Viral effects and immune‐mediated mechanisms are the two pathogeneses of severe acute respiratory syndrome‒associated coronavirus (SARS‐CoV) infection, and autoimmune responses have been found in SARS‐CoV infection. 2 One study suggested that the SARS‐CoV antigen can cross‐react with autoantibodies in autoimmune diseases. 3 Therefore, autoimmune phenomena exist in SARS subjects. In consideration of the high genetic similarity between SARS‐CoV‐2 and SARS‐CoV, it is necessary to explore the immune‐mediated mechanism of SARS‐CoV‐2 and to seek ways to prevent its spread. In this study, we present the clinical and autoimmune characteristics of COVID‐19 caused by SARS‐CoV‐2.

Since the end of 2019, we have been witnessing the emergence of the coronavirus disease 2019 (COVID‐19) outbreak and pandemic caused by a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). As of April 16, 2020, 2,079,978 cases have been confirmed worldwide, including 83,797 confirmed cases and 3,352 deaths in China, and 1,996,181 confirmed cases and 133,861 deaths in countries other than China. Within the first 2 months of the COVID‐19 outbreak, the new disease has demonstrated varying degrees of severity, with clinical characteristics having been reported in 1,099 laboratory‐confirmed subjects from 552 hospitals in 30 provinces, autonomous regions, and municipalities in China. 1 However, it has not been reported on whether autoimmune phenomena exist in COVID‐19 patients.

☑ In these cases, the prevalence of autoimmune markers, including anti‒52 kDa SSA/Ro antibody, anti‒60 kDa SSA/Ro antibody, and antinuclear antibody was 20%, 25%, and 50%, respectively, and we also found that autoimmune phenomena were present in COVID‐19 subjects.

☑ Viral effects and immune‐mediated mechanisms are the two pathogeneses of severe acute respiratory syndrome‒associated coronavirus (SARS‐CoV) infection, and autoimmune responses have been found in SARS‐CoV infection and SARS‐CoV antigen can cross‐react with autoantibodies in autoimmune diseases. In consideration of the high genetic similarity between SARS‐CoV‐2 and SARS‐CoV, it is necessary to explore the immune‐mediated mechanism of SARS‐CoV‐2 and to seek ways to prevent its spread.

Data were analyzed using the SPSS version 16.0 (SPSS, Chicago, IL). Subjects were categorized into two groups according to the COVID‐19 severity. Normally distributed variables are presented as mean ± standard deviation (SD), and comparisons were analyzed using independent‐sample t ‐test. Variables with a skewed distribution are presented as median and quartile range, and comparisons were made using the Mann‒Whitney U ‐test. Categorical variables were compared using the χ 2 test. Spearman’s two‐way test was used to assess the relationship between two quantitative variables. Two‐tailed P < 0.05 was considered statistically significant.

According to the sixth edition of Guidance for Corona Virus Disease 2019: Prevention, Control, Diagnosis and Management , issued by China’s National Health Commission, the diagnostic criteria for the clinical classification of COVID‐19 are as follows: (i) mild ―clinical symptoms are mild and no pneumonia manifestation can be found on imaging; (ii) ordinary ―symptoms such as fever and respiratory tract symptoms and pneumonia manifestations can be seen on imaging; (iii) severe ―any of the following: respiratory distress, respiratory rate (RR) ≥30 breaths/min, oxygen saturation <93% at rest, arterial partial pressure of oxygen (PaO 2 )/oxygen concentration (FIO 2 ) ≤300 mmHg (1 mmHg = 0.133 kPa), or >50% lesion progression within 24‒48 hours on pulmonary imaging; and (iv) critical ―any of the following: respiratory failure in which mechanical ventilation is required, shock occurs, or complications with another organ failure that require monitoring and treatment in the ICU. 4

From January 28, 2020 to March 2, 2020, we enrolled 21 consecutive adult subjects (13 men and 8 women), aged 42–85 years, who had laboratory‐confirmed severe and critical COVID‐19. All patients were from the intensive care unit (ICU) of the Huangshi Central Hospital, Hubei Province, China. Of these subjects, 8 (38.1%) and 13 (61.9%) were diagnosed as severe and critical cases, respectively.

The present study was approved by the ethics committee of The First Affiliated Hospital of Nanjing Medical University, Jiangsu Province, China, and the ethics committee of the Huangshi Central Hospital, Hubei Province, China. The investigation conformed to the ethical principles of the Declaration of Helsinki. Written informed consent was waived due to retrospective nature of the study and the urgent need to collect data regarding this disease.

Up to March 2, 2020, 13 of 21 patients (61.9%) were discharged from the hospital, five subjects were still in the hospital for treatment, and three patients died.

Table 5 shows the treatments for COVID‐19. Most patients (81.0%) were treated empirically with intravenous antibiotic therapy, and all received antiviral therapy with ribavirin and arbidol. Five patients (23.8%) received hormone therapy, and three (14.3%) received IVIg therapy. Thirteen (61.9%), seven (33.3%), and six (28.6%) patients were managed with noninvasive ventilation (i.e., face mask), high‐flow oxygen, and mechanical ventilation, respectively. In addition, noninvasive ventilation, high‐flow oxygen, and mechanical ventilation were initiated in more subjects with critical disease than in those with severe disease (noninvasive ventilation: 0% vs. 100%, P = 0.000; high‐flow oxygen: 62.5% vs. 15.4%, P = 0.026; mechanical ventilation: 0% vs. 46.2%, P = 0.023). Furthermore, extracorporeal membrane oxygenation (ECMO) was performed in one subject (4.8%) with critical disease. Five subjects (23.8%) used traditional Chinese medicine.

