The results of this study show that by February 13th, 2020, in Shandong, there were 518 patients confirmed with SARS-Cov-2 and 78 suspected cases (10th in China). Among them, there was no death case. Most patients were middle-aged or young, and the proportion of males was higher than that of females. Additionally, male patients were younger than females. The mode of transmission seems to favor cluster transmission. The onset-diagnosis was reduced as time progressed, probably due to the implemented public health prevention and control measures.
Compared with a previous study by Wang et al. , the confirmed patients in the present study were younger (43 vs. 56 years), but similar to patients from Zhejiang Province (41 years) . The percentage of male patients was higher in confirmed patients (similar between the two studies, at 56% and 54%), and the male-to-female ratio was 1.26:1. In contrast, the male-to-female ratio was 0.85:1 in suspected cases. The sex distribution was different between the confirmed patients and suspected patients, which could be associated with the fact that males have more outdoor activities than females, and thus the risk of exposure was higher, while more females received examinations because of having been in close contacts with carriers.
As time progressed, the cause of the disease changed from a history of traveling in Hubei and other high-prevalence areas [3, 6, 8, 9, 16, 19] to local individuals who were in close contact with the virus carriers. In addition, in accordance with the human-to-human transmission mode of SARS-Cov-2 [3, 6, 8–11], the virus was mainly transmitted among individuals living, working, or traveling together, and there were 99 cluster outbreaks in Shandong province. Li et al. reported in Zhejiang that no patient was ever exposed to the Huanan Seafood Market, and all were due to human-to-human transmission, indicating protective measures should be taken to prevent direct human contact transmission .
The delay between onset and diagnosis dimension with time, which may be due to enhanced awareness and knowledge of the disease, as well as to the strict preventive measures and reporting policies that were implemented in China to face the epidemic [13–15].
Similarly to SARS-CoV, fever and cough were the dominant symptoms, accompanied by chest imaging suggestive of pneumonia [5, 6], but the gastrointestinal symptoms were rare, which is different from SARS-CoV, MERS-CoV, and influenza [23–25]. Of note, the absence of fever is much higher with SARS-Cov-2 than with SARS-CoV and MERS-CoV, suggesting many cases may have been missed since public health surveillance relied heavily on fever detection . In the present study, a small percentage of patients with confirmed infection were in a critical state, but no deaths were reported. The 62 patients from Zhejiang reported in February 2020 were showing relatively mild symptoms . This is lower than the official death toll of 2.01% in China [1, 22]. Nevertheless, since the first case of SARS-Cov-2 was reported relatively late compared with Hubei, the appropriate detection, prevention, and control methods were already implemented [13, 14], which probably led to a reduction in disease severity and mortality due to early diagnosis and management.