News briefs

No link between COVID‐19 vaccines and early pregnancy loss

An international study, published in the New England Journal of Medicine, has found no link between COVID‐19 vaccinations and miscarriages early in pregnancy. Using Norwegian registries on first trimester pregnancies, COVID‐19 vaccinations and relevant health conditions, the researchers analysed data on a group of women who had been vaccinated in the weeks leading up to either a miscarriage or an ongoing pregnancy. The researchers found no evidence of a link between the vaccination and miscarriages, which adds to a growing list of research supporting the safety of vaccinations for pregnant women. “Among 13 956 women with ongoing pregnancies (of whom 5.5% were vaccinated) and 4521 women with miscarriages (of whom 5.1% were vaccinated), the median number of days between vaccination and miscarriage or confirmation of ongoing pregnancy was 19. Among women with miscarriages, the adjusted odds ratios for COVID‐19 vaccination were 0.91 (95% confidence interval [CI], 0.75 to 1.10) for vaccination in the previous 3 weeks and 0.81 (95% CI, 0.69 to 0.95) for vaccination in the previous 5 weeks. The results were similar in an analysis that included all available vaccine types, in an analysis stratified according to the number of doses received (one or two), and in sensitivity analyses limited to health care personnel (for whom vaccination was routinely recommended other than in the first trimester) or women with at least 8 weeks of follow‐up after confirmed pregnancy (to exclude subsequent pregnancy loss).” The researchers wrote that their study “found no evidence of an increased risk for early pregnancy loss after Covid‐19 vaccination and adds to the findings from other reports supporting Covid‐19 vaccination during pregnancy.”

https://www.nejm.org/doi/10.1056/NEJMc2114466

Pfizer 90% effective in preventing COVID‐19 in teenagers

An Israeli study, published in the New England Journal of Medicine, has shown that at its peak, the Pfizer COVID‐19 vaccine is 90% effective at preventing COVID‐19 infection in children aged 12 to 18 years. Researchers compared infection rates in about 100 000 vaccinated teens in Israel and a similar unvaccinated cohort. From a week to 21 days after the second dose, the researchers found the vaccine was 90% effective at preventing infection and 93% effective against symptomatic COVID‐19. During the period of the study, 95% of infections in Israel were from the Delta variant. “Of 184 905 vaccinated adolescents, 130 464 met the eligibility requirements, and 94 354 of these vaccine recipients were successfully matched with 94 354 unvaccinated controls.” The authors found that the “estimated vaccine effectiveness against documented SARS‐CoV‐2 infection was 59% (95% confidence interval [CI], 52 to 65) on days 14 through 20 after the first dose, 66% (95% CI, 59 to 72) on days 21 to 27 after the first dose, and 90% (95% CI, 88 to 92) on days 7 to 21 after the second dose. The estimated vaccine effectiveness against symptomatic COVID‐19 was 57% (95% CI, 39 to 71) on days 14 to 20 after the first dose, 82% (95% CI, 73 to 91) on days 21 to 27 after the first dose, and 93% (95% CI, 88 to 97) on days 7 to 21 after the second dose.” They concluded that their results “show that the BNT162b2 mRNA vaccine was highly effective in the first few weeks after vaccination against both documented infection and symptomatic COVID‐19 with the delta variant among adolescents between the ages of 12 and 18 years.”

https://www.nejm.org/doi/10.1056/NEJMc2114290