News Scan for May 31, 2022

Study: Vaccine could have averted 75% of COVID deaths in some Chicago areasAbout 75% of COVID-19 deaths in the least-vaccinated Chicago areas could have been prevented if their uptake would have equaled that of the highest-coverage areas during the Alpha and Delta variant surges, suggests a study late last week in JAMA Network Open.University of Chicago researchers studied vaccine uptake and outcomes of 2,686,355 Chicago residents of 52 ZIP codes using data from the Chicago Department of Public Health and the Cook County Medical Examiner from Mar 1, 2020, to Nov 6, 2021.Median age was 34 years, 51% were women, 29% were Hispanic, 29% were Black, and 33% were White.

Of residents of areas with the lowest vaccination rates, 80% were Black, compared with 8% of those in the most-vaccinated quartile.After the researchers controlled for age distribution and recovery from infection, they found that a 10-percentage-point increase in ZIP code–level vaccination 6 weeks before the Alpha peak was tied to a 39% lower relative risk of death (incidence rate ratio [IRR], 0.61; 95% confidence interval [CI], 0.52 to 0.72).Similarly, a 10-percentage-point increase in vaccination 6 weeks before Delta peaked was linked to a 24% lower risk of COVID-19 death (IRR, 0.76; 95% CI, 0.66 to 0.87).

A difference-in-difference analysis showed that 119 Alpha deaths (72%; 95% CI, 63% to 81%]) and 108 Delta deaths (75%; 95% CI, 66% to 84%]) could have been prevented in the least-vaccinated quartile if uptake has been that of the most-vaccinated quartile."Prior to the vaccination campaign, there existed consistent parallel trends in pandemic mortality between the different parts of the city," the study authors wrote. "During the Alpha wave, a large gap in