This chronology of the pandemic will be updated regularly as news breaks and past events come to light. And follow ScienceInsider's full coverage on the swine flu outbreak.
This chronology of the pandemic will be updated regularly as news breaks and past events come to light. And follow ScienceInsider's full coverage on the swine flu outbreak.
With the novel H1N1 virus "widespread" in 47 states, U.S. CDC Director Thomas Frieden concedes that the vaccine will "arrive too late for many" Americans. Frieden reveals that, once again, manufacturers have missed their targets and provided less vaccine than predicted. But the vaccine may still benefit people if a third wave of the virus shows up in the winter, he says. HHS official Nicole Lurie clarifies the specific delays that have occurred with four of five suppliers, describing something of a perfect storm of unforeseen problems. In all, 16.1 million doses are available in the country, and projections call for an increase of about 8 million to 10 million doses per week.
Vaccine manufacturers notify the U.S. government that they cannot deliver as much H1N1 vaccine as projected this month. In all, the country has 11.4 million doses of vaccine available, far short of the 40-million-plus doses it hoped to have by mid-October. The World Health Organization reports that H3N2, a seasonal strain of the virus, now accounts for "nearly half" of the influenza isolates detected in China. The U.S. CDC reports that 99% of isolates are still the novel H1N1.
Opposition to the swine flu vaccine mounts worldwide, with doubts about safety and efficacy being raised by both extremes of the political spectrum in the United States, as well as several celebrities.
Amid growing complacency in the United States about the H1N1 pandemic, U.S. health officials emphasize that the virus is killing more children than seasonal strains typically do and downplay reports that some regions of the country may be spared because they were hard hit in the spring wave. The officials also emphasize studies that show no impact of the seasonal vaccine on the pandemic virus, discounting reports to the contrary.
CDC has only 2.4 million doses of vaccine but expects large lots to begin arriving in the next few weeks. Dilemma shifts from who should receive limited supplies to addressing widespread reluctance to receive vaccine.
First person in United States receives swine flu vaccine.23 September
WHO recommends that next winter's seasonal vaccine for the Southern Hemisphere lose the H1N1 component, as it appears to have disappeared after the pandemic H1N1 spread widely. The seasonal vaccine currently contains H1N1, H3N2, and a type B, Brisbane strain. WHO's Strategic Advisory Group of Experts will decide when it meets in late October whether the new seasonal vaccine should include the novel H1N1 virus or if it should be given separately along with an H3N2/Brisbane vaccine.
NIH reports early results from clinical trials of swine flu vaccine in children that show kids under 10 will likely need two doses, while the 10-17 age group can get by with one.
CDC says it expects to have the first batch of swine flu vaccine delivered the first week in October. The 3.4 million doses will be live, attenuated vaccine, which cannot be used by everyone.
U.S. President Barack Obama announces that the United States and seven other wealthy countries will share 10% of their swine flu vaccine with developing countries.
FDA approves four swine flu vaccines.
China launches a mass vaccination campaign against swine flu with vaccines made and approved in-country.
Increasing numbers of flu experts worry that the vaccine will not arrive in time to blunt the fall wave of the pandemic in the United States. On the good news front, clinical trials of novel H1N1 vaccine suggest that a single dose will protect adults.
HHS issues a report about how the novel H1N1 virus behaved during the winter in seven countries in the Southern Hemisphere. The virus had very few genetic changes, and cases typically began to decrease in July, indicating that it took about 6 to 7 weeks from the first report of an epidemic to its peak.
The U.S. President's Council of Advisors on Science and Technology issues a report about the swine flu pandemic that predicts as many as 90,000 Americans might die from the virus. If vaccine begins to arrive in mid-October and the model is correct about viral spread in the country, PCAST warns "a vaccination campaign would not begin to protect vaccinees until well after the epidemic had peaked."
Chile reports finding the novel H1N1 virus in turkeys. CDC says it does not expect vaccine to start arriving until mid-October, tempering hopes of getting a jump on the virus when cases begin to climb in concert with kids returning to schools.
