# 7498
Over the past several months we’ve watched a steady procession of research published on China’s newly emerging H7N9 virus, and which each report, we seem to find more reasons for concern.
Today, in NEJM’s Journal Watch, Richard T. Ellison III, MD (Professor of Medicine, Molecular Genetics and Microbiology in the Division of Infectious Diseases and Immunology at the University of Massachusetts Medical School) reviews four of these recent studies in a piece called:
Characteristics of the 2013 Influenza A (H7N9) Virus
Richard T. Ellison III, MD reviewing Zhou J et al. Nature 2013 Jul 3. Belser JA et al. Nature 2013 Jul 10. Watanabe T et al. Nature 2013 Jul 10. Zhu H et al. Science 2013 Jul 12.
A novel avian influenza A (H7N9) virus that causes human disease shows binding to human respiratory receptors, infectivity in multiple species, and respiratory-droplet transmissibility.
The four studies cited by Dr. Ellison will be familiar to regular readers of this blog, as we’ve discussed them all at some point over the past two months.
They are:
Zhou J et al. Biological features of novel avian influenza A (H7N9) virus. Nature 2013 Jul 3; [e-pub ahead of print] (see Nature: Biological Features Of H7N9).
Belser JA et al. Pathogenesis and transmission of avian influenza A (H7N9) virus in ferrets and mice. Nature 2013 Jul 10 (see Nature: H7N9 Pathogenesis and Transmissibility In Ferrets & Mice)
Watanabe T et al. Characterization of H7N9 influenza A viruses isolated from humans. Nature 2013 Jul 10 (see CIDRAP: Yesterday’s H7N9 Studies In Nature).
Zhu H et al. Infectivity, transmission, and pathology of human-isolated H7N9 influenza virus in ferrets and pigs. Science 2013 Jul 12 (See Branswell: Studies Show Transmissibility Of H7N9 In Ferrets).
Dr. Ellison nicely summarizes the major findings of all four studies, and then issues his own comment. His calls to control its spread in poultry and to develop a human vaccine are certainly well taken – but may prove difficult to achieve.
This H7N9 virus is currently non-pathogenic in poultry, which allows it to spread easily, and unnoticed, in farmer’s flocks.
In June, the FAO described some of the challenges facing China’s poultry industry in containing this virus (see FAO calls for continued vigilance in face of H7N9 avian influenza).
And while work is being done on the development of human H7N9 vaccine candidates (see Lisa Schnirring’s CIDRAP article Federal officials weigh H7N9 vaccine options), the road to actually having a vaccine that can be deployed (in any serious quantity) is likely a long and difficult one.
As Lisa points out in the above article, our limited experience with H7 and H5 vaccines suggests that they are more difficult to produce than vaccines for seasonal (or even the H1N1 pandemic) strains.
H5N1 vaccines required as much as 12 times as much antigen as seasonal flu vaccines, and still only produced modest immune responses.
In early May we saw an analysis of some of these problems published in JAMA, penned by CIDRAP’s Michael T. Osterholm, PhD, MPH; Katie S. Ballering, PhD; and Nicholas S. Kelley, PhD.
Major Challenges in Providing an Effective and Timely Pandemic Vaccine for Influenza A(H7N9)
Michael T. Osterholm, PhD, MPH; Katie S. Ballering, PhD; Nicholas S. Kelley, PhD
JAMA. 2013;():1-2. doi:10.1001/jama.2013.6589.
Published online May 9, 2013
Of course, we could get lucky.
In 1976 we were similarly watching a novel virus – swine H1N1 – that had appeared briefly the previous winter, and experts fully expected it to return in the fall (see Deja Flu, All Over Again).
But in that case, the virus was only detected in one location (Fort Dix, NJ), and was apparently contained on the army barracks.
H7N9 is far more widespread (detected across 10 Chinese provinces), and therefore less likely to go gently back into the wild.
All of which will make H7N9 surveillance a major concern for public health officials this fall.
