biostudies-literatureUnknown401(10375)Villar J<h4>Background</h4>In 2021, we showed an increased risk associated with COVID-19 in pregnancy. Since then, the SARS-CoV-2 virus has undergone genetic mutations. We aimed to examine the effects on maternal and perinatal outcomes of COVID-19 during pregnancy, and evaluate vaccine effectiveness, when omicron (B.1.1.529) was the variant of concern.<h4>Methods</h4>INTERCOVID-2022 is a large, prospective, observational study, involving 41 hospitals across 18 countries. Each woman with real-time PCR or rapid test, laboratory-confirmed COVID-19 in pregnancy was compared with two unmatched women without a COVID-19 diagnosis who were recruited concomitantly and consecutively in pregnancy or at delivery. Mother and neonate dyads were followed until hospital discharge. Primary outcomes were maternal mLancet (London, England)447-457https://www.ebi.ac.uk/biostudies/studies/S-EPMC9910845biostudies-literaturePregnancy outcomes and vaccine effectiveness during the period of omicron as the variant of concern, INTERCOVID-2022: a multinational, observational study.PMC9910845Tavchioska GSavasi VPapageorghiou ATErnawati EBhutta ZANapolitano RFabre MGunier RBSalomon LJMarler EWinsey AHubka TCasale RAPeterson AEskenazi BINTERCOVID-2022 International ConsortiumTeji JSDeantoni SCaceres DMGandino SRauch SCavoretto PILipschuetz MVecchiarelli CAyede AIMaiz NRodriguez GBThornton JGTug NDeruelle PCapelli CSoto Conti CPBako BNieto RGravett MGVillar JEaster SRCraik RGiudice CIkenoue SMenis CTakahashi KAriff SHernandez VLivio SPrefumo FKennedy SHSentilhes LAlbornoz Crespo GRodriguez-Sibaja MJVale MMartinez de Tejada BSobrero HCheikh Ismail LfalsePregnancy outcomes and vaccine effectiveness during the period of omicron as the variant of concern, INTERCOVID-2022: a multinational, observational study.<h4>Background</h4>In 2021, we showed an increased risk associated with COVID-19 in pregnancy. Since then, the SARS-CoV-2 virus has undergone genetic mutations. We aimed to examine the effects on maternal and perinatal outcomes of COVID-19 during pregnancy, and evaluate vaccine effectiveness, when omicron (B.1.1.529) was the variant of concern.<h4>Methods</h4>INTERCOVID-2022 is a large, prospective, observational study, involving 41 hospitals across 18 countries. Each woman with real-time PCR or rapid test, laboratory-confirmed COVID-19 in pregnancy was compared with two unmatched women without a COVID-19 diagnosis who were recruited concomitantly and consecutively in pregnancy or at delivery. Mother and neonate dyads were followed until hospital discharge. Primary outcomes were maternal m2023-01-01T00:00:00Z2023 Feb2026-03-16T08:12:18.148Z2024-11-08T14:00:23.443ZS-EPMC99108453666952010.1016/S0140-6736(22)02467-9