2009-2010 Swine Flu Pandemic

created Thu, Mar 12, 2020


This week, the World Health Organization labeled the COVID-19 virus a pandemic. The last influenza pandemic was the 2009-2010 Swine Flu, and I don't remember anything about it.

This afternoon while listening to a local talk radio show on AM 1370, a caller said that his 23-year-old daughter died from 09-Swine Flu. The caller said that it was a pandemic. Since I recalled nothing about that pandemic, and it occurred only 11 years ago, I searched for info.

Today, I read about the Swine Flu Pandemic on the CDC website and at Wikipedia. The first officially documented case in the world occurred in April 2009 in the United States or in March 2009 in Mexico. The CDC page and the Wikipedia page show different info.

That spring some elementary and high schools closed, but I don't know about universities. The CDC recommended universities suspend fall classes IF the outbreak was worse than in the spring.

In the spring of 2009, some communities implemented social-distancing plans. The 2009 Swine Flu was a bit different because it mainly impacted people under the age of 65. It was found that a significant percentage of people 65-and-over had anti-bodies to the virus.

In June 2009, the WHO declared a pandemic. A vaccine became available in November 2009 after the peak of the 09-Swine Flu.

In 2009-2010, I worked at the Black Swamp Bird Observatory, supporting the Ohio Young Birders Club, and we never cancelled any of our field trips, conferences, and other public events and gatherings.

From April 2009 to April 2010, the CDC estimated that in the U.S., over 12,000 people died from 09-Swine Flu from 60 million cases. In that one year period, the CDC estimated that between 151,000 and 575,000 people died worldwide from the 09-Swine Flu. But these CDC numbers seem to be disputed by the numbers presented in the corresponding Wikipedia page, listed below.

Globally, the 09-Swine Flu killed a much smaller percentage of people per cases, compared to other influenza pandemics. I think that the "recent" previous flu pandemics occurred in the late 70s and the late 60s. It's possible that advancements in medicine and care have occurred over the past 50 years that help limit the death rate.

Officially, the 2009 Swine Flu is called A(H1N1)pdm09. According to the CDC, that strain of flu is now:

"... a regular human flu virus and continues to circulate worldwide seasonally."

Our annual flu shot covers that strain of flu. I think that Covid-19 will also become a regular human virus that occurs seasonally. Hopefully, a vaccine will be created for Covid-19, and it might become a part of our annual flu shot.

Obviously, each flu strain is different, and it's invalid to compare 09-Swine Flu to Covid-19 on technical matters, but both were labeled pandemics, and I can't believe that I don't recall anything about the 2009 Swine Flu, which occurred only 11 years ago. My Stepdaughter graduated from a Toledo high school in the spring of 2009, and I don't remember any concerns.

For Covid-19, the incubation and contagious periods are much different, and the death rate appears to be much higher.

Regarding our current pandemic, why are people buying so much toilet paper this week? People seem to be buying everything at grocery stores. Huge lines have been reported this week in Toledo. Shelves emptied. People are buying cases of bottled water. Why? We have good tap water that tastes even better when run through a filtered pitcher. A run on bottled water????

The problem is, people are buying things that they don't need, and that's interfering with other people who now cannot buy the things that they do need. Some local impoverished people are unable to buy baby formula because of others buying too much. We are experiencing too much selfish behavior.

Is this week's panic-buying in Toledo and elsewhere a result of most Americans, spending too much time using social media on their phones?

This is a 2019 post, a 10-year update or look back on the 09-Swine Flu.


In the spring of 2009, a novel influenza A (H1N1) virus emerged. It was detected first in the United States and spread quickly across the United States and the world. This new H1N1 virus contained a unique combination of influenza genes not previously identified in animals or people. This virus was designated as influenza A (H1N1)pdm09 virus. Ten years later work continues to better understand influenza, prevent disease, and prepare for the next pandemic.

The (H1N1)pdm09 virus was very different from H1N1 viruses that were circulating at the time of the pandemic. Few young people had any existing immunity (as detected by antibody response) to the (H1N1)pdm09 virus, but nearly one-third of people over 60 years old had antibodies against this virus, likely from exposure to an older H1N1 virus earlier in their lives. Since the (H1N1)pdm09 virus was very different from circulating H1N1 viruses, vaccination with seasonal flu vaccines offered little cross-protection against (H1N1)pdm09 virus infection. While a monovalent (H1N1)pdm09 vaccine was produced, it was not available in large quantities until late November—after the peak of illness during the second wave had come and gone in the United States. From April 12, 2009 to April 10, 2010, CDC estimated there were 60.8 million cases (range: 43.3-89.3 million), 274,304 hospitalizations (range: 195,086-402,719), and 12,469 deaths (range: 8868-18,306) in the United States due to the (H1N1)pdm09 virus.

