A "5-in-1" combination vaccine increases the percentage of children receiving all recommended vaccinations at the scheduled time, reports a study in the February issue of The Pediatric Infectious Disease Journal. The combination vaccine reduces by half the number of days that infants and young children are unprotected against serious infections, according to the new study. The lead author was Laura E. Happe, Pharm.D., MPH, of Xcenda, Palm Harbor, Fla.
The researchers used data from the Georgia Medicaid program to determine how the 5-in-1 combination vaccine affected the timeliness of recommended childhood vaccinations. Approved in 2003, the "DTaP/HepB/IPV" vaccine protects against five different diseases:
• Diphtheria, tetanus, and pertussis (whooping cough)—vaccines against these three diseases are usually given together in a combined "DTaP" vaccine.
• Hepatitis B—infection with the hepatitis B virus can be prevented with the "HepB" vaccine.
• Polio—prevented using the inactivated polio vaccine, "IPV."
The study compared 2,880 Georgia children who received the five-vaccine combination with 2,672 who received the three-vaccine DTaP combination. This comparison group was used because they had a similar "propensity" to be vaccinated. Three shots with the DTaP/HepB/IPV vaccine protect against all five diseases. Children receiving DTaP vaccine would need at least six additional shots of IPV and HepB vaccine to obtain the same protection.
Vaccinations were more timely for children receiving the 5-in-1 combination. On a list of eleven different recommended vaccines, the overall on-time vaccination rate was 66.3 percent for children receiving the DTaP/HepB/IPV vaccine, compared to 60.8 percent for those receiving DTaP vaccine.
By age 2, children receiving the 5-in-1 vaccine had fewer days without all recommended vaccinations: about 30 days on average, compared to 70 days in the DTaP group. Thus children receiving the 5-in-1 vaccine spent less than half as much time at risk of serious infections. The differences remained significant after adjustment for other factors affecting vaccination rates, such as race/ethnicity.
Combination vaccines reduce the number of shots needed while providing the same level of protection against disease. This is an especially important advantage as childhood vaccine recommendations become increasingly complex. On-time vaccination not only reduces the risk of serious infections for the individual child, but also reduces the risk of disease outbreaks in the community.
Unfortunately, only 26 percent of U.S. children receive all recommended vaccinations on time. In Georgia, the rate is even lower—just 15 percent. Although previous studies have shown that combination vaccines increase overall protection rates, the new study is the first to evaluate how they affect the timeliness of childhood vaccinations.
"Use of DTaP/HepB/IPV in this Medicaid population was associated with improved on-time vaccination and fewer undervaccinated days," Happe and coauthors conclude. They believe that using this and other combination vaccines—as currently recommended by the American Academy of Pediatrics and other expert groups—will improve vaccination timeliness. In the long term, this may improve health outcomes by reducing the amount of time that children are "suboptimally protected" against serious infectious diseases.