Flu vaccines work and can successfully halt pandemics, according to a major analysis reported today.
Researchers attributes the development of a vaccine to the halting of the so-called "swine flu" pandemic in 2009.
The study also finds the effectiveness of vaccines reduces with the age of patients.
This finding will reinforce the new policy of vaccinating children against flu.
The project involved researchers in Bosnia, Japan, and at the Erasmus Medical Centre, the Netherlands and the universities of Nottingham and Bristol in the UK.
During the A(H1N1)pdm09 pandemic about 61 million people are thought to have been infected worldwide. The virus affected children and pregnant women to an unusual extent.
The new study involved analysis of 38 pieces of research published since 2011 and in total analysing the impact of the vaccines on populations totalling more than seven million. 23 of these publications were suitable for metanalysis.
Swine flu emerged in March 2009 and was declared a pandemic in June 2009. Vaccination began in September 2009.
Researcher Professor Jonathan Van Tam, from Nottingham, said: “We found that the vaccines produced against the swine flu pandemic in 2009 were very effective in both preventing influenza infection and reducing the chances of hospital admission due to flu.
"This is all very encouraging in case we encounter a future pandemic, perhaps one that is more severe."
He added: "If we can speed up vaccine production times, we would have a very effective strategy to reduce the impact of a future flu pandemic.”
* A new bird flu virus is highly infectious – but probably only to birds, European experts have warned.
Scientists have found significant mutations in the new A(H7N9) virus, which has proved able to infect humans, according to the European Centre for Disease prevention and Control.
These mutations make it highly pathogenic in poultry but there is little evidence that it is infectious between humans, according to the ECDC analysis.
The virus was first found last month in a patient in Taiwan and in two patients in Guangdong, China. Its mutations were found to be in the haemagglutinin gene.
But it is still unclear whether it will replace other A(H7N9) viruses in poultry – and there have been no reports of further human cases, the ECDC reported. During this winter’s outbreak some 460 human patients have been found with A(H7N9) virus infection but only three infected by the new mutated virus.
The centre says the findings heighten the need for European travellers to be aware of the risk of bird flu infection. It says travellers should avoid visiting live poultry markets.
Any traveller who develops flu symptoms after a visit to China should visit a doctor and explain they have been in affected areas, the ECDC says.
It states: "The possibility of humans infected with A(H7N9) returning to the EU/EEA cannot be excluded."
Effectiveness of 2009 Pandemic Influenza A(H1N1) Vaccines: A Systematic Review and Meta-Analysis Vaccine 14 March 2017 [abstract]
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