Additionally, CDC estimated that 151,700-575,400 people worldwide died from (H1N1)pdm09 virus infection during the first year the virus circulated.** Globally, 80 percent of (H1N1)pdm09 virus-related deaths were estimated to have occurred in people younger than 65 years of age. This differs greatly from typical seasonal influenza epidemics, during which about 70 percent to 90 percent of deaths are estimated to occur in people 65 years and older.

Estimates of pandemic influenza mortality ranged from 0.03 percent of the world’s population during the 1968 H3N2 pandemic to 1 percent to 3 percent of the world’s population during the 1918 H1N1 pandemic. It is estimated that 0.001 percent to 0.007 percent of the world’s population died of respiratory complications associated with (H1N1)pdm09 virus infection during the first 12 months the virus circulated.

The United States mounted a complex, multi-faceted and long-term response to the pandemic, summarized in The 2009 H1N1 Pandemic: Summary Highlights, April 2009-April 2010. On August 10, 2010, WHO declared an end to the global 2009 H1N1 influenza pandemic. However, (H1N1)pdm09 virus continues to circulate as a seasonal flu virus, and cause illness, hospitalization, and deaths worldwide every year.

"The 2009 H1N1 Pandemic: Summary Highlights, April 2009-April 2010" - Updated: June 16, 2010


Content on this page was developed during the 2009-2010 H1N1 pandemic and has not been updated.

The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.

The English language content on this website is being archived for historic and reference purposes only.

For current, updated information on seasonal flu, including information about H1N1, see the CDC Seasonal Flu website.

Infection with this new influenza A virus (then referred to as ‘swine origin influenza A virus’) was first detected in a 10-year-old patient in California on April 15, 2009, who was tested for influenza as part of a clinical study. Laboratory testing at CDC confirmed that this virus was new to humans. Two days later, CDC laboratory testing confirmed a second infection with this virus in another patient, an 8-year-old living in California about 130 miles away from the first patient who was tested as part of an influenza surveillance project. There was no known connection between the two patients. Laboratory analysis at CDC determined that the viruses obtained from these two patients were very similar to each other, and different from any other influenza viruses previously seen either in humans or animals. Testing showed that these two viruses were resistant to the two antiviral drugs amantadine and rimantadine, but susceptible to the antiviral drugs oseltamivir and zanamivir. CDC began an immediate investigation into the situation in coordination with state and local animal and human health officials in California.

The cases of 2009 H1N1 flu in California occurred in the context of sporadic reports of human infection with North American-lineage swine influenza viruses in the United States, most often associated with close contact with infected pigs. (During December 2005 – January 2009, 12 cases of human infection with swine influenza were reported; five of these 12 cases occurred in patients who had direct exposure to pigs, six patients reported being near pigs, and the source of infection in one case was unknown). Human-to-human spread swine influenza viruses had been rarely documented and had not been known to result in widespread community outbreaks among people. In mid-April of 2009, however, the detection of two patients infected with swine origin flu viruses 130 miles apart, raised concern that a novel swine-origin influenza virus had made its way into the human population and was spreading among people.

By April 21, 2009, CDC had begun working to develop a virus that could be used to make vaccine to protect against this new virus (called a candidate vaccine virus). There are many steps involved with producing a vaccine – the first step is getting a good high yield vaccine virus. A high-yield vaccine virus is a sample of the virus that is used to grow the virus in mass quantities in chicken eggs. Once the virus is grown in mass quantities, the virus particles are then purified to make vaccine. Recognizing that 2009 H1N1 was a new flu virus – and, like all flu viruses, unpredictable - CDC simultaneously pursued multiple scientific methods to create a high-yield virus. A virus isolated at CDC, (called A/California/07/2009) was eventually chosen to be the vaccine virus used to make vaccine. CDC sent the vaccine virus to vaccine manufacturing companies so that they could begin vaccine production, in the event that the U.S. government should decide a vaccine was necessary.

