Pneumococcal Infection Rates Drop, Despite Uneven Childhood Vaccination

Since its addition to the list of routine immunizations in 2000, one childhood vaccine has helped prevent some pneumococcal-related illness, including pneumonia and otitis media.

The percentage of children receiving pneumococcal vaccines, known as PCV7, is rising steadily. However, fewer than half of children receive the immunizations according to the recommended schedule, a new study finds.

The study appears in the January issue of the American Journal of Preventive Medicine and includes an analysis of data from the 2001 to 2004 National Immunization Surveys, comprising more than 85,000 children between 19 months and 35 months old.

Before the introduction of the vaccine, Streptococcus pneumoniae was the leading cause of bacteremia (bacteria in the bloodstream), bacterial meningitis (an infection of spinal cord fluid and the fluid surrounding the brain) and pneumonia in young children in the United States. PCV7 provides some protection against S. pneumoniae bacteria.

Studies have shown small reductions in otitis media-related physician visits, while some studies have found moderate effectiveness against pneumonia. Other studies indicate that the vaccine is highly effective against invasive disease, such as pneumococcal blood infection and meningitis.

We wanted to see how many children received the vaccine according to the appropriate schedule during this time when the disease rates went down very rapidly, said lead study author Pekka Nuorti, MD, of the Centers for Disease Control and Prevention (CDC).

Conducted by the CDC, the annual National Immunization Surveys collect immunization histories after receiving consent from family caregivers during telephone interviews.

According to the analysis, 45.5 percent of children born in 2000 received the first dose of the vaccine by 12 months of age compared with 62.1 percent of children born in 2002. By two years of age, 30.7 percent of children born in 2000 had received all four recommended doses compared with 49 percent of children born in 2002.

Nevertheless, only 15 percent of the first group of children and 24.4 percent of the second group received the immunizations on schedule.

There were problems in the first couple years with lack of vaccine, but overall there have been studies showing incredible success in reducing pneumonia and other invasive pneumococcal disease, said James Cherry, MD, a professor of pediatrics at Mattels Childrens Hospital at UCLA. Cherry was not involved in the study.

Children who did not receive the vaccination on time were more likely to come from low-income households, be African-American or Hispanic, or receive their vaccination from a public health provider.

The largest reductions in pneumococcal disease in children occurred at a time when only 31 to 49 percent were vaccinated in the first three birth cohorts that were eligible to receive the vaccine, Nuorti said. When we look more closely at the children who received all four doses, only one-half received the vaccination on time according to the national recommendations.

Reference: Nuorti JP, et al. Uptake of pneumococcal conjugate vaccine among children in the 1998-2002 United States birth cohorts. Am J Prev Med 34(1), 2008.

Source: Health Behavior Science News