Impact of vaccination and the omicron variant on COVID-19 severity in pregnant women

We compared the clinical course of pregnant women with coronavirus disease 2019 (COVID-19) before and after the emergence of the omicron variant and based on vaccination status. We retrospectively reviewed the electronic medical charts of 224 patients and 82 deliveries from November 1, 2020, to March 7, 2022; of these, 42% were diagnosed during the omicron dominance period. Disease severity and morbidity of COVID-19 were significantly decreased during the omicron era. The vaccination rates among the patients were higher after omicron emergence (31.9%) than before (6.9%). Overall, 4.1% and 25% of patients had severe symptoms, and 2.6% and 16.2% required oxygen therapy in the vaccination and non-vaccination groups, respectively. Overall, patients had a more favorable clinical course in the omicron era; moreover, vaccinated patients were better protected than non-vaccinated patients, indicating the importance of vaccination against COVID-19.