Pathfinder
Editor, Senior Moderator
Review Published: 24 September 2024
The global H5N1 influenza panzootic in mammals
Thomas Peacock, Louise Moncla, Gytis Dudas, David VanInsberghe, Ksenia Sukhova, James O. Lloyd-Smith, Michael Worobey, Anice C. Lowen & Martha I. Nelson
...
Prospects for the Future
Stocks of H5 vaccine that are antigenically related to circulating 2.3.4.4b viruses are available
and could be produced at scale using mRNA platforms if H5N1 begins spreading in humans140.
The severity of a future H5N1 pandemic remains unclear. Recent human infections with H5N1
2.3.4.4b viruses have a substantially lower case fatality rate compared to prior H5N1 outbreaks
in Asia, where half of people with reported infections died14. The milder symptoms in US
farmers have been attributed to the route of infection through the eye65 and absence of viral
pneumonia in the lung. Whether B3.13 viruses cause less severe disease in humans or whether
mild cases are simply under-detected in Asia is unclear due to case ascertainment bias142.
Older people appear to have partial immunity to H5N1 due to childhood exposure (“imprinting”)
to seasonal H1N1 and H2N2 viruses, whereas younger people born since the 1968 H3N2
pandemic may be more susceptible to severe disease in a H5N1 pandemic143. Some degree of
cross-reactivity between H5N1 and the avian-origin N1 neuraminidase that has circulated in
humans since the 2009 pandemic may also provide partial protection144. At the same time,
symptoms and disease severity could change if B3.13 viruses further adapt to infect the
respiratory tract.
Going forward, we know more about H5N1’s global distribution (Figure 1), non-human
host range (Figure 2), and genetic diversity (Figure 3) than virtually any other zoonotic
pathogen. Still, most H5N1 testing is conducted in dead or severely ill animals. One lesson from
the COVID-19 pandemic is that symptomatic cases that result in severe disease are clinically
important, but unobserved subclinical infections can be important in transmission and fuel
epidemics at a population level. The H5N1 panzootic has been defined by powerful visuals of
beaches littered with sea lion carcasses or barns of ill dairy cows wasting away after going off
feed. But what keeps scientists up at night is the possibility of unseen chains of transmission
silently spreading through farm worker barracks, swine barns, or developing countries, evolving
under the radar because testing criteria are narrow, government authorities are feared, or
resources are thin. A second lesson from the COVID-19 pandemic is not to underestimate the
importance of human behavior, culture, and economic context. New technologies like mRNA
vaccines, next-generation sequencing, and CRISPR-Cas diagnostics provide rapid, flexible
tools for outbreak response, but are of little use when they are not allowed on the farm.
...
https://flutrackers.com/forum/forum...panzootic-in-mammals-nature-september-24-2024
The global H5N1 influenza panzootic in mammals
Thomas Peacock, Louise Moncla, Gytis Dudas, David VanInsberghe, Ksenia Sukhova, James O. Lloyd-Smith, Michael Worobey, Anice C. Lowen & Martha I. Nelson
...
Prospects for the Future
Stocks of H5 vaccine that are antigenically related to circulating 2.3.4.4b viruses are available
and could be produced at scale using mRNA platforms if H5N1 begins spreading in humans140.
The severity of a future H5N1 pandemic remains unclear. Recent human infections with H5N1
2.3.4.4b viruses have a substantially lower case fatality rate compared to prior H5N1 outbreaks
in Asia, where half of people with reported infections died14. The milder symptoms in US
farmers have been attributed to the route of infection through the eye65 and absence of viral
pneumonia in the lung. Whether B3.13 viruses cause less severe disease in humans or whether
mild cases are simply under-detected in Asia is unclear due to case ascertainment bias142.
Older people appear to have partial immunity to H5N1 due to childhood exposure (“imprinting”)
to seasonal H1N1 and H2N2 viruses, whereas younger people born since the 1968 H3N2
pandemic may be more susceptible to severe disease in a H5N1 pandemic143. Some degree of
cross-reactivity between H5N1 and the avian-origin N1 neuraminidase that has circulated in
humans since the 2009 pandemic may also provide partial protection144. At the same time,
symptoms and disease severity could change if B3.13 viruses further adapt to infect the
respiratory tract.
Going forward, we know more about H5N1’s global distribution (Figure 1), non-human
host range (Figure 2), and genetic diversity (Figure 3) than virtually any other zoonotic
pathogen. Still, most H5N1 testing is conducted in dead or severely ill animals. One lesson from
the COVID-19 pandemic is that symptomatic cases that result in severe disease are clinically
important, but unobserved subclinical infections can be important in transmission and fuel
epidemics at a population level. The H5N1 panzootic has been defined by powerful visuals of
beaches littered with sea lion carcasses or barns of ill dairy cows wasting away after going off
feed. But what keeps scientists up at night is the possibility of unseen chains of transmission
silently spreading through farm worker barracks, swine barns, or developing countries, evolving
under the radar because testing criteria are narrow, government authorities are feared, or
resources are thin. A second lesson from the COVID-19 pandemic is not to underestimate the
importance of human behavior, culture, and economic context. New technologies like mRNA
vaccines, next-generation sequencing, and CRISPR-Cas diagnostics provide rapid, flexible
tools for outbreak response, but are of little use when they are not allowed on the farm.
...
https://flutrackers.com/forum/forum...panzootic-in-mammals-nature-september-24-2024
