Several analyses of the NIS data are published in a supplement to the May issue of the American Journal of Preventive Medicine . Overall, 73.2 percent of American children received a full series of vaccinations, according to an analysis of NIS data. This was reflected in the finding that children who were fully vaccinated averaged six immunization visits, while children who didn't receive all their shots averaged five visits. Vaccination coverage increased with increasing numbers of visits. In fact, the group of children who had nine visits approached the Healthy People goal, with 89.7 percent receiving all their shots.
Vaccines come with recommended schedules designed to optimize immune response to the shots.
However, doctors may not be taking full advantage of the flexibility of these recommendations, which would allow them and parents various options for completing the vaccinations on time, the researchers say. Others advocate spreading vaccinations over more than the minimum number of visits. The researchers note that while infants could receive as many as five vaccines in one visit, only 3.3 percent of infants do, likely due to the concern that too many shots will overburden the infant's immune system. With the recent addition of four doses of pneumococcal vaccine, however, this will play an increasingly important role in childhood vaccination. Among African-American children, the primary reason for inadequate vaccination coverage does not appear to be too few visits, according to another study using NIS data.