Abstract
OBJECTIVE:
To characterize the tongue and pulse manifestations in asymptomatic coronavirus disease 2019 (COVID-19) cases in Shanghai.
METHODS:
We conducted a clinical study of 668 patients with asymptomatic infections in which we analyzed the tongue and pulse features in the Shanghai New International Expo Center mobile cabin hospital. The medical records of the patients, including tongue color, tongue coating, and pulse manifestations, were reviewed by healthcare workers.
RESULTS:
In total, 668 COVID-19 cases were included in the study. Patient age ranged from 5 to 96 years, with a median of 44.0 (IQR 33.0-53.0) years. Among the patients, 6.14% had comorbidities. The most common comorbid condition was diabetes (1.65%), followed by hypertension (0.89%), coronary heart disease (0.89%), thrombotic diseases (0.89%), congestive heart failure (0.60%), and stroke (0.45%). Pink-red (75.4%) was the most common tongue color, followed by red (23.4%) and pale red (1.2%). Tongue coating color and thickness were classified as white fur (9.28%), thin and yellow fur (48.65%), white greasy fur (8.98%), yellow greasy fur (24.70%), and less coating (8.39%). In addition, a large number of patients (n = 300, 44.91%) presented superficial and rapid pulses, and 250 patients (37.4%) exhibited a slippery pulse.
CONCLUSION:
Our preliminary results showed that wind, heat, and dampness were the main etiologies of the severe acute respiratory syndrome coronavirus 2 Omicron (B.1.1.529) variant infection in traditional Chinese medicine. Furthermore, the main symptoms of the disease may be wind-heat invading the lung syndrome or damp-heat with the exuberance of virulence syndrome, which is of most significance in COVID-19 treatment.
Keywords: SARS-CoV-2 Omicron, asymptomatic infections, tongue feature, pulse feature
1. INTRODUCTION
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron (B.1.1.529) variant was first identified in South Africa on November 9, 2021 and reported to the World Health Organization (WHO) on November 24, 2021.1 Given its numerous mutations, particularly in the spike protein, there have been concerns about increased transmissibility and higher binding affinity; the virus spread rapidly over 100 countries, as of February 19, 2022.2,⇓-4 These potential concerns have shown a correlation with the recent steep increase in the number of cases.5 As of May 6, 2022, over 518 million cases have occurred worldwide, with over 6 million deaths.6 According to the newest National Health Commission of China report, the Omicron variant was identified in China on December 9, 2021; subsequently, it become the dominant variant in China.2 Omicron has a higher “asymptomatic carriage” rate than the previous SARS-CoV-2 variants.7 Although asymptomatic infections have no obvious clinical features, the patients should be sent into isolation for observation due to their contagiousness.8 Therefore, it is a tremendous challenge to prevent and control this specific type of case globally, and it deserves more attention worldwide.
Tongue and pulse diagnoses play an important role in clinical diagnosis and treatment in Traditional Chinese Medicine (TCM).9 Tongue and pulse diagnoses are comprehensive diagnostic methods based on the body’s overall state, are suitable for comprehensive evaluation of the body’s functional state, and have become an important objective basis for health status evaluation and syndrome diagnosis. Researches based on tongue and pulse manifestations in the coronavirus disease 2019 (COVID-19) population have shown that the tongue and pulse had unique characteristics.10,⇓-12 Despite the progress in the current research on COVID-19, few studies have reported the symptom characteristics of the SARS-CoV-2 Omicron variant in China. This is the first study on COVID-19 syndrome differentiation strategy providing a methodological inspiration for future study and a reference for the application of the diagnostic criteria of COVID-19.
2. MATERIALS AND METHODS
2.1. Study design and participants
This single-center retrospective study was performed at the Shanghai New International Expo Center Cabin Hospital. This medical institution, the largest quarantine venue in Shanghai, had 15 000 beds and treated more than 40 000 hospitalized patients with COVID-19 from 1 April to 15 June, 2022. All cases were confirmed by reverse transcription polymerase chain reaction (RT-PCR), the gold-standard test. All asymptomatic inpatients who tested positive for SARS-CoV-2 from April 1 to April 5, 2022, were enrolled. Exclusion criteria were (a) no positive swab during the hospital stay, (b) at least one symptom, and (c) admitted with mild to severe/critical COVID-19.