The Advisory Committee on Immunization Practices (ACIP) that advises CDC meets in Atlanta and recommends that U.S. government launch a vaccine program against swine flu. ACIP further spells out which groups should receive vaccine first if supplies, as expected, are limited.
Mexico reports that it searched through old samples and found the earliest confirmed case yet of a novel H1N1 infection, which dates back to 24 February. Criticism of U.S. government mounts for its refusal to use adjuvant to stretch vaccine supplies to make it more available for other countries.
CDC stops reporting specific number of confirmed cases in the country, which total 43,771. Estimates suggest there are actually "well over a million." Vaccine manufacturers report they are having difficulty growing the influenza virus, meaning they have lower yields of the critical antigens needed to make the product.
As clinical trials of swine flu vaccines begin in Australia and China with products made in those countries, NIH announces elaborate plans to conduct various trials in the United States.
Amidst growing concern about vaccine production problems and the possibility that countries where the product is produced may hoard it, CDC says the United States--which purchases most of its vaccine from foreign manufacturers--is confident that it will have the supply it needs. Although U.S. officials suspect the vaccine will not need adjuvant, the possibility of a shortage leads to increasing discussions about using adjuvants to stretch the amount of available vaccine, tilting the risk/benefit equation to favor what's best for the public rather than the individual.
Vaccine manufacturers are having difficulty producing normal amounts of vaccine against the pandemic H1N1 virus using eggs, and WHO announces that it is producing new seed stocks that they hope will produce higher yields.
The White House convenes a "flu summit" at NIH to prepare states for the fall wave.
WHO's Strategic Advisory Group of Experts on immunization meets and concludes that health care workers should be the first to receive vaccines against the novel H1N1 virus.
Hong Kong reports that a 16-year-old Californian girl who landed at Hong Kong International Airport on 11 June was infected with the Tamiflu-resistant virus. She never took the drug herself, raising concerns that resistance might be spreading.
The U.S. government announces that it will donate 420,000 courses of Tamiflu to Latin America.
WHO and two other international agencies rename the virus "Pandemic (H1N1) 2009" but do not make an official announcement and the naming confusion continues.
A woman in Denmark develops the first detected strain of virus that has a resistance mutation for the drug Tamiflu. Officials say it does not represent a public health threat because she developed the resistance while taking the drug and did not appear to infect others. The main worry scientists have is that the novel H1N1 strain will pick up the resistance from the seasonal H1N1 virus, which is highly transmissible between people.
CDC estimates that up to one million people in the United States are infected.
Argentina reports that the novel H1N1 virus has infected a pig farm, only the second time that the virus has been found in a swine herd. As with the first case, officials strongly suspect the transmission occurred from an infected human to the pigs.
CDC says the virus will likely stick around for the summer in the United States, estimating that hundreds of thousands of people in the country have now been infected. South Africa confirms a case, the first one south of the Sahara Desert.
Vaccine maker Sanofi-Aventis announces plans to donate 100 million doses of its A(H1N1) pandemic vaccine, doubling the number offered by GlaxoSmithKline the week before. Novartis, the third major producer of flu vaccine, says it will not donate vaccine but will consider a price break for developing countries. The U.S. House of Representatives approves $7.65 billion in new money to respond to the pandemic.
A 38-year-old woman in Scotland with underlying health conditions dies of swine flu, the first death outside of the Americas attributed to the novel H1N1 virus.
Vaccine maker Novartis announces that it has made the first batch of vaccine against the novel H1N1 virus and plans to start pre-clinical tests. The company claims that its cell-based production technique "shows significant time saving" over traditional egg-based methods and says 30 governments have requested their product.
WHO finally declares a phase 6 alert. At a press conference, WHO Director General Margaret Chan explains that she consulted member countries and her emergency committee and that there was "a unanimous decision, that we have indisputable evidence that we are at the beginning days of a global pandemic caused by a new H1N1 virus." Confirmed cases reported to WHO from 74 countries total 28,774 and 144 deaths.
