Shortening the time between the start of a severe flu outbreak and mass vaccination saves lives and money, suggests new research.
Traditional methods, such as washing hands and wearing face masks, are also effective at controlling an outbreak until vaccines are made available, researchers said.
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"We saw what happened in 2009 and we wanted to take a look at if the response was similar to that in a more severe pandemic episode how prepared are we," said Dr Nayer Khazeni, the study's lead author from the Stanford University School of Medicine in California.
Increases in infections, deaths and costs
The World Health Organisation declared in June 2009 that an outbreak of the H1N1 influenza virus qualified as a pandemic, which is when a virus circulates around the globe and most people do not have immunity against it. The strain was referred to as "swine flu" early on.
Khazeni and her fellow researchers write in the Annals of Internal Medicine that vaccination against H1N1 did not start until about nine months after the outbreak began.
In a previous study, they found that every four-week delay in vaccinations during that outbreak led to significant increases in infections, deaths and costs.
The researchers used a computer model for the new study to estimate what those figures might look like in a city like New York during a more severe flu pandemic, depending on when the first 30% of the population became vaccinated.
The pandemic used for the computer model was crafted like the 1918 Spanish flu pandemic, which killed an estimated 30 to 50 million people globally, including 675 000 in the US.
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Healthcare costs would fall
The flu virus used in the model also borrowed traits from two emerging bird flu viruses from Asia and the Middle East, H7N9 and H5N1
The researchers estimated that each person with the flu would infect about two more.
About 48 250 people would die if it took a full year from the start of the outbreak for 30% of a city with about 8 million people to get vaccinated, according to the model.
About 45 890 people would die if vaccination took nine months – as it did during the 2009 outbreak. Deaths would fall to about 34 480 if vaccination was pushed up to four months.
Healthcare costs would also fall by about $100 million city-wide if widespread vaccination were moved from nine months to four months, or almost $4 billion nationally.
The researchers note that the current process to create flu vaccines takes about five months under the best circumstances, however. New technology that does not use eggs to develop a vaccine may allow for shorter production times, they write.
"These figures may help policymakers decide what scenarios warrant a concerted effort between vaccine manufacturers and the government to speed production and administration," they add.
If speeding up vaccine production is not possible, the researchers also found that non-drug techniques like wearing masks, washing hands and staying in may control the outbreak until a vaccine is ready.
"I think that's a really encouraging finding," Khazeni said.
Dr Mark Mulligan, executive director of the Hope Clinic of the Emory Vaccine Centre in Atlanta, told Reuters Health that people should know the best defence against the flu is prevention.
"That weapon – although not perfect – is the vaccine," he said. "People should be vaccinated annually and when there is a pandemic we want to get as many people vaccinated as possible."
Mulligan, who was not involved with the new study, also said it's important that people follow the advice that's already known, such as washing hands and coughing into the crook of the arm.
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