evidence: To tease out the effect of vaccination, the researchers compared the impact of COVID-19 infection on preterm births between areas with the fastest vaccine uptake and those with the slowest. Zip codes with the fastest uptake had an 86% vaccination rate by March 2022. Those with the lowest rates reached 51% during the same time period. Until May 2021, the impact of COVID-19 infection on preterm birth rates was similar between areas. They then dropped sharply in high-vaccination areas, while staying high in low-vaccination areas until almost a year later. This strongly suggests that vaccination accounted for the difference in the rate of preterm births. By the end of 2022, the impact of COVID-19 on preterm births had faded, despite an increase in infections caused by the Omicron variant. Vaccines had become widely available as well as effective therapies for COVID-19. New variants had emerged, and more of the population had acquired immunity to SARS-CoV-2. [...] References: Vaccination, immunity, and the changing impact of COVID-19 on infant health. Torche F, Nobles J. Proc Natl Acad Sci U S A. 2023 Dec 5;120(49):e2311573120. doi: 10.1073/pnas.2311573120. Epub 2023 Nov 27. PMID: 38011548.