Influenza Vaccine Protects Obese, Non-Obese Children against Laboratory-Confirmed Influenza
SAN FRANCISCO, CA—A study evaluating whether the influenza vaccine protects against disease in obese children found vaccination did protect obese as well as non-obese children and improved school attendance, results of a study reported at IDWeek 2013.
Among adults hospitalized during the 2009 H1N1 influenza pandemic, obesity (ie, body mass index [BMI] >30) “was associated with increased risk of viral pneumonitis and admission to the intensive care unit,” noted Michael Smit, MD, MSPH, of Children's Hospital Los Angeles, Los Angeles, CA. “Extreme obesity (BMI >40) was associated with greater odds of death.”
However, no data was available on obese children. The study also evaluated whether unvaccinated obese children had higher rates of laboratory-confirmed influenza and absenteeism during influenza season compared to non-obese children.
During the 2010–2011 season, the investigators conducted active surveillance for influenza-like illness on 4455 children from eight elementary schools (kindergarten to grade 6) in Los Angeles County.
“Information collected included age, gender, height, weight, ethnicity, vaccination status, symptoms, and duration of illness,” Dr. Smit reported. “Obesity was defined as BMI ≥95th percentile. Laboratory confirmation with multiplex polymerase chain reaction (PCR) for 12 respiratory viruses was performed on nose and throat swabs collected from children with influenza-like illness.”
Of the 4260 children with BMI data (28% obese, 19.4% overweight, 51%, healthy weight, and 1.6% underweight), respiratory viruses were detected in 36.1% of those children.
Among vaccinated children, rates of PCR-confirmed influenza were similar in obese and non-obese children (1.7 vs. 2.0 per 100 children, P=0.769). In unvaccinated children, rates of PCR-confirmed influenza were higher in obese than non-obese children (6.2 vs. 5.5 per 100 children).
“However, unvaccinated obese children were 3.6 times more likely to have PCR confirmed influenza compared to vaccinated obese children (6.2 vs. 1.7 per 100 children, P=0.003) and miss about the same number of school days (4.6 vs. 4.1 per 100 school days, P<0.001).