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Impact of stringent non-pharmaceutical interventions applied during the second and third COVID-19 epidemic waves in Portugal, 9 November 2020 to 10 February 2021: an ecological study
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View Affiliations Hide AffiliationsAna Rita Torresa.rita.torres insa.min-saude.pt
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Citation style for this article: . Impact of stringent non-pharmaceutical interventions applied during the second and third COVID-19 epidemic waves in Portugal, 9 November 2020 to 10 February 2021: an ecological study. Euro Surveill. 2022;27(23):pii=2100497. https://doi.org/10.2807/1560-7917.ES.2022.27.23.2100497 Received: 21 Mar 2021; Accepted: 21 Jan 2022
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Abstract
Non-pharmaceutical interventions (NPIs) were implemented worldwide to control the spread of SARS-CoV-2.
To evaluate the impact of tiered NPIs and a nationwide lockdown on reduction of COVID-19 incidence during the second and third epidemic waves in Portugal.
Surveillance data on laboratory-confirmed COVID-19 cases were used to conduct an interrupted time series analysis to estimate changes in daily incidence during a second wave tiered NPI period (9 November–18 December 2020), and a third wave lockdown period without (15–21 January 2021) and with school closure (22 January–10 February 2021).
Significant changes in trends were observed for the overall incidence rate; declining trends were observed for tiered NPIs (−1.9% per day; incidence rate ratio (IRR): 0.981; 95% confidence interval (CI): 0.973–0.989) and a lockdown period without (−3.4% per day; IRR: 0.966; 95% CI: 0.935–0.998) and with school closure (−10.3% per day, IRR: 0.897; 95% CI: 0.846–0.951). Absolute effects associated with tiered NPIs and a lockdown on a subsequent 14-day period yielded 137 cases and 437 cases per 100,000 population potentially averted, respectively.
Our results indicate that tiered NPIs implemented during the second wave caused a decline in COVID-19 incidence, although modest. Moreover, a third wave lockdown without school closure was effective in reducing COVID-19 incidence, but the addition of school closure provided the strongest effect. These findings emphasise the importance of early and assertive decision-making to control the pandemic.
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