With Australia reporting more than 1000 confirmed cases, WHO's flu chief Keiji Fukuda says the agency is now "really very close" to calling the epidemic a pandemic WHO is still working to inform countries exactly what phase 6 means and to avoid a "blossoming of anxiety" once a pandemic is declared. Fukuda also weighed in on what the virus--or the pandemic--should be called, admitting that the current name, influenza A (H1N1), is creating confusion.
Egypt becomes the first country in Africa to report a confirmed case of swine flu to WHO. Pan-African News Agency reports that six sub-Saharan countries have suspected cases. In all, says WHO, 73 countries to date have reported 25,288 confirmed cases and 139 deaths.
Trust for America's Health, a D.C.-based advocacy group, issues "Pandemic Flu Preparedness: Lessons from the Frontlines." The detailed critique praises U.S. federal, state, and local governments for having invested in pandemic planning, including the stockpiling of drugs and training public health officials to respond appropriately. But the report says public health departments are underfunded and "stretched too thin," leading to delays in identifying and containing infections.
The 23-page report further warns that the country's "current vaccine development and production capacity is severely lacking," adding that "the country has not developed or adequately tested a system that will ensure that all Americans would be able to be inoculated in a short period of time." WHO's pandemic alert system, it says, has caused much confusion; the report also criticized some countries for instituting travel restrictions and bans on pork products.
Australia reports 501 confirmed cases, up from 17 a week before, making the island nation the hardest-hit country outside of North America. With increasing fears about the spread of H1N1 in the Southern Hemisphere, Asia, and Europe, WHO announces that it's moving closer to declaring a phase 6 alert, but says it likely will include a severity index tailored for each locale based on both viral characteristics and ability to respond. U.S. President Barack Obama sends a letter to Nancy Pelosi, speaker of the House of Representatives, asking Congress to set aside nearly $10 billion new dollars for swine flu. This would add to the $2 billion a House bill already in the works. Obama made the request out of "an abundance of caution" and the funds would only be tapped if a full-scale pandemic hit the United States.
Swine flu begins to spike in the Southern Hemisphere, with 74 confirmed cases in Chile alone. The CDC suggests that the disease may have peaked in the United States, as reports of influenza-like illness declined in seven of nine regions. But this does not directly measure the actual prevalence of the novel H1N1 virus, and some epidemiologists caution against undue optimism. CDC also warns that even if the drop is real in the United States--which accounts for just over half of the world's 12,954 confirmed cases--the virus has not left and may well come roaring back with the cooler weather in the fall.
Following complaints from member countries at the World Health Assembly meeting held in Geneva this week, WHO announces that it needs to rethink its phasing system and the definition of the word "pandemic." Despite mounting cases outside of the Americas, the member countries surged WHO not to declare a phase 6 alert, contending that the swine flu does not cause severe enough disease to warrant the label of a full-scale pandemic. Meanwhile, the U.S. Department of Health and Human Services announces that it will dish out $1 billion to several pharmaceutical companies to make a vaccine against the novel H1N1 virus. But the money will only purchase vaccine ingredients, not a final product, and it's only enough material to vaccinate 20 million people. ScienceExpress publishes the first detailed study of the new virus's genetic makeup, explaining the twisted histories of its closest relatives.
MMWR dispatch offers the first concrete evidence that the elderly population may have some immunity to the new virus, which could explain why they largely have been spared from severe disease in this outbreak. According to the study, antibodies from this group worked against the novel H1N1 virus in test tube experiments. The cross-reactive antibody response may reflect their exposure to the H1N1 virus that circulated until 1957, MMWR suggests.
Confirmed world cases top 10,000. CDC clarifies that no delays expected for vaccine production as many processes are done in parallel, which wasn't clear from the WHO report the day before. Still, concerns remain about whether a vaccine can actually be manufactured and approved in time for traditional flu season in the Northern Hemisphere.
