The current study aimed to describe the clinical outcome and report the incidence of COVID-19 in Isfahan province. The incidence of COVID-19 in a four-month time interval was 25.4% among screened patients; this incidence was 2.1 per 1000 person among whole province population.
Authors of the paper believe their results are reliable and valid because of prospective cohort design, relatively large number of screened people, covering of all health centres and in turn, the whole cities and hospitals, and data quality control by two member of research project who are a panel member of province coronavirus data collection team.
The incidence of COVID-19 in a four-month time interval was 25.4% among screened patient that was consistent with the results of the study by Arab-Mazar, which mapped the incidence of COVID-19 in Iran (15).
Our result showed that the median age of the patient was 45.5 years (Table 1), that was lower than the result of Guan et al. (47 years) (16), Wu et al. (46.1 years) (17), Pan et al. (52.9) (18), Chen et al. (62.0 years) (19). However, our result was inconsistent with the result of the study in Iran by Shahriarirad et al. (53.0 years) (12) Nikpouraghdam et al. (56.0 years) (11) and Araban et al. (56.9 years) (13).
Most (53.9%) of the patients in this study were male (Table 1). Which nearly consistent with Guan et al. (57.9%) (16), Pan et al. (52.5%), Chen et al. (62.4%) (19), and the result of Nikpouraghdam et al. (66.0%) (11), Araban et al. (58.0%) (13) and Shahriarirad et al. (62.8%) (12) study also the result of Wu et al. showed that the proportion of men was lower than women’s (48.75% male) (17).
The result of our study showed that the CFR of COVID-19 was 4.8% (Table 1) which was consistent with the result of Wang et al. (4.3%) (9), Mei et al. (3.6%) (20), and Cai et al. (5.0%) (20) study; however it was higher than the result of Wang et al. (2.8%) (21), Shim et al. (0.7%) (22), and Li et al. (1.1%) (2); and lower than the result of Liu et al. (11.8%) (23), Barrasa et al. (13.0%) (24), Grasselli (15.0%) (25), and Grein et al. (18.0%) (26) study. Different reports on CFR was seen in different studies. The difference between the findings may be due to the age of the participants. In previous studies with higher CFR, the participants age was higher than the present study (23–26). Also, some studies were performed on hospitalized participants (23, 24, 26), while the present study was conducted in health centers, where the cases of the client have a non-severe disease. Some studies may also report low fatality rates due to the high screening rate in the study country and the detection of patients with mild symptoms (22).
Based on the spatial model of the distribution of cases in a four-month time interval, Khansar (469 per 100,000) and Aradestan (355 per 100,000) county had the highest proportion of COVID-19 cases of all the counties (Table 2). This may be due to the lack of enough health facilities and immigration in of suspected cases.
Also, our result showed that most of the imported cases were from the of Najafabad, Khomeini-Shahr, and Shahinshahr&Maymeh. The incidence of COVID-19 in these cities in the four-months was about 246 per 100,000 people (Table 3). It seems this migration was due to the proximity of these counties to Isfahan (average distance of 32 km), more facilities in Isfahan (27), and the low capacity of hospitals in these cities (about 126 hospital-beds). Another reason for importing cases was the reduction of travel restrictions since April 15. Our results showed that 77.3% of the cases imported to Isfahan after the reduction of intra province travel restrictions (lockdown) (Fig. 2) (28).
The results of our study showed that most of the COVID-19 cases imported from Chaharmahal&Bakhtiari (n = 38) and Khuzestan (n = 36) provinces (Table 4). Also, our results show that about 83% of cases has been imported since April 20 (Fig. 2), That restriction on inter-provincial travel was removed and public transportation such as buses, trains and airlines get started (29).
Despite health advice, there are no restrictions on inter-provincial travel. Isfahan is one of the most famous tourist destinations in Iran. It seems that the trend of importing cases and the prevalence of this disease in the Isfahan will increase in the coming months. Although many cases do not show symptoms, they can spread the virus to susceptible individuals (30). It seems that Isfahan's neighboring provinces have a tremendous impact due to the higher volume of traveling to Isfahan.
Limitation
The study has very strong components including the study design that is prospective cohort study, and the sample size was large enough, so the reproducibility of the results is acceptable. In addition, the use of multi-center data increases the generalizability of the findings to the population. However, the main pitfall of the study is lack of knowledge on whom migrated to other provinces. The paper also suffers from lack of clinical and lifestyle factors (such as smoking status, comorbidity with other diseases, Socio-Economic Status (SES)) information on coronavirus cases. Other limitations of this study was the high number of invalid PCR tests. We try to collect more background, lifestyle factors, and clinical and biological data and provide a new report soon.