The study was approved by the Longhua Hospital, Shanghai University of Traditional Chinese Medicine Ethical Review Authority (DNR 2020-02150) and registered with the Chinese Clinical Trial Registry (ChiCTR2200060472).
2.2. Procedures
Totally 1223 samples were selected from our ward at the Shanghai New International Expo Center cabin hospital. Finally, we identified symptomatic and asymptomatic patients based on Diagnosis and treatment plan for COVID-19 (trial version 9).13 Of these, 322 patients with mild COVID-19 and 30 with severe COVID-19 were excluded, and 193 patients with missing data of sex, age, tongue, and pulse features were excluded, leaving 668 asymptomatic inpatients for the final analysis. A flowchart of the process is shown in Figure 1.
Figure 1. Flowchart.
COVID-19: coronavirus disease 2019.
Data on the epidemiological characteristics, drugs and therapies, and chronic diseases of inpatients were collected. We extracted the TCM-based tongue and pulse conditions. The latest guidelines from Chinese professors and academicians indicated that asymptomatic patients with COVID-19 should be treated in isolated hospitals with effective isolation and protection. Close monitoring of vital signs and symptomatic support are necessary. Early TCM treatment with herbal medicines can prevent progression to severe or critical diseases. All data were entered into a computerized database, and a manual review was performed by different researchers for further analyses. The data were extracted to help us to detect patterns of TCM symptoms and further treatments for COVID-19.
2.3. Data normalization
Data were collected, including age, sex, basic disease, vaccine, race, disease severity, symptoms, and tongue and pulse features. Furthermore, we extracted the data and converted the entries into a “TCM syndrome classification table of patients infected with the Omicron variant” form, which were developed according to textbooks of “diagnostics of Traditional Chinese Medicine” and “Chinese internal medicine.” Finally, we identified four symptom categories. Using similar manual processing steps, we obtained 11 distinct terms for the tongue-related manifestations. Furthermore, we analyzed the tongue and pulse manifestations by comparing the asymptomatic patients with COVID-19 Omicron variant infections in Shanghai in 2022 (2022 Shanghai group), the 983 reference cases with COVID-19 infection in Wuhan from January 26, 2020 to March 2, 202014 (2020 Wuhan group), and 50 cases in Shanghai before March 202015 (2020 Shanghai group).
2.4. Statistical and data analyses
Descriptive and continuous variables were expressed as mean SD or median (IQR) and subjected to the Mann-Whitney U test. Categorical variables were expressed numerically as percentages and compared via χ2 test or Fisher’s exact test between the different groups. A two-sided α value of less than 0.05 was considered statistically significant. All calculations and regression analyses were performed using SPSS version 25 (IBM Corp., Armonk, NY, USA).
3. RESULTS
3.1. Clinical characteristics of 668 asymptomatic patients with COVID-19
The demographic and epidemiological data of the 668 patients with confirmed Omicron variant infections are summarized in Table 1. The median age of the patients was 44.0 (IQR 33.0-53.0) years, and 50.6% of them were men (Figure 2). Among the patients, 6.14% had comorbidities. The most common comorbid condition was diabetes (1.65%), followed by hypertension (0.89%), coronary heart disease (0.89%), thrombotic diseases (0.89%), congestive heart failure (0.60%), and stroke (0.45%).
Table 1.
Characteristics of asymptomatic COVID-19 cases [n (%)]
| Demographics and clinical characteristics | Total
(n = 668) |
|
|---|---|---|
| Sex | Male | 338 (50.6) |
| Female | 330 (49.4) | |
| Age (years) | 44 (33-53) | |
| Any comorbidity | 41 (6.14) | |
| Diabetes | 11 (1.65) | |
| Hypertension | 6 (0.89) | |
| Coronary heart disease | 6 (0.89) | |
| Thrombotic diseases | 6 (0.89) | |
| Congestive heart failure | 4 (0.60) | |
| Stroke | 3 (0.45) | |
Note: COVID-19: coronavirus disease 2019.
Figure 2. Age distribution characteristics of patients with SARS-CoV-2 Omicron variant .
SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.
