Covid-19 has been a public health emergency of international concern .The population is lack of immune to Covid-19 and generally susceptible. Covid-19 has rapidly spread to the whole country, which has exceeded the total number of patients with severe acute respiratory syndrome (SARS) in 2003, and the number of confirmed and suspected cases is increasing.
At onset, most cases are mild and the survival rate is high. Once the disease aggravate, the death rate will rise . Early diagnosis, early recognition and early treatment of Covid-19 are particularly important .
At present, most descriptive studies divide patients into general group, severe group and critical group according to diagnostic criteria . Oxygenation Index < 300 mmHg is the criteria to classify general group and severe group. We chose the lower limit of the normal OI (400 mmHg) as group criteria, hoping to help early recognition and high vigilance on the transition from general type to severe type.
The dynamic data about the whole disease process was not much. We tracked and analyzed 38 patients’ all examination results during the whole process of the disease, made dynamic charts, aiming to find the dynamic evolution of different groups through statistical analysis.
Most patients (37/38) in this group had obvious epidemiological characteristics. Before January 24, 2020, all cases were imported, followed by family clustering cases, indicating that Weihai was mainly in the stage of import and family clustering cases, prevention and control work was necessary and important to firmly block the community transmission chain.
There were more males in this group (22/38), which was consistent with the literature reported .The days between exposure and onset were 5 days, indicated that the incubation period of the disease was relatively short, the pathogenicity was strong, and the onset was rapid.
More than half (20/38) patients had chronic medical illness. The combination of chronic diseases usually indicates poor prognosis , positive treatment to chronic diseases is very important.
Seven patients had allergy history, most of them were allergy to β-lactam antibiotics. So far, there’s no relevant evidence about Covid-19 and allergy, but they are both related to our immune system. After infected by Covid-19, cytokine storm induced by virus invasion may affect the immune status. For patients with a history of allergy, it is particularly important to choose proper antibiotics when combined with bacterial infection.
The early clinical manifestations of patients with Covid-19 in this group were mainly fever, often accompanied by cough and other respiratory symptoms. Most of the patients are dry cough, and some patients have fatigue, shortness of breath and other systemic symptoms, which suggests a difference in viral tropism as compared with SARS-CoV, MERS-CoV, and seasonal influenza [17, 18].
There is no obvious severe dyspnea at the early stage of the disease. In addition, it is reported that most patients will have dyspnea in the disease progression, while a few patients have hemoptysis, diarrhea and other manifestations [12, 19]. Early recognition of signs of disease progression is important.
The most important imaging feature of patients with Covid-19 in the early stage is that HRCT shows multiple patchy ground glass shadows, some with consolidation, involved in one or both lungs, usually located under the pleura, which is very similar to the Middle East respiratory syndrome (MERS) .
As the disease progresses, the lesions may spread to both sides, showing diffuse GGO or paving stone sign, causing respiratory dysfunction, or even worse, ARDS and death. Dynamic change of image indicates the development of the disease. We listed two cases, showing dynamic imaging changes of Covid-19 CT features.
The changes of imaging were divided into different periods. Early in the disease, we found GGO distributed subpleurally; after progressive of the disease, diffuse GGO, crazy-paving pattern and consolidation distributed; to the peak stage, the involved area of the lungs slowly increased to the peak and dense consolidation became more prevalent; at absorption period, the consolidation was gradually absorbed, extensive GGO could be observed.; after dissipating, the lesion had been basically absorbed or a little fiber strip shadow could be left.
Pan  divided the dynamic changes of CT into four different periods according to the days after the initial symptoms, our results basically resembled with the study.
Most patients have normal peripheral blood leukocyte count. Both White Blood Cell Count and Neutrophil Count in group B were higher than group A, mainly associated with bacterial infection. Neutrophilia may be related to cytokine storm induced by virus invasion, but in some severe cases, leukocytopenia may occur.
Lymphocyte Count and CD4 T lymphocytes in group B were lower than group A, and below the lower normal limit. As the disease recovered, the value gradually increased. Lymphocytopenia was common in patients with Covid-19, and in some cases, severe, our finding was consistent with the results of two recent reports [12, 22].
Eosinophil Count in group B were lower than group A. Whether eosinophils are reduced or attracted to human tissues by certain factors depends on pathological sections and bone marrow pathology.
Significant difference on Platelet Count could be found in some period of the disease. From the current clinical data, most of the patients with Covid-19 are in the normal range of platelet level, and the incidence of thrombocytopenia is different. 5% of the patients with platelet count < 100 × 109 / L, 12% of the patients with platelet count < 125 × 109 / L, 36.2% of the patients with platelet count < 150 × 109 / L, which may be related to the number of cases and the proportion of light and severe patients[12, 22, 23].
There was significant difference on Total Bilirubin, ALT and AST between group A and group B. The above indexes fluctuated in different periods, considering the influence of Covid-19 or some drugs with hepatotoxicity. The nutritional status of severe patients is usually poor. Albumin in group B was lower than group A, and usually below the lower normal limit. After the treatment of albumin supplement and nutritional support, the albumin index can increase.
Acute renal impairment may occur during disease processes, related to direct effects of the virus or hypoxia. We found BUN in group B were higher than group A. LDH and A-hydroxybutyrate Dehydrogenase in group B were higher, while there were no significant difference on CK and CK-MB, indicating no obvious myocardial damage.
CRP was normal or slightly elevated and PCT was negative in general patients, consistent with other reports . The inflammatory response of most patients in the early stage of the disease is usually relatively light. With the aggravation of infection and disease, CRP and PCT could increase.
In the published descriptive articles on clinical characteristics of patients with Covid-19, prolonged PT, increased D-Dimer and fibrinogen were described, which were more common in severe patients [14, 22, 23]. Coagulation activation could have been related to sustained inflammatory response. We found PT in group B was higher than group A, while there were significant differences on APTT, fibrinogen or D-Dimer, consistent with previous studies .
This study has several limitations. First, only confirmed Covid-19 patients were included; suspected but undiagnosed cases were ruled out in the analyses. Second, 38 patients were recruited, sample size is small, especially in severe patients. It would be better to include as many patients as possible in our city, in other cities in China, and even in other countries to get a more comprehensive understanding of Covid-19. Third, grouping standard was more sensitive to identify disease progression, but the severe patients could not be stratified. No distinction was made on data of critical patients and mild severe patients. Forth, not every patient had complete results by every 4 days during the whole course, affecting the observation of the results continuity. However, the data in this study showed dynamic changes of related indexes in different periods.