Table 4 shows the inflammatory and immunologic markers assay of the SARS‐CoV‐2 patients. Eighteen (94.7%) patients had high CRP and 17 (89.5%) had high IL‐6, but only 1 (5.6%) had elevated PCT. The prevalence of anti‒52 kDa SSA/Ro antibody, anti‒60 kDa SSA/Ro antibody, and antinuclear antibody was 20%, 25%, and 50%, respectively. The frequency of COVID‐19 antibody IgG and COVID‐19 antibody IgM was 100% and 89.5%, respectively.

Table 3 shows the laboratory measurements of patients infected with SARS‐CoV‐2 on admission. Lymphopenia, eosinopenia, thrombocytopenia, and leukopenia were present in 85.7%, 66.7%, 23.8%, and 0% of the patients, respectively. For liver function, 6 patients (28.6%) showed above‐normal ALT and 13 (61.9%) above‐normal AST levels. Nineteen patients (90.5%) had an albumin level in the lower‐than‐normal range (40 g/L). Fifteen patients (71.4%) had higher‐than‐normal fibrinogen (4.00 g/L). Blood urea nitrogen levels of nine patients (45.0%) exceeded normal (8.00 mM), and Cr level of three patients (15.0%) exceeded normal (97.0 µM). D‐dimer levels were increased in 15 patients (75.0%).

Table 2 shows the radiologic characteristics of patients on admission. All patients had abnormal chest computed tomography (CT) images. The most common characteristics of chest CT were ground‐glass opacity (100%) and bilateral patchy shadowing (76.2%). Interstitial abnormalities and local patchy shadowing were seen in 12 (57.1%) and 5 (23.8%) cases, respectively.

Fever was present in 81.0% of patients on admission, and the mean ± SD for body temperature on admission for all subjects was 38.07 ± 0.84°C. The most common symptom was cough (90.5%); none had the symptoms of nausea or vomiting, and 23.8% had diarrhea. Among the the 21 subjects, 16 (76.2%) had at least one coexisting disorder on admission.

With regard to clinical classification, 8 (38.1%) cases were severe and 13 (61.9%) patients were critical. The mean age of the subjects was 66.10 (standard deviation (SD), 13.94) years, and a total of 38.1% were women. Among these, one patient was living in Wuhan city before admission, one recently visited Wuhan city before admission, three had been in contact with Wuhan residents before admission, none had contact with the seafood market in South China, and none were medical staff.

Discussion

In this single‐center and retrospective study, we have reported on the clinical and laboratory characteristics of 8 severe and 13 critical cases of SARS‐CoV‐2 in Huangshi, Hubei Province, China. Our main findings are as follows: cough and fever were the dominant symptoms; most patients had at least one coexisting disorder on admission; the most common characteristic on chest CT was ground‐glass opacity; the most common findings on laboratory measurements were lymphocytopenia and elevated levels of CRP and IL‐6; and prevalence of anti‒52 kDa SSA/Ro antibody, anti‒60 kDa SSA/Ro antibody, and antinuclear antibody was 20%, 25%, and 50%, respectively.

One study reported on the clinical characteristics of 52 critically ill subjects with SARS‐CoV‐2 pneumonia who were admitted to the ICU of Wuhan Jin Yin‐tan Hospital (Wuhan, China) between late December 2019 and January 26, 2020.5 However, the data on critically ill subjects with SARS‐CoV‐2 infection outside of Wuhan are scarce. Due to the high mortality of critically ill subjects with SARS‐CoV‐2 pneumonia, one study focused on the clinical and laboratory information necessary for the diagnosis and treatment of COVID‐19. In the present work we found that the clinical characteristics of COVID‐19 mimicked those of other study populations,6-8 with cough, fever, lymphocytopenia, elevated levels of CRP, ground‐glass opacity, and bilateral patchy shadowing on chest CT being the dominant findings. The case fatality rate from the present study was 9.5%, substantially lower than that recently reported for 32 (61.5%) patients who died at 28 days.5 There is no clear explanation for this difference, but we believe differences in case inclusion criteria and individual differences may be a reason.

The identification of the potential risk factors of D‐dimer >1 µg/L and high IL‐6 level for identifying subjects with a poor prognosis has been described in a retrospective, multicenter cohort study conducted at Jinyintan Hospital and Wuhan Pulmonary Hospital (Wuhan, China).9 In agreement with that study, we found that D‐dimer and IL‐6 levels were higher than the reference range, and that these markers may play diagnostic and therapeutic roles in combating COVID‐19.

Another study was conducted to explore the clinical characteristics and allergy status of subjects with SARS‐CoV‐2. The results suggested eosinopenia and lymphopenia may be indicators for a COVID‐19 diagnosis, but that allergic diseases, asthma, and COPD are not risk factors for SARS‐CoV‐2 infection.10 To date, however, the relationship between immune status and autoimmune phenomena with SARS‐CoV‐2 infection has not been reported. Herein we found that prevalence of anti‒52 kDa SSA/Ro antibody, anti‒60 kDa SSA/Ro antibody, and antinuclear antibody was 20%, 25%, and 50%, respectively. Therefore, we conclude that autoimmune phenomena exist in COVID‐19 subjects, which provides a rationale for a strategy of prevention of dysfunction of immune and optimal immunosuppressive therapy in the future. To the best of our knowledge, this is the first report to describe COVID‐19 patients with features of autoreactivity.

Our study has several limitations. The clinical and laboratory data were from only 21 severe and critical COVID‐19 cases. Thus, larger samples and a multicenter studies will needed to verify our initial observations. Furthermore, because this study was retrospective in nature, prognostic data were unavailable. In addition, several cases had incomplete data on laboratory testing due to the urgent timeline for document extraction.