WHO releases a report from an ad hoc advisory group looking at making vaccines against the new virus, which suggests the "seed stock" needed to scale-up production of a H1N1 vaccine may not be ready until mid-July. This is two months later than an estimate made by WHO's Marie-Paul Kieny on 1 May. Given that it takes up to six months to manufacture vaccine, this raises questions about whether it will be ready in time for winter in the Northern Hemisphere. Confirmed cases in Japan climb to 191, mostly among school children, and higher than any country outside of the Americas.
At the opening of the World Health Assembly in Geneva, several countries urged WHO Director-General Margaret Chan to revise the pandemic alert system, as it reflects geographic spread but not the severity of disease. Chan says the alert level will remain at phase 5, despite Japan reporting 129 cases--up from four a few days earlier. She says, "The virus has given us a grace period" but cautions against complacency. "No one can say whether this is just the calm before the storm." Cases in Japan continue to climb.
Japan reports sharp spike in cases. There is increasing pressure on WHO to raise the alert level from phase 5 to 6
With apathy setting in, CDC's Daniel Jernigan, deputy director of the influenza division, stresses that "the H1N1 virus is not going away." Jernigan estimates that "upwards of maybe 100,000" people in the United States have influenza-like illness--more than 20 times the number of confirmed and probable novel H1N1 cases in the country. But Jernigan says some of the spike in flu cases likely comes from seasonal viruses, not the new strain, as well as the "profound amount of testing that has gone on in the last few weeks." CDC also changes its recommendations for people who want to travel to Mexico, downgrading the "warning" that advised people to put off "nonessential" trips to a "precaution." In Europe, which has yet to see sustained transmission in communities, four countries cut deals with GlaxoSmithKline to purchase more than 100 million doses of a vaccine that targets the new H1N1 virus.
A Texan whose pregnant wife died of swine flu takes legal action against the U.S. co-owner of a Mexican pig farm, Granjas Carroll, which he alleges may have kick-started the outbreak. WHO announces that it no longer will hold daily press briefings.
With the outbreak still teetering on the brink of phase 6, a full-scale pandemic, WHO's Sylvie Briand, a project leader in the Global Influenza Programme, acknowledges the limits of the phasing system, which gauges transmission, not severity. But Briand says a "severity index" for flu "is not very helpful" because it depends on several factors that can differ even within one country, including virulence, vulnerability, and community "resilience." CDC, for the first time since 23 April, will no longer hold daily press briefings.
WHO and CDC officials suggest that European and Asian countries may have made headway against the virus with aggressive screening of travelers and prompt treatment of infected people and their contacts with antivirals. CDC's MMWR dispatch advises use of antiviral drugs for any pregnant woman with confirmed disease. Thirty countries report more than 5200 confirmed cases, nearly 90% of which were in Mexico and the United States, but WHO and CDC advise that case counts are underestimates. Story breaks about scientist who suggests that the virus might be an accidental laboratory creation, which immediately is met with deep skepticism.
Mainland China reports its first case. Science publishes a paper that estimates 23,000 people in Mexico were infected by 30 April, and that the virus looks similar in severity to one that caused 1957 pandemic.
Confirmed cases in the U.S. (1639) outnumber those in Mexico (1364) for the first time, but this might reflect more aggressive surveillance and testing capabilities than actual infections.
Mexico reports nearly 12,000 suspected cases, more than 1000 confirmed. WHO says community transmission does not appear to be happening outside the Americas. A media backlash begins, accusing scientists and officials of hyping the outbreak. Canadians clarify details about the pig farm outbreak, noting that others on the farm developed influenza-like illness but have tested negative for the virus.
Canada reports that the worker on the Alberta pig farm tested negative for the virus, although the sample may have been collected too late to detect it. Tests of his blood for antibodies begin.
First death of a U.S. resident: a 33-year-old schoolteacher who had recently given birth. CDC announces that schools should no longer close if they have a case. Mexico's Córdova says cases are decreasing in severity and number, and that businesses in Mexico City may reopen. Mexico reports the detection of a Mexico City case with symptoms on 11 March, earliest date yet reported.
