key: cord-1019916-zclymg50
authors: Zhuang, Zian; Zhao, Shi; Lin, Qianying; Cao, Peihua; Lou, Yijun; Yang, Lin; He, Daihai
title: Preliminary estimation of the novel coronavirus disease (COVID-19) cases in Iran: a modelling analysis based on overseas cases and air travel data
date: 2020-03-06
journal: nan
DOI: 10.1101/2020.03.02.20030320
sha: e5163021a1b88e2c2335cca27fbfcf883f870830
doc_id: 1019916
cord_uid: zclymg50

As of 1 March 2020, Iran has reported 987 COVID-19 cases and including 54 associated deaths. At least six neighboring countries (Bahrain, Iraq, Kuwait, Oman, Afghanistan and Pakistan) have reported imported COVID-19 cases from Iran. We used air travel data and the cases from Iran to other Middle East countries and estimated 16533 (95% CI: 5925, 35538) COVID-19 cases in Iran by 25 February, before UAE and other Gulf Cooperation Council countries suspended inbound and outbound flights from Iran.

In this study, we used the imported cases and air travel data from Iran to other Middle East countries to estimate the number of COVID-19 cases in Iran. Then we compared our estimates with the number of reported cases in Iran to evaluate the extent of under-ascertainment.

We obtained transport capability of international airlines from 30 major airports in Iran from 1 February to 24 February 2020 (WorldData, 2020), from the Variflight platform (https://data.variflight.com/). We collected the number of exported cases from Iran to other countries in the Middle East (World Health Organization, 2020).

Population size of Iran (81,800,269 in 2018) was obtained from the World Bank (https://data.worldbank.org/). Table 1 shows the number of daily population flow and total reported cases of countries used in our calculation.

Following Imai et al.'s (2020), we assumed number of cases (n) exported from Iran follows a Binomial distribution (Bin) with size N and probability p. Here, N represents total number of cases infected in Iran, and p is the probability that one case . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.03.02.20030320 doi: medRxiv preprint is detected overseas. We approximated p by the ratio of daily outbound passengers of Iran (D) over total size of population (M) that those airports serve and multiplying the mean duration (t) from exposure to detection. Thus, p = Dt / M. We set t at 10 days according to (Imai et al., 2020) . We assumed that the catchment population is the total population of Iran. We calculated the maximum likelihood estimates of the total number of COVID-19 cases in Iran (λ) by fitting model to the number of confirmed cases with Binomial-distributed likelihood framework. As shown in Eqn (1),

represents the total log-likelihood and k is the total number of countries we selected.

The 95% confidence intervals (CI) are calculated by using the profile likelihood estimation approach determined by a Chi-square quantile.

To explore more alternative scenarios, we also considered a smaller catchment population (60,000,000) and a shorter detection window (8 days). We considered a baseline scenario with 100% attendance rate for each aircraft as well as other alternative scenarios. In addition, we tested the situation that 90% and 70%

attendance rate for each aircraft, keeping other situation as baseline scenario.

We estimated the total number of cases in Iran was 16533 (95% CI: 5925, 35538) by 25 February 2020. 

The ethical approval or individual consent was not applicable.

All data and materials used in this work were publicly available.

Not applicable.

. CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

is the (which was not peer-reviewed) The copyright holder for this preprint 

Iran says 'tens of thousands' may get tested for coronavirus

Potential for global spread of a novel coronavirus from China. Journal of travel medicine

Estimating the potential total

None.

The funding agencies had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.

Collaborative Research project. Other authors declare no competing interests.. CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.03.02.20030320 doi: medRxiv preprint