Study population:
A prospective study was conducted at Koc University Hospital between August 2020 and August 2021. Pregnant women with active or recently infected within one month with SARS-CoV-2 were included in the study. SARS-CoV-2 infection was confirmed by a positive nasopharyngeal polymerase chain reaction (PCR) test. The signs and symptoms of COVID-19 were evaluated in all women who had positive PCR tests for SARS-CoV-2 infection. COVID-19 was classified according to NIH COVID-19 clinical guidelines 12. Patients with symptoms including fever, myalgia, or gastrointestinal system symptoms were categorized as a mild disease, those who required oxygen (O2) supplementation as moderate or severe disease (MSD). Recovery was defined as clinical improvement in combination with a negative nasopharyngeal PCR test. Single vaginal swab was collected from each participant at the time of COVID-19 and within one month after recovery from COVID-19. In three patients, longitudinal microbiota analysis was performed with a collection of vaginal swabs before, during active infection, and two months after recovery. The overview of patients was presented in Figure 1.
The healthy controls (HC) were recruited from the prospective study entitled “Vaginal, Placental and Neonatal Buccal Mycobiota, and Microbiome in Preterm Birth”. The study was initiated in April 2020 (ClinicalTrials.gov Identifier: NCT04165252). Maternal age and gestational week-matched pregnant women were selected for the healthy controls. Inclusion criteria for the healthy controls are as follows: age older than 18 years with a singleton pregnancy. The exclusion criteria were multiple pregnancies, major fetal structural defects and/or chromosomal abnormalities, stillbirth, having used antibiotics and/or antifungal medication within two weeks at the time of sample collection, the presence of vaginal bleeding at the time of sample collection, and sexual intercourse within 72 hours of sample collection.
Maternal characteristics, medical and obstetrical history were recorded for all participants. Maternal height and weight were measured at the same time with vaginal swabs collection. Gestational age was determined from the last menstrual period and confirmed from the measurement of fetal crown-rump length at the first-trimester scan. The written informed consent was obtained from all participants. Koç University Research Ethics Board approved the study protocol. The study complies with the decleration of Helsinki.