Barbeito, InésPrecioso, DanielSierra, María JoséVegas-Azcárate, SusanaFernández Balbuena, SoniaVitoriano, BegoñaGoméz-Ullate, DavidCao, RicardoMonge Corella, SusanaStudy Group for Non-Pharmaceutical Interventions in Spain2023-04-182023-04-182023-04Front. Public Health. 2023;11:1061331.http://hdl.handle.net/20.500.12105/15833Background: We estimated the association between the level of restriction in nine different fields of activity and SARS-CoV-2 transmissibility in Spain, from 15 September 2020 to 9 May 2021. Methods: A stringency index (0–1) was created for each Spanish province (n = 50) daily. A hierarchical multiplicative model was fitted. The median of coefficients across provinces (95% bootstrap confidence intervals) quantified the effect of increasing one standard deviation in the stringency index over the logarithmic return of the weekly percentage variation of the 7-days SARS-CoV-2 cumulative incidence, lagged 12 days. Results: Overall, increasing restrictions reduced SARS-CoV-2 transmission by 22% (RR = 0.78; one-sided 95%CI: 0, 0.82) in 1 week, with highest effects for culture and leisure 14% (0.86; 0, 0.98), social distancing 13% (0.87; 0, 0.95), indoor restaurants 10% (0.90; 0, 0.95) and indoor sports 6% (0.94; 0, 0.98). In a reduced model with seven fields, culture and leisure no longer had a significant effect while ceremonies decreased transmission by 5% (0.95; 0, 0.96). Models R2 was around 70%. Conclusion: Increased restrictions decreased COVID-19 transmission. Limitations include remaining collinearity between fields, and somewhat artificial quantification of qualitative restrictions, so the exact attribution of the effect to specific areas must be done with caution.engVoRhttp://creativecommons.org/licenses/by/4.0/COVID-19SARS-CoV-2PandemicNon-pharmaceutical interventions (NPI)EffectivenessStringency indexLogarithmic returnHierarchical modelsAtribución 4.0 Internacional11106133110.3389/fpubh.2023.10613312296-2565Frontiers in Public Healthopen access