Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Oct:99:466-472.
doi: 10.1016/j.ijid.2020.08.039. Epub 2020 Aug 20.

COVID-19 epidemic monitoring after non-pharmaceutical interventions: The use of time-varying reproduction number in a country with a large migrant population

Adil Al Wahaibi  1 , Abdullah Al Manji  2 , Amal Al Maani  2 , Bader Al Rawahi  2 , Khalid Al Harthy  2 , Fatma Alyaquobi  2 , Amina Al-Jardani  2 , Eskild Petersen  2 , Seif Al Abri  2
Affiliations

COVID-19 epidemic monitoring after non-pharmaceutical interventions: The use of time-varying reproduction number in a country with a large migrant population

Adil Al Wahaibi et al. Int J Infect Dis. 2020 Oct.

Abstract

Background: COVID-19's emergence carries with it many uncertainties and challenges, including strategies to manage the epidemic. Oman has implemented non-pharmaceutical interventions (NPIs) to mitigate the impact of COVID-19. However, responses to NPIs may be different across different populations within a country with a large number of migrants, such as Oman. This study investigated the different responses to NPIs, and assessed the use of the time-varying reproduction number (Rt) to monitor them.

Methods: Polymerase chain reaction (PCR) laboratory-confirmed COVID-19 data for Oman, from February 24 to June 3, 2020, were used alongside demographic and epidemiological information. Data were arranged into pairs of infector-infectee, and two main libraries of R software were used to estimate reproductive number (Rt). Rt was calculated for both Omanis and non-Omanis.

Findings: A total of 13,538 cases were included, 44.9% of which were Omanis. Among all these cases we identified 2769 infector-infectee pairs for calculating Rt. There was a sharp drop in Rt from 3.7 (95% confidence interval [CI] 2.8-4.6) in mid-March to 1.4 (95% CI 1.2-1.7) in late March in response to NPIs. Rt then decreased further to 1.2 (95% CI 1.1-1.3) in late April after which it rose, corresponding to the easing of NPIs. Comparing the two groups, the response to major public health controls was more evident in Omanis in reducing Rt to 1.09 (95% CI 0.84-1.3) by the end of March.

Interpretation: Use of real-time estimation of Rt allowed us to follow the effects of NPIs. The migrant population responded differently than the Omani population.

Keywords: COVID-19 epidemiology; Public health intervention; Reproductive number.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Daily COVID-19 epidemic curve by date of collection for Omanis compared with non-Omanis, February 24 to June 3, 2020.
Figure 2
Figure 2
Daily COVID-19 epidemic curve with corresponding reproduction number by date of onset for Oman, February 24 to June 3, 2020. The phases of public health control measures are also shown.
Figure 3
Figure 3
Rt trend variation between Omanis and non-Omanis, February 24 to June 3, 2020. The phases of public health control measures and events are also shown. The arrows indicate the start of public health control measures. The mean value corresponds to the start date of the 7-day moving window.
Figure 4
Figure 4
The trend of incidence per 100,000 population (with 95% CI) for daily cases in Omanis and non-Omanis. After June 1, the number of cases that could not be linked to known clusters increased rapidly. A cluster of cases is where more than two cases can be linked to a common index case. A sporadic case is one that cannot be linked to an existing cluster.
See this image and copyright information in PMC

References

    1. Bi Q., Wu Y., Mei S. Epidemiology and transmission of COVID-19 in 391 cases and 1286 of their close contacts in Shenzhen, China: a retrospective cohort study. Lancet Infect Dis. 2020 doi: 10.1016/S1473-3099(20)30287-5. - DOI - PMC - PubMed
    1. Chinazzi M., Davis J.T., Ajelli M. The effect of travel restrictions on the spread of the 2019 novel coronavirus (COVID-19) outbreak. Science. 2020 eaba9757. - PMC - PubMed
    1. Cori A. R Package Version; 2013. EpiEstim: A Package to Estimate Time Varying Reproduction Numbers From Epidemic Curves; p. 1.
    1. Cori A., Ferguson N.M., Fraser C., Cauchemez S. A new framework and software to estimate time-varying reproduction numbers during epidemics. Am J Epidemiol. 2013;178:1505–1512. - PMC - PubMed
    1. Ministry of Health, Singapore. COVID-19 Situation Report. https://covidsitrep.moh.gov.sg/ [Accessed 19 June 2020].