Journal Article

Changing patterns of SARS-CoV-2 infection through Delta and Omicron waves by vaccination status, previous infection and neighbourhood deprivation: a cohort analysis of 2.7 M people

Semple, Malcolm G., Ashton, Matthew, Turtle, Lance, Buchan, Iain, Green, Mark A., Garcia-Fiñana, Marta, Hungerford, Daniel J., Cheyne, Christopher, Leeming, Gary, Singleton, Alex, Hughes, David M.

2022

Overview

Background Our study examines if SARS-CoV-2 infections varied by vaccination status, if an individual had previously tested positive and by neighbourhood socioeconomic deprivation across the Delta and Omicron epidemic waves of SARS-CoV-2. Methods Population cohort study using electronic health records for 2.7 M residents in Cheshire and Merseyside, England (3rd June 2021 to 1st March 2022). Our outcome variable was registered positive test for SARS-CoV-2. Explanatory variables were vaccination status, previous registered positive test and neighbourhood socioeconomic deprivation. Cox regression models were used to analyse associations. Results Originally higher SARS-CoV-2 rates in the most socioeconomically deprived neighbourhoods changed to being higher in the least deprived neighbourhoods from the 1st September 2021, and were inconsistent during the Omicron wave. Individuals who were fully vaccinated (two doses) were associated with fewer registered positive tests (e.g., individuals engaged in testing between 1st September and 27th November 2021—Hazards Ratio (HR) = 0.48, 95% Confidence Intervals (CIs) = 0.47–0.50. Individuals with a previous registered positive test were also less likely to have a registered positive test (e.g., individuals engaged in testing between 1st September and 27th November 2021—HR = 0.16, 95% CIs = 0.15–0.18. However, the Omicron period saw smaller effect sizes for both vaccination status and previous registered positive test. Conclusions Changing patterns of SARS-CoV-2 infections during the Delta and Omicron waves reveals a dynamic pandemic that continues to affect diverse communities in sometimes unexpected ways.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Adaptive immunity / Bias / Cohort analysis / Cohort Studies / Confidence intervals / Coronaviruses / COVID-19 / COVID-19 - epidemiology / COVID-19 - prevention & control / COVID-19 vaccines / Deprivation / Economic aspects / Electronic health records / Electronic medical records / Ethnicity / Health care disparities / Humans / Inequality / Infections / Infectious Diseases / Influenza / Internal Medicine / Medical Microbiology / Medicine / Medicine & Public Health / Missing data / Neighborhoods / Pandemics / Parasitology / Population / Population studies / Regression analysis / Regression models / SARS-CoV-2 / Sensitivity analysis / Severe acute respiratory syndrome coronavirus 2 / Social aspects / Social research / Socioeconomics / Statistical analysis / Statistics / Tropical Medicine / Vaccination / Variables / Viral diseases