Infants and toddlers given two doses of the influenza vaccine are less likely to contract flu, pneumonia and influenza-like illnesses, but one dose does not appear to have any effect, according to findings published in the Journal of Pediatrics.
Dr. Mandy A. Allison, of the University of Utah, Salt Lake City, and colleagues examined the effectiveness of the currently recommended two-dose influenza vaccine for young children, as well as the effect of one dose of the vaccine, in preventing visits to the doctor for influenza-like illness.
They analyzed data for 5193 healthy children between the ages of 6 and 21 months who were seen at five Denver pediatric practices during the 2003-2004 flu season. The average age of the children was 15.5 months.
The kids were defined as being partially vaccinated if they had one shot more than 14 days before the first influenza-like illness visit, and fully vaccinated if they had the full two shots more than 14 days before the first visit.
Overall, 28 percent of the children were seen for influenza-like illness and 5 percent had a visit for pneumonia/influenza.
Full vaccination was 69 percent effective in preventing office visits for influenza-like illness and 87 percent effective in preventing office visits for pneumonia/influenza. This is comparable to the effectiveness of the vaccine in adults.
However, the partially vaccinated children were just as likely to be seen for influenza-like illness or pneumonia/influenza as were unvaccinated children.
The results confirm the effectiveness of two doses of flu vaccine and "lend support to the recommendation for universal immunization against influenza in 6- to 23-month-old children," Allison's team concludes.