October 04, 2017
2 min read

Older siblings significantly increased influenza risk for infants, toddlers

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The presence of an older sibling drastically increased the risk of influenza-related hospitalization among children aged younger than 2 years, according to a study published in The European Respiratory Journal.

Additionally, infants younger than 6 months with older siblings were more than twice as likely to be hospitalized with influenza compared to other children.

“Flu can be a serious infection in very young children, but at the moment, there is no vaccine approved for babies under 6 months,” Pia Hardelid, PhD, MSc, a lecturer in epidemiology at the UCL Great Ormond Street Institute of Child Health in London, said in a press release. “This means we need to look at other ways to minimize the risk of infection.”

To analyze the risk factors associated with hospitalization in children younger than 2 years as a result of influenza and to guide future pediatric vaccination programs, the researchers conducted a study in which all singleton births in Scotland between October 2007 and April 2015 were linked to data concerning hospitals administration and influenza lab reports. Birth and family risk of hospital admissions from influenza were calculated using Cox proportional hazard models.

Of the 424,048 children who were hospitalized between 2007 and 2015, 1,115 were related to an influenza diagnosis. Most these children were not included in high-risk groups and were full term (85.1%); however, children, especially those younger than 6 months. were at an increased risk of contracting influenza if they had an older sibling (HR for second- vs. first-born child = 2.02, 95% CI, 1.52-2.69).

Other risk factors for influenza included mothers being younger than 30 years and birth during autumn months (age: younger than 6 years).

“There is not much parents can do about the time of year their baby is born, but women can also help reduce the risk of serious flu for their newborns by taking up the invitation to have a vaccine when they are still pregnant,” Hardelid said in the release. “There is some evidence that maternal vaccination during pregnancy can protect young babies from flu infection.” – by Katherine Bortz

Disclosure: The authors report no relevant financial disclosures.