Timely Pertussis Vaccination Could Save Infant Lives

By Will Boggs MD

May 05, 2015

NEW YORK (Reuters Health) - Timely infant and maternal pertussis vaccination could reduce infant mortality from the disease, according to the U.S. Centers for Disease Control and Prevention (CDC).

"When this study was done, using data from 1991-2008, we did not have a recommendation for routine maternal immunization," Dr. Tejpratap S.P. Tiwari from the CDC, Atlanta, Georgia, told Reuters Health by email.

"But now we recommend vaccinating pregnant women with Tdap (tetanus, diphtheria, pertussis) during the third trimester of each pregnancy to pass protective antibodies to infants as a strategy to prevent infant pertussis deaths."

"On-time scheduling of routine DTaP (diphtheria, tetanus, and pertussis) vaccination at the two-month visit will further minimize or prevent additional deaths in infants," Dr. Tiwari added.

In the U.S., DTaP is approved for children under age 7. Tdap, which has a reduced dose of the diphtheria and pertussis vaccines, is approved for adolescents and adults ages 11 to 64.

The American Committee on Immunization Practices (ACIP) recommends that children receive five doses of DTaP vaccine at 2, 4, 6, and 18 months and at 4 to 6 years of age. The first dose can be administered as early as 6 weeks of age, particularly during outbreaks.

Studies have established the protective efficacy of pertussis-containing vaccines against pertussis, hospitalization, and pertussis complications in infants, but the protective role of the vaccines against death has not been reported.

Dr. Tiwari and colleagues used data from the National Notifiable Diseases Surveillance System to evaluate the role of at least one vaccination in preventing death, hospitalizations, and complications among infants aged at least 6 weeks, as well as the risk markers for fatal pertussis among infants younger than 6 weeks who were age-ineligible for vaccination.

Among infants younger than 42 days, the risk of a fatal outcome decreased with increasing weeks of age, but increased for infants with Hispanic ethnicity. Results were similar for infants aged 42 days and older.

Among age-eligible infants, receipt of at least one pertussis vaccine dose was associated with a 72% decrease in the relative risk of fatal pertussis, after adjusting for age at onset, Hispanic ethnicity, race, and treatment with a recommended antibiotic.

The researchers observed a similar protective effective in infants aged 56 to 90 days, according to the May 4 Pediatrics online report.

Receipt of at least one pertussis vaccine dose was also associated with a 31% reduction in the risk of hospitalization and a 20% reduction in the risk of pneumonia. Vaccination did not appear to protect against seizures or encephalopathy.

Vaccination of all infants at week 8 of life would have reduced infant pertussis deaths in this cohort by 16% (including 72% of those that occurred after age 8 weeks). Earlier vaccination, at week 6 of life, would have averted an estimated 26% of infant pertussis deaths (including 74% of those that occurred after age 42 days).

"Children who haven't received DTaP vaccines are at least eight times more likely to get pertussis than children who received all five recommended doses of DTaP," Dr. Tiwari said. "Furthermore, immunity from vaccination decreases over time and herd immunity cannot be relied upon to protect susceptible children. This further emphasizes the importance of protecting very young infants by vaccinating pregnant women with Tdap during the third trimester of each pregnancy and that infants receive on-time vaccination with DTaP vaccine."

"Strategies should be prioritized to maximize efforts to protect young infants younger than 8 weeks old, who are at greatest risk of death due to pertussis," Dr. Tiwari concluded. "It is important to reinforce the recent recommendation for Tdap use during each pregnancy to pass early protection to infants before birth (see www.cdc.gov/pertussis/pregnant)."

The CDC funded this study and employs the authors.

SOURCE: http://bit.ly/1QfXHC7

Pediatrics 2015.

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