Human coronavirus is one of the pathogens that causes respiratory tract infection. Before the discovery of the novel coronavirus that caused this outbreak, six other coronaviruses were known to infect humans: HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, SARS-CoV, and MERS-CoV. Respiratory diseases caused by four types of coronavirus, HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1, are generally mild, while both SARS-CoV and MERS-CoV are highly infectious and pathogenic and have caused epidemics or outbreaks [6–8]. The present novel coronavirus has the typical characteristics of the coronavirus family and belongs to the beta - coronavirus, which is the closest genome-wide relative of the SARS-like coronavirus strain RaTG13 carried by bats, with a homology of 96% . At present, the COVID-19 epidemic in China has been significantly mitigated under strict and active prevention and control measures . By March 4, 2020, all COVID-19 patients admitted to the hospital Xiamen had been discharged. The following includes an analysis of the clinical characteristics of these patients.
The cases in Xiamen involved eight family clusters, which clearly indicates that coronavirus presents the capacity for human-to-human transmission, consistent with previous reports . Further study must focus on the spread of the virus, such as its propagation mode and transmission by different types of specimens (e.g., upper and lower respiratory tract, saliva, feces, and urine).
According to the case data reported in this paper, by comparing the characteristics of previously reported cases in Wuhan [1–3], we found that the severity of cases in Xiamen was less than that in Wuhan, which is mainly reflected by that the proportions of patients with the severe and critical disease types were lower and the proportion of patients requiring organ support technology was lower. Huang et al.  reported 41 cases of Wuhan COVID-19 patients, including 13 (32%) who required ICU care, 2 (5%) who received invasive ventilator-assisted ventilation, 2 (5%) who underwent ECMO, and 6 (15%) who died. Separately, Wang et al.  provided details of 138 cases of Wuhan COVID-19 patients, with 36 cases (26%) requiring ICU care, 17 cases (12%) receiving invasive ventilator-assisted ventilation, 4 cases (3%) using ECMO, and 6 cases (4.3%) who died. In our study, a total of 35 COVID-19 patients were admitted and discharged from the hospital in Xiamen, among which seven (20%) cases required ICU care. There were no patients requiring invasive ventilator-assisted ventilation, CRRT, or ECMO. Also, there were no deaths, no nosocomial infections, or infections of medical staff. Importantly, our study offers a more complete picture of the long-term outcomes relative to the two aforementioned studies. These cases reported from Wuhan were during the earlier stage of the outbreak of COVID-19, so the pathogenicity and infectivity of the virus were not fully recognized. In addition, the number of COVID-19 patients diagnosed in Wuhan was too high to achieve early and timely treatment. However, before the first confirmed case of COVID 19 appeared in Xiamen, the Xiamen municipal government had already attached great importance to its management and adopted all-out efforts to prevent and control the spread of the disease. The government also preemptively established a designated hospital for the treatment of novel coronavirus. From January 15, 2020, onward, 21 outpatient clinics for fever were set up. Wang et al.  also reported in their study that the duration of hospitalization from symptom onset to hospital admission among their Wuhan cases was seven (4–8) days, while the duration among the Xiamen cases was two (1–4) days, without no nosocomial infections, infections of the medical staff infection, or deaths. The above facts suggest that the Xiamen municipal government achieved the eight goals of early and concentrated mitigation —that is, early detection, early report, early diagnosis, and early isolation as well as centralizing patients, centralizing experts, centralizing resources, and centralizing treatment while also directing the concentration of severe patients to the best comprehensive medical institutions, thus improving the rates of hospitalization and cure and reducing the infection and mortality rates. In the literature, the global mortality of MERS-CoV cases is about 34.4% , and the mortality of the next generation of disease is expected to be 20.4% , suggesting that, with the spread of transmission, novel coronavirus also shows the potential that its infectivity and pathogenicity would be gradually weakened.
When compared with patients in the general-ward group, the patients in the ICU group had higher maximum body temperatures and longer fevers after admission, suggesting that if the patients experienced repeated high fevers without alleviation, such were manifestations of severe disease. During the laboratory examination, we found that many patients had low blood lymphocyte ratios and lymphocyte counts at the time of admission, but there was no significant difference observed in either regard between the general-ward group and the ICU group. However, by five to seven days after admission, the blood lymphocyte ratios and lymphocyte counts of the ICU group were still low, while the general-ward group’s results normalized, resulting in a significant difference between the general-ward group and the ICU group. Thus, we can draw a conclusion that persistent low or gradual decline in the level of lymphocytes suggests a poor prognosis. Meanwhile, relative to patients in the general-ward group, patients in the ICU group had higher CRP and lactate dehydrogenase levels, suggesting that the above indicators may also be clinical warning indicators of severe disease, which is consistent with China’s novel coronavirus pneumonia diagnosis and treatment scheme (seventh edition) .
Lung CT findings included mainly bilateral multiple lesions (86%), subpleural distribution (97%), and ground-glass shadow (71%), which were consistent with details in previous reports [1–3].Novel coronavirus nucleic acid testing showed three cases (6%) requiring three or more nucleic acid tests before being ruled positive, and one case required six nucleic acid tests before being ruled positive. Thus, if the patient has an epidemiological history, respiratory symptoms, and typical pulmonary CT imaging changes such as multiple subpleural distributions of ground-glass shadow, even if the novel coronavirus nucleic acid test was negative twice, it was believed to still be necessary to continue nucleic acid testing to reduce the rate of missed diagnosis. In addition, we found that one patient still had a positive nucleic acid report after 14 nucleic acid tests, but the day after nasal irrigation, the nucleic acid test results from the nasal swab turned negative; at the same time, the patient had no symptoms, and the lung lesions had been completely absorbed for five days. Considering the possible reasons for this, when a patient has a nasal scab or sinus inflammation, it can result in the continuous presence of localized viral nucleic acids; however, in such a case, there is no virus activity in the body. At this time, nucleic acid detection should be performed on alternate days after nasal cleansing.
Treatment is mainly based on the novel coronavirus pneumonia diagnosis and treatment scheme developed by the national health board. However, up to now, there has been no effective medicine available for novel coronavirus, which is mainly treated by strengthening supportive treatment, the timely provision of effective oxygen therapy, and maintenance of a stable internal environment.
Our study has several limitations. First, we included only 35 cases—and fewer patients in the ICU group in particular—so we need to be cautious about the indicators used for clinical early warning purposes. Second, we listed some abnormal clinical manifestations and gave some possible explanations, but, due to the small sample size, the real reasons for these manifestations need to be further studied. Third, we used data from a single city outside Wuhan. More data collected from other cities outside Wuhan may be needed to evaluate the real differences between the cases in Wuhan and those outside Wuhan.