Best way to protect infants from influenza is to vaccinate rest of the family

A University of Sydney study has found the best way to protect children under six months of age from influenza, the most vulnerable of the population to the condition, is to vaccinate the rest of the family.

Data from the research is being presented at the International Congress of Pediatrics, which commences in Melbourne tomorrow. This is the first time the event has been held in Australia.

The study, by the University’s Paediatric Active Enhanced Disease Surveillance (PAEDS) unit, included infants under six months old admitted with laboratory-confirmed influenza to The Children's Hospital at Westmead (CHW) during the Swine Flu pandemic in 2009.

Of 32 infants aged under six months admitted to the hospital with influenza, 28 per cent developed serious complications, 22 per cent developed pneumonia and 16 per cent were admitted to the Intensive Care Unit. Of the infants, 57 per cent had ongoing respiratory illness after being released from hospital, while 21 per cent re-presented to the Emergency Department within six months of their admission with flu.

The study identified a further worrying trend – just 14 per cent of their mothers had been vaccinated against seasonal influenza.

Paper senior author, Professor Elizabeth Elliott, said the three main risk factors documented in the study were exposure to cigarette smoking, household crowding and low rates of household vaccination against influenza.

“The biggest risk factor we documented was close contact with other (unvaccinated) young children in the household, contributing to 46 per cent of cases,” she said.

“The other significant risk factor was that many children were living with at least one smoker in the household, contributing to 36 percent of cases.”

The study authors noted the number of persons per household in the afflicted children was double the state average, so overcrowding was also  evident in children contracting the disease.

“Our study has identified new and significant data relating to influenza in infants under six months of age and suggests that disease and complications in this most vulnerable of groups could be reduced by optimising vaccination rates in the household and minimising exposure to other infected individuals, cigarette smoke and overcrowding,” Professor Elliott said.

“Infants under six months old are particularly susceptible to severe influenza illness, they have no immunity to the disease and they are ineligible for vaccination.

“Young infants aged <6 months accounted for about one-third of influenza admissions to The Children's Hospital at Westmead in 2007, so this is a particularly vulnerable group.”

Paper co-author, Associate Professor Yvonne Zurynski said children in child care settings had the highest rates of influenza, with annual rates between 20 and 30 per cent of the age group being affected.

“Children in childcare settings are efficient transmitters of influenza to other family members including their much younger infant siblings who have no immunity. There is a need, therefore, for much more effective prevention strategies in this group.

“Our message to parents is please vaccinate all of your household against seasonal influenza in order to protect the youngest and most vulnerable in your family. Don’t forget that the influenza vaccine is recommended for pregnant women too.”