Table 3.
Summary of studies reporting incidence of symptomatic influenza virus infection
| 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) |
aCalculated from provided number of cases or %
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