Preliminary estimation of the novel coronavirus disease (COVID-19) cases in Iran: A reply to Sharifi

Authors: Zian Zhuang, Shi Zhao, Qianying Lin, Peihua Cao, Yijun Lou, Lin Yang, Daihai He

The worldwide outbreak of the novel coronavirus (SARS-Cov-2) pneumonia remains a major public health concern. We thank Sharifi et al.’s comments to our recent study (Zhuang et al., 2020). In that paper we adopted the similar method as Imai’s (Imai et al., 2020), which was used to estimate the number of COVID-19 cases in the early stages of the COVID-19 outbreak in Wuhan, Hubei, China. The model provided a rough range estimation about the epidemic size and has been recognized by peers as a valid method in the early stage of an epidemic (Kucharski et al., 2020, Boldog et al., 2020, Ng et al., 2020). The accumulated evidence coincides with early estimation in scales. The estimation of the total infected cases could be improved if more evidence is available. We had discussed alternative scenarios (Zhuang et al., 2020) including smaller catchment population (e.g., 75% of the population), shorter detection window (e.g. different generation interval), different load factors of planes. A lower estimation of total infected cases is possible under the scenario in which a smaller catchment population is linked to those airports. Nevertheless, there are no solid evidence which specific scenario would be the reality now. Thus, we listed results under all scenarios. It is a weak argument that international flight travelers have a more extensive local social network, as they might have a smaller local social network due to losing connections while living overseas. Some social studies may be helpful to determine which is more reasonable. The report from Statistical center of Iran (Statistical center of Iran, 2018) supports that over 25% of the whole population live in rural area. However, according to the same reference (Statistical center of Iran, 2018), population size of the age group 1-14 is around 4% larger in rural areas, compared to the urban areas. This situation is likely to be a factor in reducing the onset of infection symptoms among rural population, since most of COVID-19 patients were aged from 30 to 79 (87%) (Wu and McGoogan, 2020). Rural areas may be less dense compared to urban areas which is likely to result in decreased average number of effective contacts. Also, it is likely that there are not as many tests available for the rural population. Hence, overall, lower prevalence of infection in rural areas does not strongly reject the assumption that flight passengers are distributed homogeneously among rural and urban population.

تاریخ انتشار اولیه: ۱۱ اردیبهشت ۱۳۹۹
تاریخ رصد: ۱۱ شهریور ۱۳۹۹


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