Official case count tops 1000 for first time. Virus found in 20 countries.
WHO reports 18 countries with 898 confirmed cases. Phase 6, full-scale pandemic, remains imminent but not declared.
Canada reports the first isolation of the virus from pigs. A farm worker who traveled to Mexicali, Mexico, returned to Canada on 12 April and apparently infected a herd in Alberta. Mexican Health Minister José Ángel Córdova says he believes the outbreak in his country is stabilizing. Mexico still has a backlog of untested samples but has confirmed 506 cases and 19 deaths. U.S. cases climb to 226 and 30 hospitalizations.
Thirteen countries report cases, taking the total to 367. Between 1billion and 2 billion doses of a pandemic vaccine may be available within a year, says WHO's Marie-Paule Kieny. Ensuring access for the world's poorest is a WHO priority, she says.
The backlog of untested cases is in the thousands, as few labs other than CDC and PHAC can confirm cases. MMWR publishes detailed reports about outbreaks in Mexico and a New York City school. In London, the European Medicines Agency meets with E.U. member countries, vaccine producers, WHO, and the European Centre for Disease Prevention and Control to discuss the criteria a pandemic vaccine will have to meet.
WHO raises the threat level from phase 4 to 5, indicating sustained community transmission in two countries (Mexico and the United States) in the same region. Ten countries report confirmed cases, including South Korea, the first in Asia. The first related death is reported in the United States: a toddler from Mexico visiting relatives. WHO's Chan holds a teleconference with vaccine manufacturers around the globe to discuss the production of a pandemic vaccine.
Seven countries report cases to WHO. CDC reports five new hospitalized cases in the United States, and acting CDC Director Richard Besser says he expects to see deaths. The Mexican government bans dining in Mexico City restaurants. Cuba suspends flights to and from Mexico, becoming the first of several countries to do so.
Canada and Spain report confirmed cases to WHO. After an Emergency Committee meeting, WHO raises the pandemic threat level from phase 3 to phase 4, indicating sustained human-to-human transmission in a community. Mexico suspends schools nationwide.
CDC confirms cases in five states, none severe. The mystery deepens about why Mexico appears to have many related hospitalizations and deaths. Other countries, including New Zealand and France, report suspect cases. Churches in Mexico City do not hold mass
WHO convenes an Emergency Committee to evaluate evidence. Chan declares the outbreak a Public Health Emergency of International Concern 24 April
CDC publishes MMWR dispatch about six new U.S. cases with increasing evidence of human-to-human transmission and publicly links same strain of H1N1 to the Mexican outbreak. WHO receives reports from Mexico of 884 suspected cases, most in Mexico City, and 62 deaths. Most cases are in otherwise healthy young adults. The Mexican government closes schools in Mexico City.
Samples from Mexico arrive at CDC. PHAC and CDC confirm Mexico cases are the same A(H1N1) of swine origin.
There is a teleconference between PHAC, CDC, and Mexican officials. Genetic analysis shows that the virus is a mix of avian and swine viruses from North America, a swine flu strain usually seen in Asia, and a human influenza strain. Margaret Chan, WHO's director general, learns details upon arrival in Washington, D.C., for World Malaria Day and quickly returns to Geneva. In a press conference, CDC says it's producing a "seed strain" for the production of a pandemic vaccine.
Samples from Mexico arrive at PHAC. 21 April
CDC publishes first dispatch in the Morbidity and Mortality Weekly Report (MMWR) about two cases in California. Mexico reports atypical influenza behavior associated with severe pneumonia in various cities. InDRE ships samples to PHAC's National Microbiology Laboratory in Winnipeg and CDC.
Teleconference with CDC, PAHO, and PHAC. Cooperation established between Mexico, the United States, and Canada.
