key: cord-0742698-9nhyulp6 authors: Sookaromdee, Pathum; Wiwanitkit, Viroj title: Contraception, vaccination and coronavirus disease 2019 pandemic: correspondence date: 2022-03-18 journal: Obstet Gynecol Sci DOI: 10.5468/ogs.22045 sha: 5cf099c4944ef3c5045b504336310e9d2e66f345 doc_id: 742698 cord_uid: 9nhyulp6 nan Dear Editor, we would like to discuss the publication entitled "Contraception in the coronavirus disease 2019 (COVID-19) pandemic: recommendations from the Korean society of contraception and reproductive health" [1] . Lee et al. [1] mentioned that "rare form of thrombosis has been reported in people who received the COVID-19 vaccine, most of whom were women younger than 50 years of age… of guidelines for the use of hormonal contraceptives in the era of the CO-VID-19 pandemic is necessary". We agree that the COVID-19 vaccine can have adverse effects. The question regarding risks related to contraception is an interesting one. We agree that the usefulness and benefit of vaccination are superior to the risk. Regarding thrombosis in a COVID-19 vaccine recipient who uses contraception, there might be some previous reports. However, it should be noted that most studies lack data on the pre-vaccination status of the patient. Patients with a history of contraceptive drug use might have underlying diseases that can lead to thrombosis. It should also be noted that not all thromboses that occur after vaccination are caused by vaccination. The patient might have other medical problems leading to thrombosis [2] . Considering the pathogenesis of thrombosis, an important mechanism is increased blood viscosity [3] . Focusing on contraceptive drug use, increased blood viscosity might be observed [4] . However, the increased level is not high and does not increase the risk of vaccine-related thrombosis. The problem should be a concern only if there is an additional medical illness, such as metabolic syndrome and cardiac problems, in vaccinated women. Therefore, we should reassure the safety of CO-VID-19 vaccination for any woman with concomitant use of contraceptive drug. Contraception in the COVID-19 pandemic: recommendations from the Korean society of contraception and reproductive health Thrombosis after adenovirus-vectored COVID-19 vaccination: a concern on underlying illness Expected viscosity after COVID-19 vaccination, hyperviscosity and previous COVID-19 Increased blood viscosity in young women using oral contraceptives Vol. 65, No. 3, 2022