title: Mitigating Prenatal Zika Virus Infection in the Americas.
abstract: BACKGROUND
  Because of the risk for Zika virus infection in the Americas and the links between infection and microcephaly, other serious neurologic conditions, and fetal death, health ministries across the region have advised women to delay pregnancy. However, the effectiveness of this policy in reducing prenatal Zika virus infection has yet to be quantified.
  
  
  OBJECTIVE
  To evaluate the effectiveness of pregnancy-delay policies on the incidence and prevalence of prenatal Zika virus infection.
  
  
  METHODS
  Vector-borne Zika virus transmission model fitted to epidemiologic data from 2015 to 2016 on Zika virus infection in Colombia.
  
  
  METHODS
  Colombia, August 2015 to July 2017.
  
  
  METHODS
  Population of Colombia, stratified by sex, age, and pregnancy status.
  
  
  METHODS
  Recommendations to delay pregnancy by 3, 6, 9, 12, or 24 months, at different levels of adherence.
  
  
  METHODS
  Weekly and cumulative incidence of prenatal infections and microcephaly cases.
  
  
  RESULTS
  With 50% adherence to recommendations to delay pregnancy by 9 to 24 months, the cumulative incidence of prenatal Zika virus infections is likely to decrease by 17% to 44%, whereas recommendations to delay pregnancy by 6 or fewer months are likely to increase prenatal infections by 2% to 7%. This paradoxical exacerbation of prenatal Zika virus exposure is due to an elevated risk for pregnancies to shift toward the peak of the outbreak.
  
  
  CONCLUSIONS
  Sexual transmission was not explicitly accounted for in the model because of limited data but was implicitly subsumed within the overall transmission rate, which was calibrated to observed incidence.
  
  
  CONCLUSIONS
  Pregnancy delays can have a substantial effect on reducing cases of microcephaly but risks exacerbating the Zika virus outbreak if the duration is not sufficient. Duration of the delay, population adherence, and the timing of initiation of the intervention must be carefully considered.
  
  
  BACKGROUND
  National Institutes of Health.
authors.affiliation: From Yale School of Public Health and Yale University, New Haven, Connecticut.
authors.forename: Martial L
authors.initials: ML
authors.lastname: Ndeffo-Mbah
authors.affiliation: From Yale School of Public Health and Yale University, New Haven, Connecticut.
authors.forename: Alyssa S
authors.initials: AS
authors.lastname: Parpia
authors.affiliation: From Yale School of Public Health and Yale University, New Haven, Connecticut.
authors.forename: Alison P
authors.initials: AP
authors.lastname: Galvani
mesh_terms: D001499:Bayes Theorem; D003105:Colombia / Q000453:epidemiology; D000013:Congenital Abnormalities / Q000517:prevention & control; D005260:Female; D005313:Fetal Death / Q000517:prevention & control; D006291:Health Policy; D006801:Humans; D015994:Incidence; D008297:Male; D008831:Microcephaly / Q000517:prevention & control; D015233:Models, Statistical; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000821:virology; D015995:Prevalence; D015229:Sexually Transmitted Diseases, Viral / Q000453:epidemiology; D013997:Time Factors; D000071243:Zika Virus Infection / Q000150:complications / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission