The Impact of the Social Distancing Policy on COVID-19 Incidence Cases and Deaths in Iran from February 2020 to January 2021: Insights from an Interrupted Time Series Analysis

Abstract

Background: In December 2019, a viral outbreak occurred in China, and rapidly spread out worldwide. Due to the lack of immediately available vaccines and effective drugs, many policy- and decision-makers have focused on non-pharmacological methods, including social distancing. This study was aimed at assessing the effects of the implementation of this policy in Iran, one of the countries most affected by COVID-19. We conducted a quasi-experimental study, utilizing the interrupted time series analysis (ITSA) approach. Methods: We collected daily data between February 20, 2020 and January 29, 2021, through governmental websites from 954 public hospitals and healthcare settings. The Iranian government launched the social distancing policy on March 27, 2020. Statistical analyses, including ITSA, were carried out with R software Version 3.6.1 (London, UK). Results: During the study period, 1,398,835 confirmed incidence cases and 57,734 deaths occurred. We found a decrease of -179.93 (95% CI: -380.11 to -20.25, P-value=0.078) confirmed incidence cases following the implementation of the social distancing policy, corresponding to a daily decrease in the trend of -31.17 (95% CI: -46.95 to -15.40, P-value=0.08). Moreover, we found a decrease of -28.28 (95% CI: -43.55 to -13.01, P-value=0.05) deaths, corresponding to a daily decrease in the trend of -4.52 (95% CI: -5.25 to -3.78, P-value=0.003). Conclusion: The growth rate of confirmed incidence cases and deaths from COVID-19 in Iran has decreased from March 27, 2020 to January 29, 2021, after the implementation of social distancing. By implementing this policy in all countries, the burden of COVID-19 may be mitigated.

Keywords: COVID-19; Iran; interrupted time series analysis; pandemics; social distancing policy.

Figure 1

The rate of confirmed COVID-19 incidence cases between February 20^th, 2020 and January 29^th, 2021, prior to and following the implementation of the social distancing policy in Iran (launched on March 27^th 2020). Dashed line is projected trend without the implementation of the policy; solid line is the trend observed after the implementation of the policy.

Figure 2

The rate of deaths related to COVID-19 between February 20^th, 2020 and January 29^th, 2021, prior to and following the implementation of the social distancing policy in Iran (launched on March 27^th 2020). Dashed line is projected trend without the implementation of the policy; solid line is the trend observed after the implementation of the policy.

Figure 3

Residuals from the OLS regression (A: COVID-19 confirmed incidence cases, B: deaths between February 20^th, 2020 and January 29^th, 2021, in Iran). The plot shows presence of correlation.

Figure 4

Autocorrelation and partial autocorrelation function (A: confirmed incidence cases, B: deaths between February 20^th, 2020 and January 29^th, 2021, in Iran). The plots show presence of correlation.