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Introduction: We evaluated knowledge, attitudes, and practices (KAP) related to influenza and influenza vaccination among pregnant women in three selected countries. Methods: During 2017, pregnant women seeking antenatal care at hospitals at participating sites were enrolled. We described characteristics and responses to KAP questions. We also evaluated predictors associated with influenza vaccination during pregnancy at sites with substantial influenza vaccine uptake by multivariable logistic regression. Results: Overall, 4,648 pregnant women completed the survey. There were substantial differences among the three survey populations; only 8% of the women in Nagpur had heard of influenza, compared to 90% in Lima and 96% in Bangkok (p-value

Background We assessed performance of participant-collected midturbinate nasal swabs compared to study staff-collected midturbinate nasal swabs for the detection of respiratory viruses among pregnant women in Bangkok, Thailand. Methods We enrolled pregnant women aged ≥18 years and followed them throughout the 2018 influenza season. Women with acute respiratory illness self-collected midturbinate nasal swabs at home for influenza viruses, respiratory syncytial viruses (RSV), and human metapneumoviruses (hMPV) real-time RT-PCR testing and the study nurse collected a second midturbinate nasal swab during home visits. Paired specimens were processed and tested on the same day. Results The majority (109, 60%) of 182 participants were 20–30 years old. All 200 paired swabs had optimal specimen quality. The median time from symptom onsets to participant-collected swabs was 2 days and to staff-collected swabs was also 2 days. The median time interval between the 2 swabs was 2 hours. Compared to staff-collected swabs, the participant-collected swabs were 93% sensitive and 99% specific for influenza virus detection, 94% sensitive and 99% specific for RSV detection, and 100% sensitive and 100% specific for hMPV detection. Conclusions Participant-collected midturbinate nasal swabs were a valid alternative approach for laboratory confirmation of influenza-, RSV-, and hMPV-associated illnesses among pregnant women in a community setting.

Background The World Health Organization (WHO) recommends case definitions for influenza surveillance that are also used in public health research, although their performance has not been assessed in many risk groups, including pregnant women in whom influenza may manifest differently. We evaluated the performance of symptom-based definitions to detect influenza in a cohort of pregnant women in India, Peru, and Thailand. Methods In 2017 and 2018, we contacted 11 277 pregnant women twice weekly during the influenza season to identify illnesses with new or worsened cough, runny nose, sore throat, difficulty breathing, or myalgia and collected data on other symptoms and nasal swabs for influenza real-time reverse transcription–polymerase chain reaction (rRT-PCR) testing. We calculated sensitivity, specificity, positive-predictive value, and negative-predictive value of each symptom predictor, WHO respiratory illness case definitions, and a de novo definition derived from results of multivariable modeling. Results Of 5444 eligible illness episodes among 3965 participants, 310 (6%) were positive for influenza. In a multivariable model, measured fever ≥38°C (adjusted odds ratio [95% confidence interval], 4.6 [3.1–6.8]), myalgia (3.0 [2.2–4.0]), cough (2.7 [1.9–3.9]), and chills (1.6 [1.1–2.4]) were independently associated with influenza illness. A definition based on these 4 (measured fever, cough, chills, or myalgia) was 95% sensitive and 27% specific. The WHO influenza-like illness (ILI) definition was 16% sensitive and 98% specific. Conclusions The current WHO ILI case definition was highly specific but had low sensitivity. The intended use of case definitions should be considered when evaluating the tradeoff between sensitivity and specificity.

Background The World Health Organization (WHO) recommends case definitions for influenza surveillance that are also used in public health research, though their performance has not been assessed in many risk groups, including pregnant women in whom influenza may manifest differently. Â We evaluated the performance of symptom-based case definitions to detect influenza in a cohort of pregnant women in India, Peru, and Thailand. Methods In 2017, we contacted 4774 pregnant women twice a week during the influenza season to identify illnesses with new or worsened cough, runny nose, sore throat, difficulty breathing or myalgia, and collected data on other symptoms and nasal swabs for influenza rRT–PCR testing. To identify symptom predictors of influenza, we used multivariable logistic regression with forward selection of symptoms significant in univariate analysis after controlling for country, chronic conditions, influenza vaccination, and time from symptom onset to swab collection. We calculated sensitivity and specificity of each symptom, WHO respiratory illness case definitions and a case definition based on significant predictors from the multivariable model. Results Of 2431 eligible illness episodes among 1,716 participants, 142 (5.8%) were positive for influenza. Among individual symptoms, runny nose was most sensitive and measured fever ≥ 38° Celsius was most specific (Figure 1). In a multivariable model, measured fever ≥ 38° Celsius [adjusted odds ratio = 3.8, 95% confidence interval [CI] = 2.0–7.2], cough [2.7, CI 1.6–4.7], chills [2.2, CI 1.2–3.8], and myalgia [1.2, CI 2.2, 5.3] were independently associated with influenza illness. A case definition based on these four (measured fever, cough, chills or myalgia), was 91%-sensitive and 37% specific. Sensitivity and specificity of case definitions varied (Figure 2). Conclusion While a case definition based on one or more of fever, chills, cough or myalgia is highly-sensitive and moderately specific among pregnant women, case definitions requiring measured or subjective fever may miss many influenza cases making them sub-optimal for studies of burden or vaccine efficacy. The intended use of case definitions should be considered when evaluating the tradeoff between sensitivity and specificity. Disclosures All authors: No reported disclosures.

Background The World Health Organization recommends influenza vaccination for pregnant women. However, few data exist on influenza incidence and clinical course among pregnant women in middle-income countries where influenza vaccine use during pregnancy is often limited. We conducted a prospective cohort study of pregnant women to estimate incidences of influenza in Lima, Peru; Bangkok, Thailand; and Nagpur, India. Methods Prior to and early in the 2017 and 2018 influenza seasons, we enrolled pregnant women aged > 18 years with expected delivery dates > 8 weeks after the start of the season. We contacted women twice weekly until end of pregnancy to identify illnesses with myalgia, cough, runny nose, sore throat, or difficulty breathing and collected nasal swabs from symptomatic women for influenza real-time reverse transcription polymerase chain reaction testing. Using 2017 cohort data, we calculated crude incidences per 10,000 pregnancy-months during influenza season by site and trimester and overall incidence weighted for population of women of childbearing age in each country. Results We enrolled 4774 women with a median age of 26 years (interquartile range [IQR] 23–31) and gestational age of 20 weeks (IQR 15–24); 15% received influenza vaccine. Local influenza seasons spanned 4.5–8 months. Overall, 143 participants (3%) had influenza (113 (79%) influenza A and 30 (21%) influenza B). Weighted influenza incidence was 88.7/10,000 pregnancy-months (95% CI 68.6–114.8), though incidences varied up to two-fold by site (Figure 1). Incidences did not differ by pregnancy trimester (Figure 2). Among the 143 influenza episodes, the median duration was 7 days (IQR 5–10), 30% involved fever or chills, 43% disrupted daily activities, 47% prompted medical attention, 4% were associated with hospitalization, and < 1% were treated with antiviral medications. Conclusion Overall, pregnant women had an average risk of influenza of 0.9% per month of pregnancy spent in the influenza season with almost half of illnesses disrupting daily activities and prompting medical attention. Influenza-associated hospitalization was infrequent. These findings provide valuable inputs to estimate illnesses averted by vaccine programs and evaluate their cost–benefit among pregnant women in middle-income countries. Disclosures All authors: No reported disclosures.