At least one in five were infected in flu pandemic, international study suggests
(Medical Xpress)—At least one in five people in countries for which data are available were infected with influenza during the first year of the 2009 H1N1 pandemic, according to a new study.
The highest rates of infection were in children, with 47 per cent of those aged five to 19 showing signs of having caught the virus. Older people were affected less, with only 11 per cent of people aged 65 or older becoming infected.
The findings come from an international collaboration led by the World Health Organization and Imperial College London, which analysed data from 19 countries, including the UK, US, China and India, to assess the global impact of the 2009 influenza pandemic.
The results, published in the journal Influenza and Other Respiratory Viruses, showed that 20-27 per cent of people studied were infected in the pandemic during the first year of circulation. The researchers believe the incidence of influenza is likely to have been similar in countries where data were not available, meaning that as many as a quarter of the world's population may have been infected.
The study collated results from more than two dozen research studies involving more than 90,000 blood samples collected before, during and after the pandemic. The samples were tested for antibodies produced by the body in response to the specific flu strain that caused the pandemic.
While this study did not set out to look at mortality, the authors also used previously published estimates of pandemic influenza mortality together with mortality estimates that are still in progress, to estimate the proportion of people infected who died from the pandemic virus. Based on an estimate of approximately 200,000 deaths, they suggest that the case fatality ratio was less than 0.02 per cent.
Multiple exposures to previously circulating influenza viruses may have given older people some protection against the strain that emerged in 2009. Blood samples from before the pandemic showed that 14 per cent of people aged 65 or over already had antibodies that reacted to the 2009 strain.
Dr Maria Van Kerkhove, from the Medical Research Council Centre for Outbreak Analysis and Modelling at Imperial College London, one of the lead authors of the study, said: "This study is the result of a combined effort by more than 27 research groups worldwide, who all shared their data and experience with us to help improve our understanding of the impact the pandemic had globally."
Dr Anthony Mounts of the World Health Organization, the senior author, said: "Knowing the proportion of the population infected in different age groups and the proportion of those infected who died will help public health decision-makers plan for and respond to pandemics. This information will be used to quantify severity and develop mathematical models to predict how flu outbreaks spread and what effect different interventions may have."
More information: Van Kerkhove et al. (2012) Estimating age-specific cumulative incidence for the 2009 influenza pandemic: a meta-analysis of A(H1N1)pdm09 serological studies from 19 countries. Influenza and Other Respiratory Viruses DOI: 10.1111/irv.12074 , http://onlinelibrary.wiley.com/doi/10.1111/irv.12074/pdf
Provided by Imperial College London
- Swine flu: Early findings about pandemic potential reported in new study May 11, 2009 | not rated yet | 0
- Flu mortality formula is potentially misleading, say scientists Jul 15, 2009 | not rated yet | 0
- Swine flu kills three in Central Europe Jan 24, 2013 | not rated yet | 0
- Immunity to the pandemic virus A (H1N1): Norway is probably well-prepared for major new outbreaks Aug 24, 2010 | not rated yet | 0
- 1918 and 2009 H1N1 flu probably not spread by birds Jan 19, 2010 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Classical and Quantum Mechanics via Lie algebras
Apr 15, 2011 I'd like to open a discussion thread for version 2 of the draft of my book ''Classical and Quantum Mechanics via Lie algebras'', available online at http://lanl.arxiv.org/abs/0810.1019 , and for the...
- More from Physics Forums - Independent Research
More news stories
As the world prepares for what may be the next pandemic strain of influenza virus, in the H7N9 bird flu, a new UC Irvine study reveals that the 2009 H1N1 swine flu pandemic was deadliest for people under the age of 65, while ...
Diseases, Conditions, Syndromes 6 hours ago | not rated yet | 0
The World Health Organization says the Horn of Africa is experiencing an outbreak of polio with cases confirmed in Kenya and Somalia.
Diseases, Conditions, Syndromes 7 hours ago | not rated yet | 0
A man who had contracted the coronavirus has died in Saudi Arabia, raising the death toll in the kingdom from the SARS-like virus to 17, the health ministry announced on its website on Wednesday.
Diseases, Conditions, Syndromes 7 hours ago | not rated yet | 0
A new approach for immunizing against influenza elicited a more potent immune response and broader protection than the currently licensed seasonal influenza vaccines when tested in mice and ferrets. The vaccine ...
Diseases, Conditions, Syndromes 7 hours ago | not rated yet | 0 |
Patients with underlying heart failure are more likely to experience adverse outcomes from mild hypothyroidism, according to a recent study accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & ...
Diseases, Conditions, Syndromes 9 hours ago | not rated yet | 0
Swiss scientists reveal the mechanism responsible for aging hidden deep within mitochondria—and dramatically slow it down in worms by administering antibiotics to the young.
10 hours ago | 4.8 / 5 (5) | 0 |
Researchers from Queen Mary, University of London have led the largest sequencing study of human disease to date, investigating the genetic basis of six autoimmune diseases.
10 hours ago | 4 / 5 (1) | 0 |
Until now, little was scientifically known about the human potential to cultivate compassion—the emotional state of caring for people who are suffering in a way that motivates altruistic behavior.
7 hours ago | 5 / 5 (2) | 2 |
(HealthDay)—Migraines and depression can each cause a great deal of suffering, but new research indicates the combination of the two may be linked to something else entirely—a smaller brain.
6 hours ago | 5 / 5 (1) | 0 |
In a series of lab experiments designed to unravel the workings of a key enzyme widely considered a possible trigger of rheumatoid arthritis, researchers at Johns Hopkins have found that in the most severe ...
9 hours ago | 5 / 5 (1) | 0 |
Researchers have developed a new drug delivery system that allows inhalation of chemotherapeutic drugs to help treat lung cancer, and in laboratory and animal tests it appears to reduce the systemic damage ...
9 hours ago | not rated yet | 0 |