Last updated on April 17, 2014 at 1:21 EDT

2009 Swine Flu Pandemic Death Toll Much Worse Than Originally Believed

June 26, 2012
Image Credit: CDC

Lawrence LeBlond for redOrbit.com

Shortly after the 2009 H1N1 “swine flu” pandemic, health experts from the World Health Organization (WHO) had reported that roughly 18,500 people died from the virus, a finding that is being called into question as researchers now believe the death toll reached more than quarter of a million people, 15 times more than the original estimate.

Publishing their findings in The Lancet Infectious Diseases journal, an international group of epidemiologists and physicians underlined the need for better planning and vaccine distribution to better estimate the global reach of the “swine flu” pandemic.

While the international team of researchers have put the new estimate at 284,500 deaths, they say it could be even higher — as many as 579,000 deaths. The Centers for Disease Control and Prevention (CDC) and the WHO noted that their 2009 low estimate came from only counting deaths confirmed by lab testing. They acknowledged at the time that it was probably a gross underestimate as many people without access to the healthcare system went uncounted, and also because the virus is often undetectable after the victim dies.

Experts said it really wasn´t a surprise that the researchers reported a big increase in estimated deaths from H1N1. In any pandemic, the initial count is usually always based on lab-confirmed tests that typically underestimate the true number of fatalities. The new estimate of 284,500 is a rough median estimate for the actual range of 151,700 to 575,400 possible deaths from swine flu.

The swine flu pandemic, which officially ran from June 2009 to August 2010, caused havoc around the world, sickening perhaps millions of people. The contagion was triggered by a recombination of bird, pig and human viruses and was the first flu pandemic of the 21st century. The rise in sickness prompted several national public-health emergencies worldwide and pushed many countries to stockpile vast amounts of vaccine and antiviral drugs.

In the latest study, researchers confirmed the earlier observations that 80 percent of deaths occurred in people under 65 years of age. Around 30 percent of the victims in that age group were healthy with no underlying risk factors. This was in sharp contrast from seasonal flu, which generally claims the elderly and those who are weak and frail.

Also, nearly 60 percent of the fatalities were likely to have occurred in Southeast Asia and Africa, the researchers noted. The highest mortality rates were in Africa mostly due to an inadequate health infrastructure and the lack of trained medical professionals to aid the sick.

“This study is one of the first to provide a global estimate of deaths caused by the 2009 H1N1 virus,” lead author Fatimah Dawood of the CDC told AFP via email. “Our results also suggest how best to deploy resources. If a vaccine were to become available, we need to make sure it reached the areas where the death toll is likely to be highest.”

“This pandemic really did take an enormous toll,” she added.

And after the pandemic ended, the WHO was criticized for being alarmist about the dangers of H1N1. The Council of Europe accused the agency of causing unjustified scares and a waste of public money as countries scrambled to buy vaccines.

However, the UN agency said the Lancet data validate its response.

“More than 200,000 deaths is not nothing, it is a significant event — especially when you look at the ages of those who died,” Anthony Mounts, a medical epidemiologist at WHO told the Wall Street Journal. “I think the WHO did the right thing” in reacting forcefully to the pandemic.

In raising the estimate on the swine flu pandemic death toll, Dawood and colleagues — from Vietnam, Kenya, New Zealand, Denmark and five other countries — first went to work on estimating the percentage of the population in 12 countries who had come down with H1N1-related symptoms. The team also estimated the proportion of people who died after getting infected, which varied from region to region.

The team then obtained official WHO estimates on how many people in each country die from respiratory-tract infections, which is how swine flu usually kills. All data were combined into a statistical model.

Their findings suggest that anywhere from 150,000 to 575,000 people died from the flu during the first year that the virus circulated in each country. About 70 percent of those cases were respiratory deaths and the rest were cardiovascular deaths.

These estimates and assumptions, however, can introduce errors, critics say. Newly released mortality data from Mexico show that H1N1 killed even more people than even the new study estimated, according to Lone Simonsen of George Washington University School of Public Health, coauthor of a commentary on the study. But on the other hand, estimates of deaths from Japan and Singapore may be too high.

Overall, however, the extreme over- and under-estimates most likely even out, Simonsen noted, making the latest global estimate about right.

Source: Lawrence LeBlond for redOrbit.com