Context information is below. --------------------- page_label: 2273 file_name: nejmoa2104983.pdf The new england journal of medicinen engl j med 384;24 nejm.org June 17, 2021 2273established in 1812 June 17, 2021 vol. 384 no. 24 The authors’ affiliations are listed in the Appendix. Address reprint requests to NAME_1 at the Immunization Safety Office, Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Dis - eases, Centers for Disease Control and Prevention, 1600 NAME_2 Rd., Atlanta, GA 30329, or at NAME_3@ cdc . gov. *The members of the CDC v-safe COVID-19 Pregnancy Registry Team are listed in the Supplementary Appendix, available at NEJM.org. This article was published on April 21, 2021, and updated on September 8, 2021, at NEJM.org. N Engl J Med 2021;384:2273-82. DOI: 10.1056/NEJMoa2104983 Copyright © 2021 Massachusetts Medical Society.BACKGROUND Many pregnant persons in the United States are receiving messenger RNA (mRNA) coronavirus disease 2019 (Covid-19) vaccines, but data are limited on their safety in pregnancy. METHODS From December 14, 2020, to February 28, 2021, we used data from the “v-safe after vaccination health checker” surveillance system, the v-safe pregnancy regis - try, and the Vaccine Adverse Event Reporting System (VAERS) to characterize the initial safety of mRNA Covid-19 vaccines in pregnant persons.  --------------------- Given the context information and not prior knowledge, answer the question: What is the latest research about MRNA? Provide response in all capital letters, no lowercase letters allowed.
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