South Korean study shows COVID-19 vaccination safe and effective in early pregnancy

COVID-19 vaccination is safe and effective before and during early pregnancy, according to a recent study published in the Journal of Korean Medical Science.

Although clinical data has indicated reduced morbidity risk and a favorable safety profile from the COVID-19 vaccine in pregnant women, many women still express vaccine hesitancy when planning pregnancy. This is especially based on concern of miscarriage and congenital anomalies in their babies.

COVID-19 vaccination among pregnant women is low in South Korea, indicating a need to investigate the safety and efficacy of the vaccine in this population. Investigators conducted a study to determine the association between maternal COVID-19 vaccination preconception and miscarriage or severe maternal SARS-CoV-2 infection.

Vaccine hesitation prevents pregnant women from receiving vaccinations to protect themselves against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Prior studies on the safety and efficacy of COVID-19 vaccination in this population have methodological limitations, and data from Asian countries is lacking.

The investigators obtained data from the Korean Disease Control and Prevention Agency-COVID-19-National Health Insurance Service cohort. This included SARS-CoV-2 infection cases from October 2020 to December 2021.

Participants were aged 20 to 44 years and had a valid pregnancy confirmed by pregnancy and treatment codes for first-trimester obstetric ultrasonography (T1US) between February 1, 2021, and December 31, 2021. Only women without documented SARS-CoV-2 infection within the 20th gestational week were included.

Exclusion criteria included last menstrual period (LMP) between August 2021 and December 2021 and a history of COVID-19 infection during the preconceptional and preclinical periods. There were 2 groups of patients, the first of which was a preconceptional vaccination group and the second a preclinical vaccination group.

The preconceptional vaccination group was first vaccinated within 6 months before LMP, while the preclinical vaccination group was first vaccinated between LMP and T1US. The risk of SARS-CoV-2 infection was determined based on intensive care unit (ICU) admission. COVID-19 infection was identified using polymerase chain reaction (PCR).

The safety of the COVID-19 vaccine in the preconception and preclinical groups was determined based on early abortive pregnancy outcomes such as ectopic pregnancy, miscarriage, artificial abortion, and molar pregnancy. Covariates included body mass index, age at vaccination, season of conception, and socioeconomic status.

A COVID-19 vaccination rate of 3.1% was reported in the preconceptional pregnancy period vs 2.6% of the preclinical pregnancy period. When compared to matching controls, increased survivability and employment rates in the Seoul capital area was observed in patients vaccinated during the preconceptional or preclinical pregnancy periods.

Early abortive outcomes were reported in 20.7% of unvaccinated women and 21.6% of women vaccinated during the preconceptional period. Significant differences in early abortive outcomes were not observed between both groups. Similar results were seen when comparing unvaccinated women to those vaccinated during the preclinical period.

These results indicated comparable risks of early abortive outcomes between individuals unvaccinated and vaccinated against COVID-19, as well as improved rates of COVID-19 infection in vaccinated individuals. Investigators recommended future studies evaluate the long-term safety and efficacy of COVID-19 vaccination for pregnant women and their offspring.

Reference

Gwak E, Kim T, Shin JY, et al.Effectiveness and safety of COVID-19 vaccination during preconceptional and preclinical pregnancy period: A national population study. J Korean Med Sci. 2023;38(41):e314. doi:10.3346/jkms.2023.38.e314