London, Sep 28 (IANS): Children under six months old with an older sister or brother are more than twice as likely to be admitted to hospital with flu than children who do not have older siblings, says a new research.

Flu can be serious in very young children because it can cause lung infections and breathing difficulties. It can also cause a very high fever, leading to fits called febrile convulsions.

The results showed that among children under six months who had one older sibling, there was around one extra hospital admission for every 1,000 children compared to children who did not have any siblings.

For those with two older siblings, there were two extra hospital admissions for every 1,000 children, the researchers said, in the paper published in the European Respiratory Journal.

"Children are very effective spreaders of respiratory viruses like flu. Our study suggests that older siblings pose a risk of serious infection for their baby sisters and brothers," said lead author Pia Hardelid, lecturer at the University College of London.

Further, the risk was also higher for babies born between July and December, who would be very young at the start of the flu season.

"At the moment there is no vaccine approved for babies under six months. This means we need to look at other ways to minimise the risk of infection," Hardelid said

Thus, if parents get older siblings -- aged two years and older -- vaccinated, it can help bring down serious infections in the babies and young children that are under two, the researchers suggested.

In addition, previous studies have suggested that maternal vaccination during pregnancy can protect young babies from flu infection.

For the study, the researchers included children born in Scotland between October 2007 and April 2015 -- about 400,000 in total.