3.2. Tongue and pulse characteristics
Tongue inspection refers to the visual examination of tongue color, fur color, and fur thickness. Among the 668 symptomatic patients with COVID-19, pink-red (75.4%) was the most common tongue color, followed by red (23.4%) and pale red (1.2%). Tongue coating color and thickness were classified as white fur (9.28%), thin and yellow fur (48.65%), white greasy fur (8.98%), yellow greasy fur (24.70%), and less coating (8.39%) (Table 2). Typical tongue feature of asymptomatic COVID-19 cases were shown in Figure 3.
Table 2.
Tongue feature of asymptomatic COVID-19 cases [n (%)]
| Tongue feature | Total
(n = 668) |
|
|---|---|---|
| Tongue color | Pure red | 504 (75.4) |
| Red | 156 (23.4) | |
| Pale | 8 (1.2) | |
| Fur characteristics | While | 62 (9.3) |
| Thin yellow | 325 (48.7) | |
| White greasy | 60 (9.0) | |
| Yellow greasy | 165 (24.7) | |
| Less coating | 56 (8.4) | |
Note: COVID-19: coronavirus disease 2019.
Figure 3. typical tongue feature of asymptomatic COVID-19 cases.
A: thin yellow fur; B: yellow greasy fur; C: less coating; D: white greasy fur; E: white fur. COVID-19: coronavirus disease 2019.
Furthermore, we evaluated 11 tongue characteristics through a combination of tongue coating and color features. We observed a higher rate of pink-red tongue color with thin and yellow fur (35.48%), followed by pink-red tongue color with yellow greasy fur (19.46%), and red tongue color with thin and yellow fur (13.17%). Detailed characteristics of the tongue characteristics are presented in Table 3.
Table 3.
Characteristics of tongue conditions by a combination of tongue coating and tongue color features [n (%)]
| Tongue feature | Total
(n = 668) |
|---|---|
| Red tongue, thin yellow fur | 88 (13.17) |
| Pure red tongue, thin yellow fur | 237 (35.48) |
| Pure red tongue, yellow greasy fur | 130 (19.46) |
| Red tongue, yellow greasy fur | 35 (5.24) |
| Red tongue, white fur | 13 (1.95) |
| Red tongue, white greasy fur | 17 (2.54) |
| Pure red tongue, white greasy fur | 43 (6.44) |
| Pure red tongue, white greasy fur | 49 (7.34) |
| Red tongue, less coating | 3 (0.45) |
| Pure red tongue, less coating | 45 (6.74) |
| Pale tongue, less coating | 8 (1.19) |
The features of the pulse conditions in patients with COVID-19 with asymptomatic infections are listed in Table 4. Specifically, a high number of cases (n = 300, 44.91%) manifested as superficial and rapid pulses, which usually indicates wind heat from the pathological perspective of TCM. A total of 250 patients (37.43%) exhibited a slippery pulse, as slippery alone or rapid and slippery pulses. According to the TCM theory, slippery pulse is a potential manifestation of pathogenic dampness.
Table 4.
Pulse feature in asymptomatic COVID-19 cases [n (%)]
| Pulse feature | Total
(n = 668) |
|---|---|
| Superficial rapid | 300 (44.91) |
| Thready rapid | 67 (10.03) |
| Deep thready | 51 (7.63) |
| Slippery (single) | 152 (22.76) |
| Slippery rapid | 98 (14.67) |
Note: COVID-19: coronavirus disease 2019.
3.3. Distribution and comparison of syndromes in the asymptomatic infection period of COVID-19
Based on a comprehensive summary by three chief traditional Chinese physicians, SARS-CoV-2 Omicron variant infections can potentially be differentiated into four syndromes: wind-heat invading the lung syndrome (48.65%), damp-heat with exuberance of virulence syndrome (24.70%), pathogenic dampness invading the lung syndrome (18.27%), and Yin deficiency due to lung heat syndrome (8.38%).