World Braces for Possible Pandemic

On Saturday, April 25, 2009, under the rules of the International Health Regulations, the Director-General of WHO declared the 2009 H1N1 outbreak a Public Health Emergency of International ConcernExternal Web Site Icon and recommended that countries intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia. Also on April 25, 2009, New York City officials reported an investigation into a cluster of influenza-like illness in a high school, and CDC testing confirmed two cases of 2009 H1N1 influenza infection in Kansas, and another case in Ohio shortly after.

On April 26, 2009, the United States Government determined that a public health emergency existed nationwide; CDC’s Strategic National Stockpile (SNS) began releasing 25% of the supplies in the stockpile that could be used to protect and treat influenza. This included 11 million regimens of antiviral drugs, and personal protective equipment including over 39 million respiratory protection devices (masks and respirators), gowns, gloves and face shields, to states (allocations were based on each state’s population).

As part of the nation’s pre-pandemic planning efforts, by April 2009 the Federal Government had purchased 50 million treatment courses of antiviral drugs – oseltamivir and zanamivir – for the SNS, and states had purchased 23 million antiviral regimens. After the determination of the public health emergency, FDA also took action to expand possible usage of antiviral drugs oseltamivir and zanamivir by issuing Emergency Use Authorizations (EUAs).

On April 27, the WHO Director-General raised the level of influenza pandemic alert from phase 3 to phase 4External Web Site Icon, based primarily on epidemiological data demonstrating human-to-human transmission and the ability of the virus to cause community-level outbreaks. Based on reports of widespread influenza-like-illness and many severe illnesses and deaths in Mexico, CDC issued a travel health warning recommending that United States travelers postpone all non-essential travel to Mexico. As in past influenza seasons, CDC urged the public and especially those people at highest risk of influenza-related complications, to protect themselves by taking antiviral drugs early in their illness when recommended by their doctor; CDC also advised that everyone take every day preventive actions like covering coughs and sneezes and staying home from work and school when ill to help reduce the spread of illness.

On April 29, 2009 WHO raised the influenza pandemic alert from phase 4 to phase 5External Web Site Icon, signaling that a pandemic was imminent, and requested that all countries immediately activate their pandemic preparedness plans and be on high alert for unusual outbreaks of influenza-like illness and severe pneumonia. The U.S. Government was already implementing its pandemic response plan. CDC continued to post and update guidance for states, clinicians, laboratories, schools, partners and the public on topics ranging from the non-pharmaceutical measures communities could take to limit spread of disease, to how to evaluate a patient for possible infection with 2009 H1N1 influenza, to how to care for children who might be sick with 2009 H1N1 influenza.

As the outbreak spread, CDC began receiving reports of school closures and implementation of community-level social distancing measures meant to slow the spread of disease. School administrators and public health officials were following their pandemic plans and doing everything they could to slow the spread of illness. (Social distancing measures are meant to increase distance between people. Measures include staying home when ill unless to seek medical care, avoiding large gatherings, telecommuting, and implementing school closures).

A Pandemic is Declared

On June 11, 2009, WHO signaled that a global pandemic of 2009 H1N1 influenza was underwayExternal Web Site Icon by further raising the worldwide pandemic alert level to Phase 6External Web Site IconExternal Web Site Icon. That day, CDC held its first press conference with the new CDC Director Thomas Frieden, MD, MPH. The press conference had a total of 2,355 participants. At the time, more than 70 countries had reported cases of 2009 H1N1 infection, and community level outbreaks of 2009 H1N1 were ongoing in multiple parts of the world. The WHO decision to raise the pandemic alert level to Phase 6 was a reflection of spread of the virus in other parts of the world and not a reflection of any change in the 2009 H1N1 influenza virus or associated illness. To date, most people in the United States who had become ill with 2009 H1N1 influenza had not become seriously ill and had recovered without hospitalization.

