A brief introduction of the active surveillance for respiratory illness associated with influenza among pregnant women in Suzhou, China

Objective To investigate the incidence rate and assess the disease burden of respiratory illness associated with influenza among pregnant women in Suzhou, China. Methods As a subproject of "The Sino-US Emerging and Re-emerging Infectious Diseases Program",pregnant women were recruited into the cohort since October, 2015 and follow-ups were carried out.Throat swab for influenza was taken for laboratory test when the pregnant women got influenza-like symptoms. Results In total 4438 pregnant women recruit up to 24th July 2016, among which 1 539 are early-pregnancy, middle-pregnancy accounted 2 174 and late-pregnancy took 726.Lost to follow-up rate was 5.5%. And 995 cases of throat swabs was taken and tested (80.83%), of which 68 cases were positive (6.8%). The incidence density was 0.08 per hundred person-weeks. Conclusion This prospective cohort study took laboratory test of influenza virus to investigate the incidence rate of respiratory illness associated with influenza among pregnant women can provide credible data about the incidence of influenza. To a certain extent, this study makes up the blank of such research.