School-located flu vaccination program reduced infection rates

Decreased influenza rates and improved school attendance can be achieved with influenza vaccination of at least one-quarter of a school’s population, according to recent study findings published in Clinical Infectious Diseases.

Pia S. Pannaraj, MD, MPH, of the division of infectious diseases at Children’s Hospital Los Angeles, and colleagues evaluated 4,455 children aged at least 5 years from eight elementary schools (kindergarten through sixth grade) in two Los Angeles County school districts to determine the effect of school-located influenza vaccination. Four schools were interventions schools and the remaining were controls.

Pia S. Pannaraj

Trivalent and live-attenuated influenza vaccines were offered to participants for free at all intervention schools and were those recommended for the 2010-2011 season. The distributed vaccines matched 94% to 99.8% of all strains circulating throughout the county that year.

Children with contraindications to the live vaccine or whose parents requested vaccine injection received the inactivated trivalent vaccine.

There were 2,368 participants attending intervention schools and 32.7% of those were vaccinated: 16.9% received the trivalent vaccines and 83.1% received LAIV. There was documented receipt of influenza vaccine for 1.6% of participants in the California Immunization Registry. Among control schools, 2.7% of participants had documented immunization in the California Immunization Registry from a community site.

Respiratory swabs were obtained from 20.2% of all participants during the active surveillance period (Jan. 1 to April 15, 2011) for influenza-like illness (ILI). Most commonly, there were two episodes of ILI (n=114), followed by three episodes (n=9) and four episodes (n=2). Forty-seven percent of 1,959 school absences for fever had specimens collected during the surveillance period.

Twenty-one percent of 1,021 respiratory specimens tested were positive for influenza, including 30.9% for influenza A 2009 H1N1; 9.2% for influenza A subtype H3; and 59.9% for influenza B. More than 90% of PCR-confirmed influenza infections were among unvaccinated children.

Compared with control schools, there was a 30.8% reduction in influenza rates for participants attending intervention schools. There was a 67% vaccine effectiveness against PCR-proven influenza among all participants.

“Vaccination of school children is the most effective way to reduce influenza illness each year,” the researchers wrote. “[School-located influenza vaccination] programs allow for increased opportunities for vaccination to confer direct and herd immunity among children that will lead to indirect protection of the community. Public health departments and schools must work together to inform parents and provide organized, efficient [school-located influenza vaccination] programs to reach target vaccination coverage of 50% or greater.”

Manjusha Gaglani, MD, chief of pediatric infectious diseases at Baylor Scott and White Health, wrote that school-located influenza vaccination is safe and effective and can be implemented as a local community outreach program.

“[School-located influenza vaccination] facilitates ongoing collaboration between local health care systems, including hospitals and clinics, nursing schools, local health departments, school districts, parent-teacher organizations, community leadership and health insurance companies, which can help local communities prepare for influenza pandemics and all-hazards,” she wrote.

For more information:

Gaglani M. Clin Infect Dis. 2014;doi:10.1093/cid/ciu344.

Pannaraj PS. Clin Infect Dis. 2014;doi:10.1093/cid/ciu340.

Disclosure: The study was funded in part by the NIH and the Thrasher Foundation Early Career Award.