COVID-19 is a major health concern since its first occurrence in 2019. COVID-19 is caused by the SARS-CoV-2 virus, and can be devastating, especially for the elderly.  

Pathogenesis of COVID-19: 

Based on past studies with SARS-CoV, the inhaled SARS-CoV-2 virus most likely binds to epithelial cells in the nasal cavity and starts replicating. Hence, nasal swabs can detect the presence of SARS-CoV-2 virus. The pathological features of SARS and COVID-19 is diffuse alveolar damage with fibrin rich hyaline membranes and a few multinucleated giant cells. The aberrant wound healing may lead to more severe scarring and fibrosis compared to other forms of acute respiratory distress syndrome (ARDS). Elderly are particularly at risk due to their diminished immune response, reduced ability to repair the damaged epithelium, and reduced mucociliary clearance, which may allow the virus to spread more readily within the lungs. 

Symptoms of COVID-19: 

Most common are fever, cough, tiredness, loss of taste or smell. Less common are sore throat, headache, aches and pains, diarrhoea, skin rash or discolouration of fingers or toes, red or irritated eyes. Serious ones are difficulty breathing or shortness of breath, loss of speech or mobility, confusion or chest pain. 

TCM views on COVID-19: 

COVID-19, like most infectious diseases, is categorised broadly as febrile disease in TCM. This is because the main clinical response for febrile disease is inflammatory, which is the same as the pathophysiology of COVID-19.  

There are two types of febrile disease: 

  1. Warm-heat (温热): This type demonstrates as alterative inflammation, which is characterised by degeneration and necrosis of tissue cells. 
  1. Damp-heat (湿热): This type demonstrates as exudative inflammation, which is characterised by formation of exudate and edema, often developed into fibrosis. 

Comparing the characteristics of febrile disease with the pathological features of COVID-19, TCM classifies COVID-19 as the Damp-heat type. 

Damp-heat can either affect the pancreas-stomach system or the liver-bile system. When the pancreas (spleen) is deficient, dampness can easily stagnate and affect the pancreas (spleen) function. Symptoms of pancreas (spleen) deficiency are usually exhibited as diarrhoea and decrease in appetite. TCM believes that the interstitium (three warmer) is the passageway for fluid and participates in metabolism for body fluids. Hence any disruption to the function of the interstitium (three warmer) can cause dampness to accumulate or stagnate, which turns to stagnant-heat. This can display as symptoms like cough and chest pain. TCM also believes that the root cause for fatigue is liver, hence liver deficiency often shows tiredness. Liver-bile meridians circulate the head and eye area, hence any disturbance to the flow of the meridians results in symptoms such as headaches and red or irritated eyes. In all, the symptoms of Damp-heat indicate that COVID-19 should be treated as Damp-heat type. 

COVID-19 is also related to Tai Yin and Shao Yang from the perspective of TCM. Tai Yin governs the lung and pancreas (spleen) meridians and correlates with Tai Yang which is the first line of defence in our body. As Tai Yin governs the lungs, diseases of Tai Yin display respiratory symptoms. Shao Yang governs the interstitium (three warmer) and the bile meridians and is the pivot point between the exterior stage (within the dermal or subcutaneous layer) and interior stage (enter the organ layer) of our body system. When disease is said to be at Shao Yang, it means that the disease if treated properly can be cured by expelling the pathogen or can worsen if left untreated and damage the organs. Main symptoms for diseases related to Shao Yang involve bitterness in mouth, sore throat, and dizziness. Thus, both Tai Yin and Shao Yang are considered for treatment of COVID-19 since COVID-19 belongs to the Damp-heat type of febrile diseases and Tai Yin and Shao Yang directs at Damp-heat according to the theory of five organs and six viscera and the theory of meridian and collateral. 

TCM Treatment on COVID-19: 

For TCM, we recommend preventive treatment before onset of disease (未病先防). Therefore, Chai Ling Tang (柴苓汤) is prescribed to prevent COVID-19 as it targets Tai Yin and Shao Yang. This is also suitable for patients who are at the early stages of COVID-19 or recovering from COVID-19.  

Chai Ling Tang is made up of two classic prescriptions, namely, Xiao Chai Hu Tang (小柴胡汤) and Wu Ling San (五苓散). Xiao Chai Hu Tang targets Shao Yang by clearing exudate in the interstitium (three warmer) and regulating water metabolism. Furthermore, Xiao Chai Hu Tang expels pathogens from Shao Yang out of the body system, and dispel heat which will ease the inflammatory response. On the other hand, Wu Ling San targets Tai Yin by replenishing pancreas (spleen) to induce diuresis and excrete dampness. This changes the body environment to one that is not suitable for SARS-CoV-2 virus to thrive in and propagate, which in turn prevents SARS-CoV-2 virus from infecting our body system. Overall, Chai Ling Tang helps to boost immunity and is used to treat febrile disease with symptoms such as fever, fatigue, sore throat, diarrhoea and cough, like the early phase of COVID-19 .