First recorded recent influenza pandemic
The “Spanish Flu” pandemic, caused by the H1N1 influenza virus, kills more than 40 million people. The origin of H1N1 remains a mystery, but may have involved incubation in an intermediate host, such as the pig, or another as yet unidentified animal host.
Asian flu pandemic kills 100,000 people, due to the H2N2 influenza virus.
Hong Kong flu pandemic kills 700,000 people, due to the H3N2 virus. Both H2N2 (1957 pandemic) and H3N2 are likely to have arisen by exchange of genes between avian and human flu viruses, possibly following dual infection in humans.
Bird flu virus H5N1 is isolated for the first time from a human patient in Hong Kong. The virus infects 18 patients after close contact with poultry, with six deaths. Fortunately the virus does not spread from person to person. Within three days, Hong Kong´s entire chicken population is slaughtered to prevent further outbreak.
Trial results announced for two new influenza drugs that target the virus’s neuraminidase enzyme, Relenza and Tamiflu, at the Interscience Conference on Antimicrobial Agents and Chemotherapy.
Two new flu drugs, Relenza and Tamiflu, are licensed in US and Europe.
The World Health Organization (WHO) outlines its new global laboratory proposal, aimed at improving the range, speed and quality of influenza virus surveillance (Science 293, 1729; 2001).
Alarm bells are again raised when the avian virus H5N1 infects two people in Hong Kong, one fatal.
Outbreaks of chicken flu occur in The Netherlands due to the H7N7 avian flu virus. By April the virus has spread to nearly 800 poultry farms and resulted in the culling of almost 11 million chickens. The virus infects 83 people causing conjunctivitis and flu-like symptoms, and kills one man. The drug Tamiflu helps protect people against further spread of the virus.
South Korea has its first outbreak of avian flu in chickens, caused by H5N1.
Japan has the first outbreak of avian influenza (H5N1) since 1925.
WHO confirms H5N1 infection in 11 people, eight fatal, in Thailand and Vietnam, but no cases of person to person transmission. The virus has wreaked havoc among poultry in Thailand, Vietnam, Japan and South Korea, and has also appeared in a duck farm in China.
WHO is developing vaccine candidates using H5N1 viruses isolated in 2003 and 2004, at laboratories in the U.S. and U.K.
United Nations Food and Agriculture Organization advises governments in affected areas that mass culling of birds is failing to halt the disease and that vaccination of targeted poultry flocks is required as well.
Avian H5N1 flu virus becomes more widespread among bird flocks in Asia, and has caused 34 human cases, with 23 deaths.
Avian influenza virus H7N3 confirmed in two poultry workers in British Columbia who developed flu-like symptoms.
Tests on chickens and mice show that avian flu H5N1 virus isolated from ducks in 2004 is more virulent and harmful to mammals than in recent years.
Several countries, including Thailand, Vietnam, China and Indonesia, report new infections in poultry with H5N1.
H5N1 is reported to have killed an additional three people in Vietnam.
Chinese scientists report H5N1 avian flu infection in pigs, raising concerns that the virus could exchange genes with human flu strains in this ´mixing vessel´.
H5N1 virus has spread throughout most of SE Asia, resulting in the culling of over 100 million chickens. In Vietnam and Thailand, the virus has infected at least 37 people, with 26 deaths.
UK authorities suspend manufacturing of this year’s routine influenza vaccine at the Liverpool factory of Chiron, owing to sterility concerns. The move leads to vaccine shortage particularly in the U.S. where Chiron supplies 50 per cent of the market, and highlights the need for alternative manufacturing sources.
WHO warns that the H5N1 bird flu virus might spark a flu pandemic that could kill millions of people, and is concerned that "much of the world is unprepared for a pandemic" and needs to enhance preparedness to reduce its potential impact.
WHO officials meet with vaccine makers, public-health experts and government representatives in a bid to speed up the production of flu vaccines to avert a global pandemic.
WHO reports the first human case of H5N1 in Vietnam since early September.
Sequencing of the chicken-genome (published in Nature 9 December 2004) may help provide insight into which genes prevent the spread of bird flu from person to person.
Since the beginning of 2004, bird flu has caused the deaths of 32 people in Vietnam and Thailand, and millions of chickens across Asia.
Chinese authorities announce they have developed a new rapid test for bird flu that produces results in hours rather than days.
13 additional cases of bird flu have occurred in Vietnam since December 2004, 12 fatal.
First report of a bird flu case from Cambodia.
A report of probable person to person transmission of bird flu in Vietnam is published (New Engl. J. Med, 352 333–340)
WHO has made prototype H5N1 vaccine strains available to a number of institutions and companies and several vaccines have been developed for clinical testing.
15 additional cases of H5N1 infection in Vietnam, and one additional case in Cambodia, are reported.
Bird flu has spread to 10 countries, including Democratic People´s Republic of Korea, and killed around 50 million chickens.
Vietnam has reported a total of 60 laboratory confirmed human cases of H5N1 avian influenza since the outbreaks began, with 35 deaths; Thailand has confirmed a total of 17 infections of which 12 have been fatal, while Cambodia has confirmed two fatal cases.