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Volume 29, Number 1—January 2023
Research

Effects of Second Dose of SARS-CoV-2 Vaccination on Household Transmission, England

Asad Zaidi, Ross Harris, Jennifer Hall, Sarah Woodhall, Nick Andrews, Kevin Dunbar, Jamie Lopez-Bernal, and Gavin DabreraComments to Author 
Author affiliations: COVID-19 Vaccines and Epidemiology Division—UK Health Security Agency, London, UK (A. Zaidi, J. Hall, S. Woodhall, G. Dabrera); Statistics, Modelling, and Economics Department—UK Health Security Agency (R. Harris, N. Andrews); Institute for Women’s Health, University College, London (J. Hall); Immunisation and Countermeasures Division—UK Health Security Agency (K. Dunbar, J. Lopez-Bernal)

Main Article

Table

Adjusted hazard ratios for household contacts of persons with COVID becoming a secondary case by inclusion criteria for different models

Period Vaccine Analysis model HR (95% CI)
A, never vaccinated B, not vaccinated before index case C, vaccinated after index case D, unvaccinated contacts only E, cohort
Feb-May ChAdOx1 0.54 (0.41–0.69) 0.50 (0.38–0.64) 0.50 (0.38–0.65) 0.48 (0.37–0.64) 0.53 (0.43–0.66)
BNT162b2
 0.19 (0.13–0.28)
 0.18 (0.12–0.26)
 0.18 (0.12–0.26)
 0.14 (0.09–0.23)
 0.19 (0.13–0.26)
Jun-Sep ChAdOx1 1.06 (1.04–1.08) 1.06 (1.04–1.08) 0.94 (0.88–1.00) 0.84 (0.76–0.92) 1.08 (1.06–1.10)
BNT162b2 0.74 (0.72–0.76) 0.74 (0.73–0.76) 0.66 (0.62–0.71) 0.56 (0.51–0.62) 0.76 (0.74–0.78)
mRNA-1273 0.36 (0.29–0.45) 0.36 (0.29–0.45) 0.31 (0.25–0.39) 0.30 (0.22–0.40) 0.380.30–0.47)

*For models A–D, we used a stratified Cox model with adjustment, and different inclusion criteria for contacts and of the baseline group of contacts of unvaccinated index cases. Model E has the same inclusion criteria as model A, but uses a cohort model with all covariates entered as adjustment variables, rather than stratification. HR, hazard ratio.

Main Article

Page created: December 09, 2022
Page updated: December 21, 2022
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