After the WHO declaration of a pandemic on June 11, the 2009 H1N1 virus continued to spread and the number of countries reporting cases of 2009 H1N1 nearly doubled from mid-June 2009 to early July 2009. Significant levels of 2009 H1N1 illness continued, with localized and in some cases intense outbreaks occurring. By June 19, 2009, all 50 states in the United States, the District of Columbia, Puerto Rico, and the U.S. Virgin Islands had reported cases of 2009 H1N1 infection. The United States continued to report the largest number of 2009 H1N1 cases of any country worldwide, although most people who became ill recovered without requiring medical treatment. By late June more than 30 summer camps in the U.S. had reported outbreaks of 2009 H1N1 influenza illness, and CDC released guidance for day and residential camps to reduce the spread of influenza. At the June 25, 2009 Advisory Committee on Immunization Practices Meeting Adobe PDF file, CDC estimated that at least 1 million cases of 2009 H1N1 influenza had occurred in the United States.

In early July, 2009, three 2009 H1N1 influenza viruses that were resistant to the antiviral drug oseltamivir were detected in three countries. (Antiviral resistance is when a virus changes in such a way that the antiviral drug is less effective in treating or preventing illnesses caused by the virus.) CDC and WHO partners continued to conduct surveillance for antiviral resistance, although instances of antiviral resistance continued to be detected very rarely.

Also in July 2009, CDC reported findings in the MMWR that indicated a striking prevalence of obesity in intensive care patients who were confirmed to have 2009 H1N1 influenza. Throughout the pandemic, CDC would continue to examine the relationship between 2009 H1N1 influenza, obesity, severe disease and other underlying risk factors.




The 2009 flu pandemic or swine flu was an influenza pandemic that lasted from early 2009 to late 2010, and the second of the two pandemics involving H1N1 influenza virus (the first of them being the 1918–1920 Spanish flu pandemic), albeit a new strain.

It is estimated that 11–21% of the then global population (of about 6.8 billion), or around 700 million–1.4 billion people contracted the illness — more in absolute terms than the Spanish flu pandemic.

However, with about 150,000–575,000 fatalities, it had a much lower case fatality rate of 0.01-0.08%.

Unlike most strains of influenza, H1N1 does not disproportionately infect adults older than 60 years; this was an unusual and characteristic feature of the H1N1 pandemic. Even in the case of previously very healthy people, a small percentage develop pneumonia or acute respiratory distress syndrome (ARDS). This manifests itself as increased breathing difficulty and typically occurs three to six days after initial onset of flu symptoms.

The pneumonia caused by flu can be either direct viral pneumonia or a secondary bacterial pneumonia. In fact, a November 2009 New England Journal of Medicine article recommended that flu patients whose chest X-ray indicates pneumonia receive both antivirals and antibiotics. In particular, it is a warning sign if a child (and presumably an adult) seems to be getting better and then relapses with high fever, as this relapse may be bacterial pneumonia.

Initially called an "outbreak", widespread H1N1 infection was first recognized in the state of Veracruz, Mexico, with evidence that the virus had been present for months before it was officially called an "epidemic".

The Mexican government closed most of Mexico City's public and private facilities in an attempt to contain the spread of the virus; however, it continued to spread globally, and clinics in some areas were overwhelmed by infected people.

The new virus was first isolated in late April by American and Canadian laboratories from samples taken from people with flu in Mexico, Southern California and Texas. Soon the earliest known human case was traced to a case from 9 March in a 5-year-old boy in La Gloria, Mexico, a rural town in Veracruz.

In late April the World Health Organization (WHO) declared its first ever "public health emergency of international concern," or PHEIC, and in June, the WHO and the U.S. CDC stopped counting cases and declared the outbreak a pandemic.

The Mexican government closed most of Mexico City's public and private facilities in an attempt to contain the spread of the virus; however, it continued to spread globally, and clinics in some areas were overwhelmed by infected people.

By 19 November 2009, doses of vaccine had been administered in over 16 countries. A 2009 review by the U.S. National Institutes of Health (NIH) concluded that the 2009 H1N1 vaccine has a safety profile similar to that of seasonal vaccine.

U.S. government officials were especially concerned about schools because the H1N1 flu virus appears to disproportionately affect young and school-age people, between six months and 24 years of age.[105] The H1N1 outbreak led to numerous precautionary school closures in some areas. Rather than closing schools, the CDC recommended that students and school workers with flu symptoms should stay home for either seven days total, or until 24 hours after symptoms subsided, whichever was longer.[106] The CDC also recommended that colleges should consider suspending fall 2009 classes if the virus began to cause severe illness in a significantly larger share of students than the previous spring. They also urged schools to suspend rules, such as penalties for late papers or missed classes or requirements for a doctor's note, to enforce "self-isolation" and prevent students from venturing out while ill;[107] schools were advised to set aside a room for people developing flu-like symptoms while they waited to go home and to have ill students or staff and those caring for them use face masks

More from that page:

United States

The new strain was first identified by the CDC in two children, neither of whom had been in contact with pigs. The first case, from San Diego County, California, was confirmed from clinical specimens (nasopharyngeal swab) examined by the CDC on 14 April 2009. A second case, from nearby Imperial County, California, was confirmed on 17 April. The patient in the first confirmed case had flu symptoms including fever and cough on clinical examination on 30 March, and the second on 28 March.

