Epidemic Potential of COVID-19 in Omsk Region during Anti-Epidemic Measures

Aim. To study the spread of COVID-19 among the population of the Omsk Region during 24 weeks of the epidemic on the background of anti-epidemic measures.

Materials and methods. A descriptive epidemiological study was carried out based on publically available data и data from the Center for Hygiene and Epidemiology in the Omsk Region on the official registration and epidemiological investigation of detected COVID-19 cases in the Omsk Region for the period from March 27 to September 10, 2020. To assess the potential of COVID-19 to spread, the following indicators were calculated: exponential growth rate (r), basic reproduction number (R0), effective reproduction number (Rt), expected natural epidemic size and herd immunity threshold. Data processing was performed using MS Excel 2010. The cartogram was built using the QGIS 3.12-Bukuresti application in the EPSG: 3576 coordinate system.

Results and discussion. For the period from March 27 to September 10, 2020, a total of 9779 cases of COVID-19 were registered in the Omsk Region, the cumulative incidence was 507,6 per 100000 (95 % CI 497,5÷517,6), the case-fatality rate for completed cases was 2.9 %, for identified cases – 2.4 %. The most active spread of COVID-19 was noted in Omsk and 4 out of 32 districts of the region (Moskalensky, Azov German National, Mariyanovsky, Novovarshavsky). During the ongoing anti-epidemic measures, the exponential growth rate of the cumulative number of COVID-19 cases was 4.5 % per day, R0 – 1.4–1.5, Rt – 1.10, herd immunity threshold – 28.6 %. The expected size of the epidemic in case of sustained anti-epidemic measures can reach 58.0 % of the recovered population. A decrease in the number of detected virus carriers, incomplete detection of COVID-19 among patients with community-acquired pneumonia introduced additional risks for the latent spread of infection and complications of the epidemic situation. Maintaining restrictive  measures and increasing the proportion of the immune population (over 28.6 %) may significantly reduce the risks of increasing the spread of COVID-19 in the Omsk Region. 

1. WHO. WHO Director-General's opening remarks at the media briefing on COVID19 – 11 March 2020. (Cited 29.07.20) [Internet]. Available from: https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-oncovid-19---11-march-2020.

2. WHO. WHO Director-General's opening remarks at the media briefing on COVID19 – 11 March 2020. (Cited 29.07.20) [Internet]. Available from: https://www.who.int/dg/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-oncovid-19---11-march-2020.

3. WHO. Coronavirus disease (COVID-19). Situation Report – 46. (Cited 29.07.20) [Internet]. Available from: https://www.who.int/docs/default-source/coronavirus/situation-reports/20200306-sitrep-46-covid-19.pdf?sfvrsn=96b04adf_4.

4. WHO. Coronavirus disease (COVID-19). Dashboard. (Cited 13.09.20) [Internet]. Available from: https://covid19.who.int/table?tableDay=yesterday&tableChartType=heat.

5. WHO. Coronavirus disease (COVID-19). Dashboard. (Cited 13.09.20) [Internet]. Available from: https://covid19.who.int/table?tableDay=yesterday&tableChartType=heat.

6. Wallinga J., Lipsitch M. How generation intervals shape the relationship between growth rates and reproductive numbers. Proc. Biol. Sci. 2007; 274(1609):599–604. DOI: 10.1098/rspb.2006.3754.

7. Wallinga J., Lipsitch M. How generation intervals shape the relationship between growth rates and reproductive numbers. Proc. Biol. Sci. 2007; 274(1609):599–604. DOI: 10.1098/rspb.2006.3754.

8. Nishiura H., Linton N.M., Akhmetzhanov A.R. Serial interval of novel coronavirus (COVID-19) infections. Int. J. Infect. Dis. 2020; 93:284–6. DOI: 10.1016/j.ijid.2020.02.060.

9. Nishiura H., Linton N.M., Akhmetzhanov A.R. Serial interval of novel coronavirus (COVID-19) infections. Int. J. Infect. Dis. 2020; 93:284–6. DOI: 10.1016/j.ijid.2020.02.060.

10. Park M., Cook A.R., Lim J.T., Sun Y., Dickens B.L. A systematic review of COVID-19 epidemiology based on current evidence. J. Clin. Med. 2020; 9(4):967. DOI: 10.3390/jcm9040967.

11. Park M., Cook A.R., Lim J.T., Sun Y., Dickens B.L. A systematic review of COVID-19 epidemiology based on current evidence. J. Clin. Med. 2020; 9(4):967. DOI: 10.3390/jcm9040967.

12. Miller J.C. A note on the derivation of epidemic final sizes. Bull. Math. Biol. 2012; 74(9):2125–41. DOI: 10.1007/s11538-12-9749-6.

13. Miller J.C. A note on the derivation of epidemic final sizes. Bull. Math. Biol. 2012; 74(9):2125–41. DOI: 10.1007/s11538-12-9749-6.

14. Rodpothong P., Auewarakul P. Viral evolution and transmission effectiveness. World J. Virol. 2012; 1(5):131–4. DOI: 10.5501/wjv.v1.i5.131.

15. Rodpothong P., Auewarakul P. Viral evolution and transmission effectiveness. World J. Virol. 2012; 1(5):131–4. DOI: 10.5501/wjv.v1.i5.131.

16. 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(9):1505–12. DOI: 10.1093/aje/kwt133.

17. 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(9):1505–12. DOI: 10.1093/aje/kwt133.

18. Stolwijk A.M., Straatman H., Zielhuis G.A. Studying seasonality by using sine and cosine functions in regression analysis. J. Epidemiol. Community Health. 1999; 53(4):235–8. DOI: 10.1136/jech.53.4.235.

19. Stolwijk A.M., Straatman H., Zielhuis G.A. Studying seasonality by using sine and cosine functions in regression analysis. J. Epidemiol. Community Health. 1999; 53(4):235–8. DOI: 10.1136/jech.53.4.235.

20. WHO. Coronavirus disease (COVID-19). Situation Report – 46. (Cited 29.07.20) [Internet]. Available from: https://www.who.int/docs/default-source/coronavirus/situation-reports/20200306-sitrep-46-covid-19.pdf?sfvrsn=96b04adf_4.

21. WHO. Coronavirus disease (COVID-19). Situation Report – 46. (Cited 29.07.20) [Internet]. Available from: https://www.who.int/docs/default-source/coronavirus/situation-reports/20200306-sitrep-46-covid-19.pdf?sfvrsn=96b04adf_4.