The added effect of non-pharmaceutical interventions and lifestyle behaviors on vaccine effectiveness against severe COVID-19 in Chile: A matched case-double control study

Cinthya Urquidi, Emilio Santelices, Anne J. Lagomarcino, María Teresa Valenzuela, Nicolás Larrañaga, Emilio Gonzalez, Axel Pavez, Amanda Wosiack, Marcela Maturana, Paulina Moller, Juan Pablo Torres, Sergio Muñoz, Miguel O'Ryan G*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Background: World Health Organization approved vaccines have demonstrated relatively high protection against moderate to severe COVID-19. Prospective vaccine effectiveness (VE) designs with first-hand data and population-based controls are nevertheless rare. Neighborhood compared to hospitalized controls, may differ in compliance to non-pharmacuetical interventions (NPI) compliance, which may influence VE results in real-world settings. We aimed to determine VE against COVID-19 intensive-care-unit (ICU) admission using hospital and community-matched controls in a prospective design. Methods: We conducted a multicenter, observational study of matched cases and controls (1:3) in adults ≧18 years of age from May to July 2021. For each case, a hospital control and two community controls were matched by age, gender, and hospital admission date or neighborhood of residence. Conditional logistic regression models were built, including interaction terms between NPIs, lifestyle behaviors, and vaccination status; the model's β coefficients represent the added effect these terms had on COVID-19 VE. Results: Cases and controls differed in several factors including education level, obesity prevalence, and behaviors such as compliance with routine vaccinations, use of facemasks, and routine handwashing. VE was 98·2% for full primary vaccination and 85·6% for partial vaccination when compared to community controls, and somewhat lower, albeit not significantly, compared to hospital controls. A significant added effect to vaccination in reducing COVID-19 ICU admission was regular facemask use and VE was higher among individuals non-compliant with the national vaccine program, and/or tonroutine medical visits during the prior year. Conclusion: VE against COVID-19 ICU admission in this stringent prospective case-double control study reached 98% two weeks after full primary vaccination, confirming the high effectiveness provided by earlier studies. Face mask use and hand washing were independent protective factors, the former adding additional benefit to VE. VE was significantly higher in subjects with increased risk behaviors.

Original languageEnglish
Pages (from-to)2947-2955
Number of pages9
JournalVaccine
Volume41
Issue number18
DOIs
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 Elsevier Ltd

Keywords

  • COVID-19
  • Non-pharmacological intervention
  • Risk factors
  • SARS-Cov-2
  • Vaccine effectiveness

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