A chronology of the swine flu pandemic and the effort to develop, test and approve a vaccine for H1N1, which received federal government approval Wednesday:
March 18 -- Mexican government begins to track an increase in cases of severe respiratory illness in Mexico.
April 17 -- The CDC informs the World Health Organization it has found a case where an H1N1 swine flu virus infected a person in California. In the days that follow, scientists at CDC and several other labs start developing vaccine seed strains, the starting material for commercial vaccine production.
April 20 -- The Public Health Agency of Canada warns quarantine services to be on the lookout for sick travellers returning from Mexico.
April 26 -- Canadian officials confirm Canada's first cases.
April 27 -- The WHO raises the pandemic alert level to Phase 4 for the first time since the scale was created. Five countries have cases.
April 29 -- The WHO raises the pandemic alert level to Phase 5, one away from a pandemic. It says the virus is spreading from person to person in both Mexico and the United States. Officials announce first confirmed death in the U.S., a 23-month-old Mexican child who died in Houston.
May 8 -- Health officials confirm swine flu contributed to the death of a woman in northern Alberta who had pre-existing medical conditions.
May 19 -- A group of experts that counsels the World Health Organization on vaccine issues advises the WHO not to ask flu vaccine manufacturers to start full-scale production of swine flu vaccine just yet. To do so would have meant abandoning production of seasonal flu vaccine for the Northern Hemisphere.
May 27 -- Producers start to take possession of the vaccine seed strain and start working to grow up a seed stock of viruses, the first step in commercial production.
June 11 -- World Health Organization declares global H1N1 swine flu pandemic.
June 12 -- Swiss pharmaceutical firm Novartis AG says it has produced the first batch of H1N1 flu vaccine. Morocco reports first swine flu case and links it to a woman who arrived in the country from Montreal.
June 14 -- Swine flu death in Scotland marks first fatality outside of the Americas.
June 25 -- Canada's chief public health officer David Butler-Jones says vaccination program will likely roll out in the fall.
July 2 -- Britain revamps flu strategy in anticipation of seeing 100,000 cases a day by the end of August. Health Minister Andy Burnham says antiviral drug Tamiflu will now only be given to people confirmed to have the virus instead of those suspected to have it and those they have been in contact with. The change in strategy was meant to preserve resources and prevent people from developing resistance to the drug.
July 3 -- Health officials in Hong Kong report a case of tamiflu-resistant H1N1 in a woman who had not taken the drug, sparking fears that the virus is mutating and developing resistance to one of the few effective treatments.
July 6 -- Public Health Agency of Canada announces plans to spend $3.7 million on new ventilators to help treat H1N1. The 370 new ventilators would bring the national stockpile to 500.
July 7 -- The WHO's advisory group meets again and recommends production of H1N1 vaccine. But it also says manufacturers should finish off seasonal production first. That and the earlier decision mean the Northern Hemisphere has seasonal flu vaccine for this winter, but they also delayed the start of pandemic vaccine production.
July 12 -- The Canadian Press reveals vaccine manufacturers are getting an alarmingly low yield when they grow the new virus, getting between one-third and one-half what they get when they make seasonal flu vaccine. Work since has improved the yield but it is still lower than normal, a problem that is contributing to delivery delays.
July 23 -- Federal government approves use of Tamiflu for children under the age of one.
August 6 -- Federal government orders 50.4 million doses of H1N1 vaccine from GlaxoSmithKline and agrees to pick up 60 per cent of the more than $400-million tab.
Sept 4 -- Chief public health officer says Canada will buy 1.2 million doses of unadjuvanted swine flu vaccines -- or vaccines without compounds to boost the immune system-- which will be administered to pregnant women.
Sept. 11 -- World Health Organization reports 3,200 people have died of swine flu worldwide, with 74 of those deaths in Canada.
Sept. 22-- Quebec delays its seasonal flu shot program as experts reassess swine flu vaccination strategy.
Sept. 23 -- Unpublished Canadian data suggest people who received a seasonal flu shot last year are about twice as likely to catch swine flu as those that did not.
Sept. 24 -- Ontario reschedules seasonal flu vaccine program. Only those age 65 or older can receive seasonal flu shots in October. Pandemic vaccines will be administered in November, with season shots resuming after that.
Sept. 28 -- British Columbia and Prince Edward Island announce delays to seasonal flu shot program, joining Nova Scotia, Quebec and Saskatchewan.
Sept. 30 -- Public Health Agency of Canada says early analysis does not back up study claiming those that received seasonal flu shots are more likely to contract swine flu.
Oct. 4 -- World Health Organization says countries do not need to change their season flu shot policies based on unpublished Canadian data establishing a link between the shots and the risk of contracting swine flu.
Oct. 8 -- Harris-Decima poll suggests only a third of Canadians plan to get vaccinated against swine flu.
Oct. 13 -- Head of PHAC David Butler Jones says provinces have prepared to roll out their pandemic vaccinations ahead of schedule if necessary.
Oct. 18 -- Public health official says provinces and territories have already received shipments of vaccine, which will be rolled out pending government approval.
Oct. 21 -- Health Minister Leona Aglukkaq approves swine flu vaccine; provinces will begin offering vaccinations as early as next week.
