COMMENT & RESPONSEIn Reply We appreciate the letter from Triunfo and Boselli and applaud their efforts to promote COVID-19 vaccination in pregnant people in Italy. We agree with Triunfo and Boselli that our study 1 from the Vaccine Safety Datalink showing no association between first trimester vaccination and major structural birth defects among 42 156 live births, including 7632 with first trimester mRNA COVID-19 vaccination, is reassuring. Our results are consistent with a recent publication from Magnus and colleagues, 2 which found vaccination was not associated with congenital anomalies among 152 261 live births in Norway, Sweden, and Denmark, including 29 135 with first trimester mRNA COVID-19 vaccine exposures. While accumulating evidence supports the safety of first trimester COVID-19 vaccination, we disagree with Triunfo and Boselli that our study "encourages vaccination against COVID-19 in early pregnancy." Additional data on the benefits of vaccination by trimester or gestational week, considering a range of maternal and infant outcomes, would be needed to specifically endorse COVID-19 vaccination in early pregnancy vs administration later in pregnancy.Prior observational studies have noted that risks for adverse birth outcomes, such as preterm birth, are increased with third trimester SARS-CoV-2 infections, compared to infections earlier in pregnancy. 3 In addition, similar to nonpregnant populations, benefits of vaccination or protection from severe infections likely wanes over time. Thus, it is possible that vaccination in early pregnancy could leave pregnant people vulnerable to SARS-CoV-2 infection late in pregnancy. Furthermore, approaches to COVID-19 vaccination in pregnancy that optimize transplacental immunoglobulin transfer and potentially increase infant protection may differ from approaches aiming to optimize maternal health and prevent severe maternal morbidity.The US Centers for Disease Control and Prevention recommends everyone 6 months or older should be vaccinated with the updated 2024-2025 COVID-19 vaccine. This guidance applies to pregnant people without regard to trimester. 4 Similarly, the World Health Organization recommends COVID-19 vaccination in any trimester of pregnancy. 5 Encouraging vaccination throughout pregnancy, without a preference for timing, has many advantages. Pregnant people may also be eligible for influenza; diphtheria, tetanus, and acellular pertussis; and respiratory syncytial virus vaccines during pregnancy. Recommendations to administer the COVID-19 vaccine at any time during pregnancy can limit the need to administer multiple vaccines on a single day. Furthermore, recommendations to vaccinate in any trimester can offer pregnant people more opportunities to be vaccinated and the autonomy to decide when to receive this safe and effective vaccine.
