Wanitchaya Kittikraisak’s research while affiliated with Centers for Disease Control and Prevention and other places

Background We estimated RSV and hMPV illness incidences among pregnant women and examined the association between antenatal RSV illness and preterm birth and small for gestational age (SGA). Methods Pregnant women aged ≥18 years were followed twice weekly until the end of pregnancy to identify illness episodes with >1 of myalgia, cough, runny nose/nasal congestion, sore throat, or difficulty breathing. Mid-turbinate nasal swabs were collected and tested for RSV and hMPV by real-time reverse-transcription PCR. Incidences were calculated. Cox proportional hazards regression was used to estimate hazard ratios (HRs) comparing participants with and without RSV illnesses for preterm birth (live birth before 37 weeks gestation) and SGA infant. Results Among 2,764 participants, the median age was 29 years (interquartile range [IQR] 24-34) and the median enrollment gestational age was 10 weeks (IQR 7-14). Overall, 71 (3%) and 29 (1%) cases of RSV and hMPV illnesses were identified, respectively. Among these, 30 (42%) and 10 (34%), respectively, sought medical care. Incidence rates per 10,000 pregnant woman-months were 57 (95% confidence interval [CI] 44-72) for RSV and 23 (95% CI 16-33) for hMPV illnesses. Antenatal RSV illness in the third trimester conferred an increased risk of preterm birth (adjusted HR [aHR] 2.50, 95% CI 1.04-6.00) but not having an SGA infant (aHR 0.79, 95% CI 0.29 to 2.16). Conclusions Antenatal RSV illness was associated with some adverse antenatal outcomes. Pregnant women had a 0.4-0.7% risk of RSV illness per pregnancy month, of which one third resulted in medical visits.

Background Seasonal influenza illness and acute respiratory infections can impose a substantial economic burden in low‐ and middle‐income countries (LMICs). We assessed the cost of influenza illness and acute respiratory infections across household income strata. Methods We conducted a secondary analysis of data from a prior systematic review of costs of influenza and other respiratory illnesses in LMICs and contacted authors to obtain data on cost of illness (COI) for laboratory‐confirmed influenza‐like illness and acute respiratory infection. We calculated the COI by household income strata and calculated the out‐of‐pocket (OOP) cost as a proportion of household income. Results We included 11 studies representing 11 LMICs. OOP expenses, as a proportion of annual household income, were highest among the lowest income quintile in 10 of 11 studies: in 4/4 studies among the general population, in 6/7 studies among children, 2/2 studies among older adults, and in the sole study for adults with chronic medical conditions. COI was generally higher for hospitalizations compared with outpatient illnesses; median OOP costs for hospitalizations exceeded 10% of annual household income among the general population and children in Kenya, as well as for older adults and adults with chronic medical conditions in China. Conclusions The findings indicate that influenza and acute respiratory infections pose a considerable economic burden, particularly from hospitalizations, on the lowest income households in LMICs. Future evaluations could investigate specific drivers of COI in low‐income household and identify interventions that may address these, including exploring household coping mechanisms. Cost‐effectiveness analyses could incorporate health inequity analyses, in pursuit of health equity.

Background We examined the added value of serologic testing for estimating influenza virus infection incidence based on illness surveillance with molecular testing versus periodic serologic testing. Methods Pregnant persons unvaccinated against influenza at <28 weeks gestation were enrolled before the 2017 and 2018 influenza seasons in Peru and Thailand. Blood specimens were collected at enrollment and ≤14 days postpartum for testing by hemagglutination inhibition assay for antibodies against influenza reference viruses. Seroconversion was defined as a ≥4-fold rise in antibody titers from enrollment to postpartum with the second specimen’s titer of ≥40. Throughout pregnancy, participants responded to twice weekly surveillance contacts asking about influenza vaccination and influenza-like symptoms (ILS). A mid-turbinate swab was collected with each ILS episode for influenza real-time reverse transcription polymerase chain reaction (rRT-PCR). Results Of 1,466 participants without evidence of influenza vaccination during pregnancy, 296 (20.2%) had evidence of influenza virus infections. Fifteen (5.1%) were detected by rRT-PCR only, 250 (84.4%) by serologic testing only, and 31 (10.5%) by both methods. Conclusions Influenza virus infections during pregnancy occurred in 20% of cohort participants; >80% were not detected by a broad illness case definition coupled with rRT-PCR.