The first confirmed H1N1/09 pandemic flu death, which occurred at Texas Children's Hospital in Houston, Texas, was of a toddler from Mexico City who was visiting family in Brownsville, Texas, before being air-lifted to Houston for treatment. The Infectious Diseases Society of America estimated that the total number of deaths in the U.S. was 12,469.

Note that this figure (12,469 deaths) is not consistent with the total of 3,642 deaths for all of North America given in the table above (figures from the European Centre for Disease Prevention and Control).





The 2019-20 Unites States flu season caused, as of March 2020, infections among 34 million people, resulting in 350,000 hospitalizations and 20,000 deaths.


The 2019–20 coronavirus pandemic is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The virus was first reported in Wuhan, Hubei, China, in December 2019.[5][6] On 11 March 2020, the World Health Organization declared the outbreak a pandemic.[7] As of 12 March 2020, over 130,000 cases have been confirmed in more than 120 countries and territories, with major outbreaks in mainland China, Italy, South Korea, and Iran.[3] More than 4,900 people have died from the disease and 68,000 have recovered.[4]

The virus spreads between people in a way similar to influenza, via respiratory droplets from coughing.[8][9][10] The time between exposure and symptom onset is typically five days, but may range from two to fourteen days.[10][11] Symptoms are most often fever, cough, and shortness of breath.[10][11] Complications may include pneumonia and acute respiratory distress syndrome. There is currently no vaccine or specific antiviral treatment, but research is ongoing. Efforts are aimed at managing symptoms and supportive therapy. Recommended preventive measures include handwashing, maintaining distance from other people (particularly those who are sick), and monitoring and self-isolation for fourteen days for people who suspect they are infected.


A few things are new this season:

Flu vaccines are updated to better match viruses expected to be circulating in the United States.

The A(H1N1)pdm09 vaccine component was updated from an A/Michigan/45/2015 (H1N1)pdm09-like virus to an A/Brisbane/02/2018 (H1N1)pdm09-like virus.

The A(H3N2) vaccine component was updated from an A/Singapore/INFIMH-16-0019/2016 A(H3N2)-like virus to an A/Kansas/14/2017 (H3N2)-like virus.

Both B/Victoria and B/Yamagata virus components from the 2018-2019 flu vaccine remain the same for the 2019-2020 flu vaccine.

What viruses will the 2019-2020 flu vaccines protect against?

There are many different flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated as needed to match circulating flu viruses. Flu vaccines protect against the three or four viruses (depending on the vaccine) that research suggests will be most common. For 2019-2020, trivalent (three-component) vaccines are recommended to contain:

  • A/Brisbane/02/2018 (H1N1)pdm09-like virus (updated)
  • A/Kansas/14/2017 (H3N2)-like virus (updated)
  • B/Colorado/06/2017-like (Victoria lineage) virus

Quadrivalent (four-component) vaccines, which protect against a second lineage of B viruses, are recommended to contain:

  • the three recommended viruses above, plus B/Phuket/3073/2013-like (Yamagata lineage) virus.

In the meantime, laboratory data can provide some insight into how well vaccines might work. The most helpful data for this is the antigenic characterization data, which are updated weekly in FluView. Limited antigenic data on recently circulating viruses are available at this point in the season, and the data suggest similarity of the circulating influenza A(H1N1)pdm09 and B/Yamagata viruses tested so far to the vaccine viruses. However, the influenza B/Victoria and A(H3N2) viruses that have been tested show some reduced similarity to the vaccine viruses. Again, at this point in the flu season, the antigenic data are limited and can only give early insights into how well vaccines might work. More information about how CDC antigenically characterizes flu viruses is available, and more complete antigenic data will be available in the coming weeks.


I understand why people choose this field of medicine because it seems like a fascinating area to study.