Abstract by Pablo Zubeldia
Estimation of the Effects of Vaccination using a Natural Experiment
Craig Scoville, MD, PhD; Glenn Leavitt, DO; Edward Evans, MD; Jordan DiReda; Maritza Rosales; Dennis Tolley, PhD; Pablo Zubeldia.
Preeclampsia (PE) is a dangerous autoimmune disease affecting 3-8% of all pregnancies. A small pilot study done 5 years ago indicated that pregnant females who had low anti-tetanus antibodies had a higher likelihood of getting PE prior to delivery. Due to a whooping cough scare in southern Idaho in 2011-2012, some physicians started vaccinating women at 28 weeks gestation with Tdap. Prior to the scare, mothers were vaccinated at delivery. We found in the greater Idaho Falls area one clinic that still vaccinated at delivery and one that vaccinated at 28 weeks gestation. Thus, by chance a natural experiment took place between these two clinics. We found 465 records from the first clinic and 354 records from the second clinic for the year 2015. We compared their PE rates. An additional analysis was performed on the second clinic by reviewing medical records from 2009 to 2011 to determine if there was a within-clinic change in the PE rates before and after initiation of the Tdap vaccination policy. Results of these two analyses are presented.