The thin line represents average mortality of recent cases. The thicker line represents mortality averaged over all cases.
According to WHO: "Assessment of mortality rates and the time intervals between symptom onset and hospitalization and between symptom onset and death suggests that the illness pattern has not changed substantially during the three years."[1]
H5N1
Influenza A virus
subtype H5N1
Genetic structure
Infection
Human mortality
Global spread
in 2004
in 2005
in 2006
in 2007
2020–2024
Social impact
Pandemic
Vaccine
v
t
e
This article needs to be updated. Please help update this article to reflect recent events or newly available information.(March 2020)
Human mortality from H5N1 or the human fatality ratio from H5N1 or the case-fatality rate of H5N1 is the ratio of the number of confirmed human deaths resulting from confirmed cases of transmission and infection of H5N1 to the number of those confirmed cases. For example, if there are 100 confirmed cases of humans infected with H5N1 and 50 die, then there is a 50% human fatality ratio (or mortality rate). H5N1 flu is a concern due to the global spread of H5N1 that constitutes a pandemic threat. The majority of H5N1 flu cases have been reported in southeast and east Asia. The case-fatality rate is central to pandemic planning. Estimates of case-fatality (CF) rates for past influenza pandemics have ranged from to 2-3% for the 1918 pandemic to about 0.6% for the 1957 pandemic[1] to 0.2% for the 1968 pandemic. As of 2008, the official World Health Organization estimate for the case-fatality rate for the outbreak of H5N1 avian influenza was approximately 60%.[2] Public health officials in Ontario, Canada argue that the true case-fatality rate could be lower, pointing to studies suggesting it could be 14-33%, and warned that it was unlikely to be as low as the 0.1–0.4% rate that was built into many pandemic plans.[2]
H5N1 infections in humans are generally caused by bird to human transmission of the virus. Until May 2006, the WHO estimate of the number of human to human transmissions had been "two or three cases". On May 24, 2006, Dr. Julie L. Gerberding, director of the United States Centers for Disease Control and Prevention in Atlanta, estimated that there had been "at least three." On May 30, Maria Cheng, a WHO spokeswoman, said there were "probably about half a dozen," but that no one "has got a solid number."[3] The cases of suspected human to human transmission that continue to be found have been isolated and contained,[4] and include transmission among members of a family in Sumatra, Indonesia in June 2006[5] as well as earlier and later instances arising in other countries. However, no pandemic strain of H5N1 has yet been found. The key point is that, at present, "the virus is not spreading efficiently or sustainably among humans."[6]
H5N1 vaccines for chickens exist and are sometimes used, although there are many difficulties that make it especially difficult to decide whether vaccination will do more harm than good. In the U.S. H5N1 pre-pandemic vaccines exist in quantities sufficient to inoculate a few million people[7] and might be useful for priming to "boost the immune response to a different H5N1 vaccine tailor-made years later to thwart an emerging pandemic".[8] Japan has inoculated 6,000 health care workers with a pre-pandemic vaccine, and is planning how to proceed with widespread vaccinations, particularly workers who would provide utilities during an outbreak.[9][10][11] Switzerland is also considering preemptive vaccination to protect the general public.[12] H5N1 pandemic vaccines and the technologies to rapidly create them are in the H5N1 clinical trials stage but cannot be verified as useful until after a pandemic strain emerges. Efforts to identify the changes that might result in a human-communicable strain have resulted in laboratory-generated H5N1 with substantially greater affinity for human cellular receptors after a change of just two of the H5 surface proteins.[13] Significantly, mouse antibodies were 10 times less potent against the mutants than against the pre-mutated viruses.[13]
^Lovelace Jr., Berkeley (26 March 2020). "The coronavirus may be deadlier than the 1918 flu: Here's how it stacks up to other pandemics". CNBC. f NBCUniversal. Retrieved 25 April 2020.
^ abLi FC, Choi BC, Sly T, Pak AW (June 2008). "Finding the real case-fatality rate of H5N1 avian influenza". J Epidemiol Community Health. 62 (6): 555–9. doi:10.1136/jech.2007.064030. PMID 18477756. S2CID 34200426.
^Donald G. McNeil Jr. (June 4, 2006). "Human Flu Transfers May Exceed Reports". New York Times.
^"Seven Indonesian Bird Flu Cases Linked to Patients". Bloomberg. May 23, 2006. Archived from the original on October 7, 2007.
^"WHO confirms human transmission< in Indonesian bird flu cluster".
^"Avian influenza – situation in Indonesia – update 17". WHO. June 6, 2006. Archived from the original on June 15, 2006.
^"HHS has enough H5N1 vaccine for 4 million people". CIDRAP. July 5, 2006.
^"Study supports concept of 2-stage H5N1 vaccination". CIDRAP. October 13, 2006.
^Pre-pandemic bird flu shots eyed / Health ministry to urge study of potential early vaccination recipients
|
(Daily Yomiuri Online + AP -- Apr. 25, 2009)
http://www.yomiuri.co.jp/dy/national/20090425TDY03103.htm
^
"Japan to vaccinate medical workers for bird flu". Reuters. 2008-04-15. Retrieved 2023-05-11.
^Measures against flu needed / Govt urged to set up framework to fight new influenza outbreak
Apr. 24, 2008
http://www.yomiuri.co.jp/dy/features/science/20080424TDY04302.htm
^Vaccinations for new flu strains eyed for public (Apr. 17, 2008) http://www.yomiuri.co.jp/dy/national/20080417TDY02301.htm
^ abhttp://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/aug1007mutant.html Researchers create H5N1 mutations to pave way for new vaccines and treatments
Aug 10, 2007 (CIDRAP News)
"Focusing on genetic changes to one portion of the H5 protein, called the receptor binding domain, [the researchers] found that as few as two mutations could enhance the ability of H5N1 to recognize human cells, according to the press release."
Yang ZY, Wei CJ, Kong WP, et al. (August 2007). "Immunization by avian H5 influenza hemagglutinin mutants with altered receptor binding specificity". Science. 317 (5839): 825–8. Bibcode:2007Sci...317..825Y. doi:10.1126/science.1135165. PMC 2367145. PMID 17690300.
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