Within the past one hundred years, four pandemics have resulted from the emergence of a novel influenza strain for which humans possessed little or no immunity:
– the H1N1 Spanish flu (1918),
– the H2N2 Asian flu (1957),
– the H3N2 Hong Kong flu (1968), and
– the H1N1 swine flu (2009).
Most of this section is taken from the December 2016 Journal of Pathogens. The article was titled – “Reviewing the History of Pandemic Influenza: Understanding Patterns of Emergence and Transmission” by Patrick R. Saunders-Hastings and Daniel Krewski.
So on March 17, 2009, the first case of a novel H1N1 influenza virus infection, also known as swine flu, was documented in Mexico. It rapidly spread throughout Mexico and the US and was declared a full pandemic by the WHO on June 11, 2009. Swine flu circulated around the world in two waves until August 10, 2010, when the WHO officially declared the pandemic over.
The 2009 Swine flu (H1 N1) virus was the last pandemic declared by the WHO before the coronavirus (COVID-19). It originated in North American pigs, but spread to a few California and Texas children, and exploded in Mexico in March of that year. Fortunately, the 2009 H1N1 strain was not especially lethal, but it did prove unusually contagious as it caused one of the largest pandemics in modern history.
It is estimated that 700 million to 1.4 billion people contracted the illness which resulted in 150,000 to 575,000 fatalities worldwide. Do bear in mind that in 2009, many governments could not test everybody for this specific flu strain, so they just assumed that ‘flu-like’ symptoms were H1N1 (Swine) Flu.
There is no commonly accepted metric to quantify the economic impact. On the low end, the 2009 H1N1, aka swine flu, outbreak had an estimated economic impact of $55 billion. On the higher end of estimates, the 2009 H1N1 virus which is accepted as being relatively weak, is estimated to have wiped 0.5 to 1.5 per cent off global GDP.
The pandemic also caused societal disruption and a substantial economic burden, which was documented more comprehensively than for past influenza pandemics. However, the total global impact of the pandemic is not well understood. First, direct costs related to treatment, with respect to drugs, outpatient visits, and hospitalizations, were high. In Canada, total costs have been estimated at around CAD$2 billion, with the care of hospitalized patients alone estimated to be close to CAD$200 million, as the cost of hospitalization for each H1N1-infected patient averaged about $11,000. Emergency department visits are estimated to have resulted in costs of another $50 million.
Overall, estimates of economic losses range from 0.5%–1.5% of GDP in affected countries. Such calculations, however, tend to underestimate other, often longer-lasting impacts related infection prevention efforts, such as school closures, lost productivity from work absenteeism, shifts in consumer habits, and reduced tourism. For example, although reactive school closures were implemented in many countries due to the high transmission rate in children, associated costs are difficult to calculate, as such action also leads to work absenteeism and lost productivity.
One study of the impact of school closure on households in New York City found that, in 17% of households, at least one adult had to miss work because of the closures. Though estimates vary depending on the size of the affected population and duration of closure, school closures have been estimated to cost from tens to hundreds of millions of dollars. The pandemic also negatively affected global tourism, with airlines reporting losses in the tens of millions. It is difficult, however, to disentangle swine flu’s role in this decline, as the global economic crisis of 2008 was occurring simultaneously.
The response to the 2009 H1N1 pandemic, particularly in North America and Europe, demonstrated a significantly improved level of preparedness relative to past pandemics. This was the result of emergency preparedness efforts catalysed by the earlier SARS outbreak of 2002–2003 and persisting fears surrounding H5N1 avian flu. Containment efforts employed a combination of pharmaceutical and non-pharmaceutical interventions.
In the United Kingdom, for example, an aggressive containment campaign combined school closure and voluntary isolation with antiviral treatment for suspected cases and mass prophylaxis of potential contacts; these interventions helped control the outbreak until more information could be gathered. The swine flu pandemic also marked the first pandemic response combining both vaccination and antiviral use.
In Canada, though an H1N1 vaccine was not approved until about six weeks into the second wave, the largest mass immunization program in the nation’s history was carried out, with the federal government investing $400 million to purchase fifty million doses of the vaccine. High priority groups were the first to receive vaccination, before it was expanded to all groups a few weeks later. Between one third and one half of the population was vaccinated over the remainder of the pandemic.
Vaccination coverage was lower in the United States (with state averages from 12.9% to 38.8%), and much of Europe, with the exception of Norway (45%) and Sweden (59%). Unfortunately, there was little use of antivirals before September 2009, though awareness campaigns targeting primary care providers increased their use to treat patients later in the pandemic.
Non-pharmaceutical measures applied in response to past pandemics were again widely implemented to help contain the pandemic. The most common among these were recommendations for hand hygiene and voluntary isolation of symptomatic individuals. Canada did not recommend school closures to mitigate the pandemic, but did benefit from closures for summer break during the first wave; estimates from Alberta suggest this reduced transmission among children by at least 50%.
Other countries, including the United States, United Kingdom, and Australia, did recommend and implement school closures. While there is uncertainty regarding the effectiveness of these interventions, research suggests strong compliance with, and public acceptance of, these measures.
Another important concern was the observed strain on public health, hospital, and human resources during pandemic peaks. While health systems were generally able to accommodate surges in patient demand, it is likely that an even marginally more severe pandemic would have resulted in harmful service disruption and the need to turn patients away. This was, in part, due to the need for doctors to issue antiviral prescriptions, which has since been addressed by extending this authority to pharmacists.
Overall, the 2009 H1N1 pandemic was a mild, albeit costly, global virus.