The U.S. focal point publishes confirmed California cases of A(H1N1) in WHO's EIS. Mexico acknowledges receipt of information and responds that in March and April the country had an unusual increase in seasonal influenza with predominance of B strain; some cases presented with severe pneumonia in adults of reproductive age. Mexico notes that the case of a severe pneumonia in patient who died in Oaxaca could be related. PHAC and InDRE have teleconference and conclude it may be a novel agent, unrelated to influenza17 April
Mexican focal point asks local officials in Mexico to verify news reports of a cluster of cases of acute respiratory illness in Oaxaca hospital. Officials reply there is no such outbreak, but there is one patient with diabetes who has a severe case, presumably viral. InDRE Director Celia Alpuche sends an e-mail asking for help to Francis Plummer, head of the National Microbiology Laboratory in Winnipeg, part of the Public Health Agency of Canada (PHAC).
CDC notifies San Diego County Health & Human Services Agency of a local case of a novel swine influenza. PAHO receives a news story alert from Veratect about a supposed coronavirus outbreak in a hospital in Oaxaca state. 14 April
CDC tests the San Diego boy's sample and determines the virus is A(H1N1) of swine origin. The boy had no contact with pigs.
Wisconsin's State Laboratory of Hygiene tests specimen, confirms that it's untypable, and sends to CDC. NHRC also sends CDC a sample of isolated virus. PAHO asks Mexico's focal point if it can post a notice about the outbreak in WHO's surveillance network's Event Information System (EIS). Mexico's focal point doesn't respond.
Mexico's director general of epidemiology, Hugo López-Gatell Ramírez, confirms to PAHO the existence of acute respiratory infections but says there is no link to fecal contamination of pig farms. Studies continue. Mexico's focal point considers outbreak to be a "potential public health event of international importance" because it meets IHR criteria: severe public health impact and an unusual event.
As per the International Health Regulations (IHR), the World Health Organization (WHO) has a pandemic alert and response network, which relies on designated people or institutions in each member country to report unusual disease patterns. PAHO, a regional office of WHO, asks the Mexican IHR "focal point" to verify the outbreak reported in the news.
The Pan American Health Organization (PAHO) accesses Veratect database and notes news stories reporting an outbreak of acute respiratory infections in La Gloria, Veracruz. Wisconsin State Laboratory of Hygiene in Madison receives sample of San Diego boy from Marshfield Labs.
Instituto Nacional de Diagnóstico y Referencia Epidemiológicos (InDRE), the main influenza diagnostic lab in the country, located in Mexico City, learns of unusual severe respiratory diseases in young adults seen at the National Institute of Respiratory Diseases and begins investigating the cluster.
Veratect, a Kirkland, Washington-based company that scours news reports for emerging threats, reports in its subscription-only database that local Mexican health officials have declared an alert because of respiratory disease outbreak in La Gloria, Veracruz state, Mexico. Residents believe it is caused by pig breeding farms in the area. Local officials launch a spraying campaign that targets flies, an influenza vaccination campaign, and an epidemiological investigation back to 10 March. A Mexican news story reports 60% of inhabitants infected and three deaths.
NHRC researchers determine that the boy is likely infected with influenza A, but they cannot subtype the strain. As per protocol, the sample is sent to Marshfield Labs in Wisconsin. HealthMap, a global disease alert system run by academics, flags a news story from Mexico about a strange respiratory outbreak in the state of Veracruz that has claimed two lives.
A 10-year-old boy with fever, cold, and vomiting goes to the Naval Medical Center San Diego in California. As part of a clinical study, a nasopharyngeal swab is sent across town to the Naval Health Research Center (NHRC).
Mexican surveillance begins noting cases of influenza-like illness in the Distrito Federal, which includes Mexico City.
First documented symptoms (as of 5 May) in a Mexico City resident who later would be found to have confirmed infection with A(H1N1) swine flu.
Sources: Mirta Roses Periago and Daniel Epstein, PAHO; Celia Alpuche, InDRE; Mauricio Hernandez-Avilia, Mexican Ministry of Health; Francis Plummer, PHAC; CDC, WHO, and Mexican government press conferences; Veratect; Michele Ginsberg, San Diego County Health & Human Services Agency; U.S. Naval Health Research Center, HealthMap.