Targeting vaccines to school-age children and their parents could help manage potential outbreaks of swine and seasonal flu and avert worrisome vaccine shortages, researchers suggested on Thursday.
The study in the August 21 issue of the journal Science comes as the Northern Hemisphere braces for the start of its influenza season in the coming months, while deaths from swine flu mount in countries where it is winter.
The approach runs counter to typical recommendations to battle seasonal flu, which urge the vaccination of children under five as well as all people over the age of 50, noted study co-author Jan Medlock, a mathematician at Clemson University in South Carolina.
But "vaccines would be better used to prevent transmission within schools and out to parents, who then spread the flu to the rest of the population," Medlock said.
His research used a mathematical model to demonstrate cases of flu spreading in which limited vaccine doses were given to school-aged children and adults age 30-39 -- parents in contact with the students.
Looking at the influenza pandemics of 1918 and 1957, researchers determined that even with just 63 million doses of vaccine, they could be given first to children 5-19, the group in which the greatest amount of spreading takes place, and adults 30-39, most often infected by their children.
Following the traditional protocols, the United States uses more than 80 million doses of seasonal flu vaccine every year to combat influenza, which kills about 36,000 Americans annually.
But faced with the swine flu, or (A)H1N1 global pandemic, which has already killed 1,799 people worldwide according to the World Health Organization, experts have raised concerns about the availability of enough vaccine to administer to at-risk groups.
In July, the Centers for Disease Control (CDC) said children and pregnant women should be among the first to receive a swine flu vaccine, and warned that the total at-risk population would number around 160 million.
Those targets also include caretakers and others in contact with children under six months old, healthcare workers, youths between the ages of six months and 24 years, and adults with underlying medical conditions.
Officials at that time forecast a shortage of vaccines, with only 120 million doses likely to be available by October.
But in August, US health officials issued a more dire warning that only 45 million swine flu doses would be ready by mid-October, with 20 million doses delivered each week thereafter.
The WHO has forecast possible shortages in the production of (A)H1N1 vaccines this year due to the slow growth of the swine-origin (A)H1N1 in chicken eggs.
Unlike seasonal flu, which usually hits elderly people the hardest, the (A)H1N1 virus has mostly infected the young. It emerged in Mexico in April and has since spread to 170 countries.
Deaths from swine flu in Latin America -- the worst-hit region in the world -- rose to more than 1,300 this week after governments added to tolls from the disease.
South America has seen the (A)H1N1 flu spread widely during its southern hemisphere winter. In several countries, it has overtaken ordinary seasonal flu.
And with vaccines against swine flu still more than a month away from being available -- and wealthy countries snapping up all available pre-orders from the big drug companies -- Latin American nations are looking at ignoring patents to produce their own.
Worldwide, there have been 177,457 confirmed cases of swine flu, according to the World Health Organization.
More than two million people have probably been infected by the swine flu virus in the United States, including 7,511 who have been hospitalized and 477 who have died, according to the most recent figures of the Centers for Disease Control and Prevention.