SAN DIEGO – Maternal acceptance of influenza vaccine during pregnancy and postpartum Tdap immunization both increase infant vaccination rates, results from a large single-center study showed.
"The postpartum period may be an optimal time for education of current threats related to vaccine-preventable infection for mothers and infants," lead study author Gina Calarco said in an interview after IDWeek 2012, the combined annual meetings of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association, and the Pediatric Infectious Diseases Society. "Getting obstetricians and pediatricians actively discussing and educating their patients during this critical period appears to benefit both maternal and infant vaccination rates."
Gina Calarco, M.P.H.
Ms. Calarco and her coinvestigators enrolled 900 postpartum women-infant dyads cared for at Shawnee Mission (Kan.) Medical Center in a prospective study intended to evaluate Tdap vaccine acceptance. This particular hospital was targeted as the research site because of its "location in a relatively affluent area with higher education and socioeconomic status and the highest birth rates in the bistate area," explained Ms. Calarco, who led the study during her tenure as infectious disease study coordinator at Children’s Mercy Hospitals and Clinics in Kansas City, Mo. "In past studies this type of demographic has been known to be vaccine hesitant and this is why we chose this facility. We compared maternal acceptance of Tdap to the infant’s 3-month vaccine record to determine if there are any early indicators of vaccine-hesitant parents. Our overall question was to determine if mom declined vaccination of herself, is she more likely to not fully vaccinate her infant, or conversely if a mom accepts Tdap, does that impact her infant’s vaccine status at 3 months of age."
The mean age of the study participants was 28 years, 83% were white, 66% were married, and 67% had private insurance. Ms. Calarco, who is now a clinical project manager with Quintiles in Overland Park, Kan., reported that 597 of the mothers (66%) received Tdap prior to discharge and 269 (30%) declined the vaccine, while 34 (4%) had received Tdap within 2 years and thus were not currently eligible to receive the vaccine prior to discharge.
A total of 757 maternal Tdap and infant vaccine records and 740 maternal influenza and infant vaccine records were available for analysis. The records revealed that mothers who accepted Tdap were 13.5 times more likely to fully immunize their infant than not to do so. In addition, mothers who received the influenza vaccine were 1.85 times more likely to fully immunize their children than were mothers who did not receive the influenza vaccine.
When the researchers adjusted for maternal age, they found that mothers older than 28 years had a 6% per year increase in having a fully vaccinated infant (OR, 1.06) However, the 34 mothers who had Tdap within the previous 2 years were less likely to have a fully vaccinated infant, compared with other mothers in the study (OR, 0.28). "This was surprising in that these women had accepted Tdap for themselves previously yet were not as likely to immunize their infant," Ms. Calarco commented. "We haven’t explored this finding further, but it may be that the education supplied when they received Tdap was too far removed from them vaccinating their infant, or maybe they received a required tetanus booster vaccine due to an accident and this wasn’t as much [of] a choice."
The study was supported by a grant from the Kenneth and Eva Smith Foundation. Ms. Calarco said she had no relevant financial disclosures.