Background Cesarean delivery rates have increased globally resulting in a public health concern. We estimate rates of cesarean deliveries among Thai women using the World Health Organization (WHO) Robson Classification system and compare rates by Robson group to the Robson guideline for acceptable rates to identify groups that might benefit most from interventions for rate reduction. Methods In 2017 and 2018, we established cohorts of pregnant women aged ≥ 18 years seeking prenatal care at two tertiary Thai hospitals and followed them until 6–8 weeks postpartum. Three in-person interviews (enrollment, end of pregnancy, and postpartum) were conducted using structured questionnaires to obtain demographic characteristics, health history, and delivery information. Cesarean delivery indication was classified based on core obstetric variables (parity, previous cesarean delivery, number of fetuses, fetal presentation, gestational week, and onset of labor) assigned to 10 groups according to the Robson Classification. Logistic regression was used to identify factors associated with cesarean delivery among nulliparous women with singleton, cephalic, term pregnancies. Results Of 2,137 participants, 970 (45%) had cesarean deliveries. The median maternal age at delivery was 29 years (interquartile range, 25–35); 271 (13%) participants had existing medical conditions; and 446 (21%) had pregnancy complications. The cesarean delivery rate varied by Robson group. Multiparous women with > 1 previous uterine scar, with a single cephalic pregnancy, ≥ 37 weeks gestation (group 5) contributed the most (14%) to the overall cesarean rate, whereas those with a single pregnancy with a transverse or oblique lie, including women with previous uterine scars (group 9) contributed the least (< 1%). Factors independently associated with cesarean delivery included age ≥ 25 years, pre-pregnancy obesity, new/worsen medical condition during pregnancy, fetal distress, abnormal labor, infant size for gestational age ≥ 50 th percentiles, and self-pay for delivery fees. Women with existing blood conditions were less likely to have cesarean delivery. Conclusions Almost one in two pregnancies among women in our cohorts resulted in cesarean deliveries. Compared to WHO guidelines, cesarean delivery rates were elevated in selected Robson groups indicating that tailored interventions to minimize non-clinically indicated cesarean delivery for specific groups of pregnancies may be warranted.

Introduction: With the licensure of maternal RSV vaccines in Europe and USA, data are needed to better characterize the burden of respiratory syncytial virus (RSV)-associated acute respiratory infections (ARI) in pregnancy. This study aims to determine among pregnant individuals the proportion of ARI testing positive for RSV and RSV incidence rate, RSV-associated hospitalizations, deaths, and perinatal outcomes. Methods: We conducted a systematic review following PRISMA 2020 guidelines using five databases (Medline, Embase, Global Health, Web of Science and Global Index Medicus) and included additional unpublished data. Pregnant individuals with respiratory infections who had respiratory samples tested for RSV were included. We used a random-effects meta-analysis to generate overall proportions and rate estimates across studies. Results: Eleven studies with pregnant individuals recruited between 2010 and 2022 were identified, most of which recruited pregnant individuals in community, inpatient and outpatient settings. Among 8126 pregnant individuals, the proportion with respiratory infections that tested positive for RSV ranged from 0.9% to 10.7%, with a meta-estimate of 3.4% (95% CI: 1.9; 54). The pooled incidence rate of RSV infection episodes among pregnant individuals was 26.0 (15.8; 36.2) per 1000 person-years. RSV hospitalization rates reported in two studies were 2.4 and 3.0 per 1000 person-years. Of five studies that ascertained RSV-associated deaths among 4708 pregnant individuals, no deaths were reported. Three studies comparing RSV-positive and RSV-negative pregnant individuals found no difference in odds of miscarriage, stillbirth, low birth weight, and small for gestational age. RSV-positive pregnant individuals had higher odds of preterm delivery (odds ratio 3.6 [1.3; 10.3]). Conclusion: Data on RSV-associated hospitalization incidence rates are limited but available estimates are lower than those reported in older adults and young children. As countries debate whether to include RSV vaccines in maternal vaccination programs, which are primarily intended to protect infants, this information could be useful in shaping vaccine policy decisions.

Objectives: Personal protective equipment (PPE) use is associated with reduced risk of SARS-CoV-2 infection among healthcare personnel (HCP). There are limited data on the impact of the novel coronavirus disease 2019 (COVID-19) pandemic on the PPE use of HCP. We describe the changes in PPE use from just before the widespread of community outbreaks ('pre-pandemic') to intra-pandemic time points, and examine factors associated with not changing in PPE use behavior among HCP in four Thai hospitals. Methods: We performed a retrospective cohort evaluation using two-time points: (i) February-March 2020 (pre-pandemic period); and (ii) January-March 2021 (intra-pandemic period). Self-reported frequency of appropriate PPE use was measured by a Likert scale. We used multivariable logistic regression to identify factors associated with no increase in self-reported PPE use. Results: Of 343 HCP, the proportion of participants reporting 'always' using PPE rose from 66% during the pre-pandemic period to 80% during the pandemic. Factors associated with HCP who did not increase in PPE use included having high baseline reported PPE, being a non-registered HCP (e.g. nurse assistants, dental assistants, porters), being male, and having a low perceived risk of becoming infected with any respiratory virus while working in the hospital. Conclusion: PPE education, training, and risk communication content should target all cadres of HCP, regardless of registered/non-registered status, with a focus on behavior change for improved prevention and control of SARS-CoV-2 and other respiratory viruses in healthcare settings.