The diagnostic basis for wind-heat invading the lung syndrome is a pink-red tongue with thin and yellow fur or a red tongue with thin and yellow fur, and a superficial and rapid pulse; damp-heat with exuberance of virulence syndrome, a pink-red tongue with yellow greasy fur, red tongue with yellow greasy fur, or slippery pulse or rapid and slippery pulse; pathogenic dampness invading the lung syndrome, a pink-red tongue with white fur, red tongue with white fur, pink-red tongue with white greasy fur, or red tongue with white greasy fur, and a slippery pulse; Yin deficiency due to lung heat syndrome, a pink-red tongue with less coating, red tongue with less coating, pale tongue with less coating, or a thready rapid pulse, or a deep and thready pulse.
3.4. Comparison of tongue and pulse manifestations between the asymptomatic patients infected with the Omicron variant in Shanghai in 2022 and patients with COVID-19 in Wuhan and Shanghai from 2019-2020
Tongue and pulse manifestations were significantly different between the 2022 Shanghai group and the other two groups. The chi-square test showed that 75.4% (504) patients exhibited a pink-red tongue in the Shanghai 2022 group, which was significantly higher than the proportions in the Wuhan 2020 (53, 5.4%) and Shanghai 2020 groups (23, 46%) (P < 0.001). The proportion of patients with a red tongue was significantly higher in the Shanghai 2022 group than that in the Wuhan 2020 group (23.4% vs 43%, P < 0.001). However, 1.2% of patients in the Shanghai 2022 group exhibited a pale tongue, less than those in the Wuhan 2020 (16.6%) and Shanghai 2020 groups (16%) (P < 0.001) (Table 5).
Table 5.
Tongue and pulse features in asymptomatic SARS-CoV-2 Omicron variant patients in 2022 and Wuhan variant patients in 2020 [n (%)]
| Tongue and pulse feature | Shanghai 2022 group
(n = 668) |
Wuhan 2020 group
(n = 983) |
Shanghai 2020 group
(n = 50) |
|
|---|---|---|---|---|
| Tongue color | Pure red | 504 (75.4) | 53 (5.4)a | 23 (46.0)a |
| Red | 156 (23.4) | 423 (43.0)a | 18 (36.0)b | |
| Pale | 8 (1.2) | 163 (16.6)a | 8 (16.0)a | |
| Fur characteristics | Thin yellow | 325 (48.7) | 79 (8.0)a | - |
| White | 122 (18.3) | 348 (35.4)a | 37 (74.0)a | |
| Greasy | 225 (33.7) | 430 (43.7)a | 34 (68.0)a | |
| Slippery plus | 250 (37.4) | 314 (31.9)b | 22 (44.0) | |
Notes: P values were calculated via χ2 test, or Fisher’s exact test as appropriate. P values were used to compare the Shanghai 2022 group and Wuhan 2020 group or Shanghai 2020 group. SARS-CoV-2: severe acute respiratory syndrome coronavirus 2. aP < 0.01, bP < 0.01. -: no data.
On analyzing the tongue coatings in the three patient groups, 325 (48.7%) patients in the Shanghai 2022 and 79 (8.0%) patients in the Wuhan 2020 groups (P < 0.001) exhibited thin and yellow fur. The proportions of patients with white fur and greasy fur were 18.3% and 33.7% in the Shanghai 2022 group, less than 35.4% and 43.7% in the Wuhan 2020 group, and 74% and 68% in the Shanghai 2020 group, respectively (P < 0.001) (Table 5).
Further, the proportions of pulse conditions were comparable between the Shanghai 2022 group and the Wuhan 2020 group or Shanghai 2020 group. The proportion of patients with slippery pulse was significantly higher in the Shanghai 2022 group than that in the Wuhan 2020 group (37.4% vs 31.9%, P < 0.05); however, there was no significant difference between the Shanghai 2022 and Shanghai 2020 groups (P > 0.05) (Table 5).
4. DISCUSSION
Outbreaks of COVID-19 caused by the SARS-CoV-2 Omicron variant have added fuel to the close to 2-years' apparently endless flame of the global COVID-19 pandemic.16 The strict and comprehensive pandemic control strategies in Shanghai aimed to control the spread of the Omicron variant in China’s economic capital.17,18 To date, few studies on the Omicron variant have been carried out to better define the threat of the variant.
