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Table 3 Summary of studies reporting incidence of symptomatic influenza virus infection

From: Incidence of influenza virus infection among pregnant women: a systematic review

Study Number of cases Denominator Crude incidence rate (CI) 95% CI Pandemic or seasonal? Study design Grading system and scoreb Hospital-based or clinic-based? Duration of surveillance (months or years) Country
Doyle 2013 194 295,941 6.6 per 10,000 pregnanciesa (5.70–7.55) Pandemic Case series NOS = 8 Both 13 months US
Jamieson 2009 34 3,392,060 0.10 per 10,000 pregnancies (0.07–0.14) Pandemic Case series JBI = 6/7 Both 1 month US
Madhi 2014 HIV uninfected:
38
1,023 371 per 10,000 pregnanciesa (272–507) Seasonal Clinical trial Low Risk (Cochrane) Clinic 2 years (9 months total influenza season) South Africa
HIV infected:
16
88 1,818 per 10,000 pregnanciesa (1,167–2,832)       
Total:
54
1,111 486 per 10,000 pregnanciesa (375–630)       
  1. aCalculated from provided number of cases or %
  2. b NOS Newcastle-Ottawa Scale, JBI JBI Critical Appraisal Checklist for Descriptive/Case Series, Cochrane The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials