Table 1 Summary of studies identified in systematic literature review of Incidence of influenza virus infection among pregnant women
From: Incidence of influenza virus infection among pregnant women: a systematic review
Study | Outcome assesseda | Pandemic or seasonal | Study Design | Methodology | Denominator calculation | Dates of surveillance | Lab Test | Country (WHO Region) b | Country Income Level |
|---|---|---|---|---|---|---|---|---|---|
Creanga 2010 | HA, ICU, D | Pandemic | Case series | Retrospective chart review: pregnant women hospitalized with confirmed H1N1 identified through “enhanced surveillance.” Testing performance only when requested by hospital. | Estimation using 2007 vital registration data (similar approach as in Jamieson et al.) | 05/01/2009–06/30/2009 | RT-PCR | US (PAHO) | High |
Doyle 2013 | SI, HA, ICU, D | Pandemic | Case series | Cases of pH1N1-confirmed acute respiratory illness reported by health providers to state of Florida | Florida birth registry data | 04/24/2009–05/31/2010 | RT-PCR or viral culture | US (PAHO) | High |
Griffiths 1980 | I | Seasonal | Cohort | Serological testing of women “booked” for antenatal care at one hospital in England during three years. Only women with postpartum specimens available were included. | Number of study participants | 05/1975–11/1975; 12/1975–06/1976; 08/1976–04/1977 | HI serology with 4-fold rise in antibody titer | UK (EURO) | High |
Hardy 1961 | I | Pandemic | Cohort | All pregnant women treated at Johns Hopkins Obstetrical Prenatal Clinic, with blood samples taken and questionnaires about symptoms administered monthly through delivery. Anyone with high HI titer was considered a case. | Number of study participants | 10/14/1957–02/01/1958 | Complement Complement fixation or HI test; no increase in titers required to be considered a case | US (PAHO) | High |
Irving 2000 | I | Seasonal | Cohort | Women delivering at two hospitals in Nottingham, England with available antenatal and postnatal sera. | Number of study participants | 05/1993–07/1994 | Single radial hemolysis and paired specimens for HI titer | UK (EURO) | High |
Jamieson 2009 | SI, HA, ICU, D | Pandemic | Case series | Pregnant women with confirmed or probable H1 infection reported by states to CDC as part of “enhanced” surveillance. | US Census bureau data | 04/15/2009–05/18/2009 | Confirmed: RT-PCR or viral culture+for H1. Probable: RT-PCR flu A+ but (−) for known subtypes | US (PAHO) | High |
Knight 2011 | ICU, D | Pandemic | Case series | Cases of H1 lab-confirmed ICU admission among pregnant women in Australia and New Zealand reported to Australian and New Zealand Intensive Care (ANZIC) study. Cases in UK reported to UK Obstetric Surveillance System. | National statistics on pregnancies combined with total birth data | AUS/NZ: 06/01/2009–08/31/2009 UK: 09/01/2009–01/31/2010 | Not stated in manuscript (but referenced) | Australia and New Zealand (WPRO) UK (EURO) | High |
Madhi 2014 | SI | Seasonal | Randomized Clinical trial | RCT of influenza vaccine efficacy. All participants with ILI or unknown respiratory illness were tested for influenza. | All women enrolled in placebo arm of study | 03/2011–08/2011; 03/2012–07/2012 | RT-PCR | South Africa (AFRO) | Upper-Middle |
Yates 2010c | HA, ICU, D | Pandemic | Case series | Clinician-reported of H1-confirmed pregnant women admitted to 221/223 hospitals with consultant-led maternity units in the UK. Surveillance included zero-reporting and follow-up of reported cases. | Birth data from UK office for national statistics | 09/01/2009–01/31/2010 | Not specified | UK (EURO) | High |