Historically, TCM has been effective for the treatment of infectious diseases. In the 3000 years of Chinese history, TCM has served as the conventional treatment regime for epidemics and infections.19 During 2019-2021, many TCM-based treatments have been rapidly developed and used for the management of COVID-19.20,⇓,⇓,⇓,⇓-25 Lianhua Qingwen, in combination with conventional therapy, has been recommended by the Evidence-Based Medicine Chapter of China International Exchange and Promotive Association for Medical and Health Care for the treatment of patients with mild or moderate COVID-19,26 and some studies showed that conjunction therapy is beneficial for patients with COVID-19.27 Another study evaluating Shenhuang Granule in 111 confirmed cases of COVID-1928 showed that a combination of standard treatment and Shenhuang granule (SHG) led to a lower overall mortality than that in the control group (38.6% vs 75.9%, P < 0.01). In those with severe disease, the mortality rate was reduced by 50.5% after SHG administration. The mechanisms of TCM in treating COVID-19 mainly include inhibiting the binding of the virus with the receptor, suppressing cytokine storms.29
Based on prior therapeutic experience and the characteristics of patients infected with the SARS-CoV-2 Omicron variant, we opine that COVID-19 belongs to the category of “epidemic febrile disease” (Wen Bing) in TCM, and the main nature of the disease is wind-heat and dampness-heat. Omicron BA.2 is evolving towards a less virulent form, with a higher rate of asymptomatic carriers and mild COVID-19 with “extremely mild” clinical symptoms including fever or no fever, dry cough, fatigue, vomiting, loose stools, etc.30 An examination of the patterns of TCM symptom phenotypes is crucial for disease diagnosis and treatment by the TCM practitioner.31 Therefore, TCM tongue and pulse features were employed to elucidate the TCM symptoms of asymptomatic infections in detail, which will help in early control, prevention, and treatment of the disease. In the analysis of 983 cases with light and general COVID-19 diagnosed in 10 hospitals in Wuhan from January 26 to March 2, 2020,14 the main pulse and tongue features were red tongue, yellow greasy fur, and slippery pulse. In a clinical trial conducted by Lu et al,15 the general features and distribution of Chinese medical syndromes in 50 novel coronavirus-infected patients from Shanghai Public Health Clinical before April, 2020, the main tongue and pulse features were light-red tongue or red tongue, greasy coat, and slippery pulse. In our study, compared with the Wuhan variant infection in 2020, the Omicron variant infection had a higher rate of pure-red tongue, thin yellow fur, and superficial rapid pulse. However, no particular difference was observed in the rates of slippery pulse and yellow greasy fur between the two variants. Based on the TCM theory, thin yellow fur indicates wind-heat, and yellow greasy fur is usually associated with dampness-heat.32 The pulse condition of the wind-heat syndrome is superficial and rapid and that of dampness-heat syndrome is slippery.
Our study indicates that wind, heat, and dampness are the main etiologies of TCM, with four different syndromes including wind-heat invading the lung syndrome, damp-heat with the exuberance of virulence syndrome, pathogenic dampness invading the lung syndrome, and yin deficiency due to lung heat syndrome.
From a therapeutic perspective, based on clinical symptoms, TCM-based treatment should be conducted forward.33 Medications to dispel the wind and heat, clear the heat, and draining the dampness may inhibit the progression of COVID-19 in a timely and effective manner. After the patients test negative for the SARS-CoV-2 nucleic acid, they should receive traditional Chinese therapy for rehabilitation to further reduce residual problems and relapses.
Our study had several limitations. First, pulse and tongue conditions were reported by clinicians, whose diagnoses were bound to be subjective. Hence, modern medical devices are required to validate the reliability of the diagnosis. Second, the sample size was relatively small. Therefore, further studies with larger sample sizes, including those with mild, moderate, and severe diseases, are required to determine the relationship between tongue manifestations and the disease.
In conclusion, we described the tongue and pulse features of 668 COVID-19 asymptomatic carriers in Shanghai. Our results reconfirmed some common tongue and pulse conditions, i.e., thin yellow fur, greasy fur, superficial rapid pulses, and slippery pulses. Furthermore, we suggest that wind-heat syndrome and dampness-heat syndrome are the main symptoms. Therefore, this study will guide future treatment.
Contributor Information
Shuang ZHOU, Email: fangbji@163.com.
Bangjiang FANG, Email: zhoushuang8008@163.com.
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