Feasibility and Performance of Self-Collected Nasal Swabs for Detection of Influenza Virus, Respiratory Syncytial Virus, and Human Metapneumovirus.

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.

What do pregnant women think about influenza disease and vaccination practices in selected countries.

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<0.01). Despite significant differences in sociodemographic characteristics in the three populations, most participants across sites who were aware of influenza prior to study enrollment believe they and their infants are at risk of influenza and related complications and believe influenza vaccination is safe and effective. Half of women in Lima had verified receipt of influenza vaccine compared to <5% in Bangkok and Nagpur (p < .05). For further analysis conducted among women in Lima only, household income above the poverty line (aOR: 1.38; 95%CI: 1.01, 1.88), having 8+ antenatal visits, compared to 0-4 (aOR: 2.41; 95%CI: 1.39, 2.87, respectively), having 0 children, compared to 2+ (aOR: 1.96; 95%CIs: 1.23, 3.12), and vaccination recommended by a health-care provider (aOR: 8.25; 95%CI: 6.11, 11.14) were strongly associated with receipt of influenza vaccine during pregnancy.Conclusions: Our findings identify opportunities for targeted interventions to improve influenza vaccine uptake among pregnant women in these settings.

Performance of Symptom-Based Case Definitions to Identify Influenza Virus Infection Among Pregnant Women in Middle-Income Countries: Findings From the Pregnancy and Influenza Multinational Epidemiologic (PRIME) Study.

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.

The Pregnancy and Influenza Multinational Epidemiologic (PRIME) study: a prospective cohort study of the impact of influenza during pregnancy among women in middle-income countries.

BACKGROUND: The World Health Organization identifies pregnant women as at high-risk for severe influenza, but influenza vaccines are underutilized among pregnant women. Data on influenza burden during pregnancy are largely limited to high-income countries and data on the impact of influenza on birth and perinatal outcomes are scarce. METHODS/DESIGN: This prospective, longitudinal cohort study of pregnant women in middle-income countries is designed to address three primary objectives: 1) to evaluate the effect of laboratory-confirmed influenza during pregnancy on pregnancy and perinatal outcomes; 2) to estimate the incidences of all-cause acute respiratory illness and laboratory-confirmed influenza during pregnancy; and 3) to examine the clinical spectrum of illness associated with influenza viruses. Through a multi-country network approach, three sites aim to enroll cohorts of 1500-3000 pregnant women just before local influenza seasons. Women aged ≥ 18 years with expected delivery dates ≥ 8 weeks after the start of the influenza season are eligible. Women are followed throughout pregnancy through twice weekly surveillance for influenza symptoms (≥ 1 of myalgia, cough, runny nose, sore throat, or difficulty breathing) and have mid-turbinate nasal swabs collected for influenza virus testing during illness episodes. Primary outcomes include relative risk of preterm birth and mean birth weight among term singleton infants of women with and without reverse transcription polymerase chain reaction-confirmed influenza during pregnancy. Gestational age is determined by ultrasound at < 28 weeks gestation and birth weight is measured by digital scales using standardized methods. Sites are primarily urban in Bangkok, Thailand; Lima, Peru; and Nagpur, India. All sites recruit from antenatal clinics at referral hospitals and conduct surveillance using telephone calls, messaging applications, or home visits. Nasal swabs are self-collected by participants in Thailand and by study staff in Peru and India. During the first year (2017), sites enrolled participants during March-May in Peru and May-July in India and Thailand; 4779 women were enrolled. DISCUSSION: This study aims to generate evidence of the impact of influenza during pregnancy to inform decisions by Ministries of Health, healthcare providers, and pregnant women in middle-income countries about the value of influenza vaccination during pregnancy.