Objectives: We estimated influenza-like symptom (ILS) incidence among healthcare personnel (HCP) in four hospitals and the economic impact due to ILS in the Thai HCP population during July 2020-June 2021 (Thailand's expected 2020 influenza season), which also coincided with the novel coronavirus disease 2019 pandemic. Methods: We followed HCP, in a prospective observational cohort, weekly for ≥1 of: muscle pain, cough, runny nose/nasal congestion, sore throat, or difficulty breathing. We fitted population-averaged Poisson regression models to identify factors associated with acquiring ILS and to calculate ILS incidence. We applied epidemiologic parameters to Thailand's HCP population (227 349 persons) to estimate economic impact. Results: Of 2184 participants, adjusted all-cause ILS incidence was 6.1 episodes per 100 person-years (95% confidence interval 3.4-10.9). Among Thailand's HCP population, 13 909 ILS episodes were estimated to occur annually and would result in US$235 135 economic loss. Controlling for study site and calendar month, factors associated with acquiring ≥1 ILS versus no ILS included being female, having asthma, and using personal protective equipment 'frequently, but not always'. Conclusions: All-cause ILS resulted in considerable economic loss among Thai HCP workforce. These findings underscore the importance of public health interventions to reduce the risk of acquiring ILS.

Background: We examined SARS-CoV-2 anti-spike 1 IgG antibody levels following COVID-19 vaccination (AstraZeneca [AZ], Sinovac [SV], Pfizer-BioNTech [PZ]) among Thai healthcare providers. Methods: Blood specimens were tested using enzyme-linked immunosorbent assay. We analyzed seven vaccination regimens: (1) one dose of AZ or SV, (2) two doses of homologous (2AZ, 2SV) or heterologous (1AZ + 1PZ) vaccines, and (3) three doses of heterologous vaccines (2SV + 1AZ, 2SV + 1PZ). Differences in antibody levels were assessed using Kruskal–Wallis statistic, Mann–Whitney test, or Wilcoxon matched pairs signed-rank test. Antibody kinetics were predicted using fractional polynomial regression. Results: The 563 participants had median age of 39 years; 92% were female; 74% reported no underlying medical condition. Antibody levels peaked at 22–23 days in both 1AZ and 2SV vaccinees and dropped below assay’s cutoff for positive (35.2 binding antibody units/ml [BAU/ml]) in 55 days among 1AZ vaccinees compared with 117 days among 2SV vaccinees. 1AZ + 1PZ vaccination regimen was highly immunogenic (median 2279 BAU/ml) 1–4 weeks post vaccination. 2SV + 1PZ vaccinees had significantly higher antibody levels than 2SV + 1AZ vaccinees 4 weeks post vaccination (3423 vs. 2105 BAU/ml; p-value < 0.01), and during weeks 5–8 (3656 vs. 1072 BAU/ml; p-value < 0.01). Antibodies peaked at 12–15 days in both 2SV + 1PZ and 2SV + 1AZ vaccinees, but those of 2SV + 1AZ declined more rapidly and dropped below assay’s cutoff in 228 days while those of 2SV + 1PZ remained detectable. Conclusions: 1AZ + 1PZ, 2SV + 1AZ, and 2SV + 1PZ vaccinees had substantial IgG levels, suggesting that these individuals likely mounted sufficient anti-S1 IgG antibodies for possible protection against SARS-CoV-2 infection.

Background: We examined the characteristics of healthcare providers’ (HCPs) encounters, and the frequency of worker absenteeism/presenteeism, among HCPs in inpatient wards at a tertiary-level public hospital in Bangkok, Thailand. The wards were stratified by risk of respiratory virus transmission: low-risk (Surgery, Rehabilitation, Orthopedic, and Obstetrics and Gynecology) and high-risk (Medicine, Pediatric, Emergency, and Ear, Nose, and Throat) . Methods: Observers followed HCPs throughout one self-selected 8-hour work shift to record their interaction with others. An encounter was defined as a 2-way conversation with ≥3 words in the physical presence of ≥1 person at