passive presentation mechanism." The U.S. Department of
Agriculture is more proactive in testing cows, but does not make
public which farms are affected, she said.
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Several experts said differing approaches from animal and human health
agencies could hamper a quicker response.
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"If you were designing the system from scratch, you would have one
agency," said Gigi Gronvall, a biosecurity expert at the Johns Hopkins
Center for Health Security. "This is not 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
CDC and other partners in a "whole-of-government response," adding
that ongoing research shows "America's food supply remains safe, sick
cows generally recover after a few weeks, and the risk to human health
remains low."
The CDC in a statement said, "USDA, and state and local health
departments across the country have been preparing for the emergence
of a novel influenza virus for nearly two decades and continually
monitor for even the smallest changes in the virus."
Some pandemics, including COVID-19, arrive with little warning. In the
last flu pandemic, caused by H1N1 in 2009, the virus and its
predecessors had first spread among animals for several years, Hensley
said, but more surveillance would have helped health authorities
prepare.
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Three people in the U.S. have tested positive for H5N1 avian flu since
late March after contact with cows, experiencing mild symptoms. One
person in Mexico was infected with a separate H5 strain not previously
seen in humans, and with no known exposure to animals. Other cases
were reported in India, China and Australia, caused by different
strains.
The World Health Organization says H5N1's risk to humans is low
because there is no evidence of human transmission. Some tools are
available if that changes, including limited amounts of existing H5N1
vaccine and antiviral medications like Tamiflu.
There are mechanisms to launch larger-scale production of tests,
treatments and vaccines if needed, said the U.N. agency's head of flu,
Wenqing Zhang.
Other experts said there is sufficient concern to start preparing for
a potential spread in humans, although triggers for taking action
differ depending on the role played in the response, said Richard
Hatchett, chief executive of the Coalition for Epidemic Preparedness
Innovations (CEPI). His organization acted early on funding COVID
vaccine development and is now in talks with research partners about
H5N1.
3:54 Canada is testing retail milk for bird flu
CEPI aims to create a library of prototype vaccines for pathogens with
pandemic potential. This would help drugmakers initiate large-scale
production and distribute shots where necessary within 100 days of an
outbreak.
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Some countries are taking steps to protect people against H5N1. The
United States and Europe are securing doses of "pre-pandemic" flu
vaccine that could be used for high-risk groups, including farm or lab
workers. Finland is expected to become the first country to inoculate
fur and poultry farm workers, as well as animal health response
workers.
Expanding vaccine access is also complex, said the WHO's Zhang.
Manufacturers of potential pandemic flu vaccines make seasonal flu
shots and cannot produce both at once, she said.
Since most flu vaccines are made using virus-grown-in eggs, it could
take up to six months to produce pandemic shots. The U.S. is in talks
with Moderna MRNA.O to use their faster mRNA technology for pandemic
flu shots.
The experts all acknowledged a need to balance acting quickly to avert
a threat versus overreacting.
"We want to sound a note of caution," said Wendy Barclay, a virologist
at Imperial College London who also advises the UK Health Security
Agency on avian flu, "without saying the world is about to end."
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