This article is excerpted from the Emergency Infectious Diseases Group of the Emergency Physicians Branch of the Chinese Medical Association. Clinical Practice Guidelines for the Diagnosis and Treatment of Common Cold in Adults (2023) [J] International Journal of Respiratory Sciences, 2023,43 (3): 6-31. DOI: 10.3760/cma.j. cn131368-20221221-01138

  Clinical Practice Guidelines for Diagnosis and Treatment of Adult Common Cold (2023) 

The common cold (commonly known as the cold) is a disease limited to the upper respiratory tract, characterized by symptoms such as nasal congestion, runny nose, sore throat, and cough. It can be caused by different types of viral infections and is a self limiting disease, with symptoms typically lasting less than 10 days [1-2]. Imaging studies on the upper respiratory tract and paranasal sinuses of adult cold patients have shown [3-4] that cold has acute nasal and paranasal sinusitis characteristics. At least one or more paranasal sinuses (ethmoid, maxillary, frontal or sphenoid) in the patient experience swelling and inflammatory exudation, accompanied by increased nasal airflow resistance, but there are no imaging abnormalities in the lungs.
The impact of colds on human society should not be underestimated. In the 1970s, community surveys in the United States showed that young adults aged 30-50 may experience 2-3 cold-like symptoms per year, and the younger the age, the more colds they have. The direct annual cost of controlling colds in the United States is nearly 6 billion US dollars (approximately 42 billion Chinese yuan) [6-7]. According to a Swedish survey, the per capita clinical cost for patients with acute sinusitis is 1102 euros (approximately 8000 RMB) [8], with 5.1 days of absenteeism and a per capita loss of approximately 653 euros, resulting in an overall loss of work, equivalent to 2.7 billion euros [9]. It has been reported in the Beijing and Shanghai regions of China that the average medication cost for a cold in a regular outpatient clinic is about 91.07 to 97.67 yuan. The maximum amount of a single prescription can reach 300.4 yuan and 201.7 yuan in Beijing and Shanghai, respectively [10-11].
Although there have been multiple expert consensuses related to colds in China, such as the 2012 Expert Consensus on Standardized Diagnosis and Treatment of Common Cold [12], the 2020 Guidelines for Grassroots Rational Use of Drugs for Acute Upper Respiratory Tract Infections [13], and the 2021 Expert Consensus on Emergency Diagnosis and Treatment of Acute Respiratory Virus Infections in Adults [14], there is a lack of adult cold diagnosis and treatment guidelines based on good evidence and strict adherence to international guidelines. In recent years, new evidence-based medical evidence has been accumulated in the diagnosis and treatment of colds and acute paranasal sinusitis. Especially since the global novel coronavirus disease 2019 (COVID-19) pandemic, human beings have a more in-depth understanding of the diagnosis and treatment of respiratory system virus infection. It is necessary to reflect these new evidence in the new guidance document in a timely manner to provide reference for clinical diagnosis and treatment of patients.

Question NQ1: What are the common causes of the common cold?
Recommendation 1: Common pathogenic factors of colds include rhinovirus (RV), coronavirus, influenza, and parainfluenza viruses. Respiratory syncytial virus (RSV), adenovirus, human metapneumovirus (hMPV), enterovirus, Mycoplasma pneumoniae, and Chlamydia pneumoniae infections can also cause cold like symptoms (high-quality evidence).
Summary of evidence: Human understanding of the causes of colds mainly stems from tracking studies based on families and communities in the 20th century [1]. In recent years, with the advancement of microbial detection technology, especially the clinical application of PCR, it has been revealed that various pathogenic microorganisms can cause cold-like symptoms, including RV, human coronavirus (HCoV), parainfluenza virus (PIV), RSV, adenovirus, enterovirus, hMPV, human Boca virus, Mycoplasma pneumoniae, and Chlamydia pneumoniae [5,20-22]. Among them, RV accounts for about 50%, while HCoV, influenza virus, and PIV account for about 1/4 to 1/5. It is not uncommon to detect two or more pathogenic bacteria in the same case [22]. RV is divided into three types: RV-A, RV-B, and RV-C, with at least 169 subtypes. RV-A and RV-C infections are not only common but also have severe clinical symptoms, while RV-B is usually an asymptomatic carrier [23]; RV-C is more common in children and is often isolated in infants and young children under 2 years old [24], while RV-A is more common in adults [25].
Other evidence: Upper respiratory secretions from cold patients can infect others, suggesting that colds are an infectious disease [26-27]. RV stimulation can also induce healthy volunteers to exhibit typical cold like symptoms [28-29]. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Omicron, which is widely prevalent both domestically and internationally in 2022（ ο) And Delta（ δ) The mutant strain mainly infects the upper respiratory tract with less involvement in the lower respiratory tract [30-31], and has the characteristics of a cold virus.
Note: Cold is defined as a condition limited to the upper respiratory tract, mainly caused by viral infections, and other novel respiratory viruses such as SARS-CoV-2 ο and δ Mutant strains can also become the cause of colds.
Question NQ2: Do we need to undergo further routine testing, including pathogen testing, for the common cold in adults?
Recommendation 2: For usually healthy cold patients, diagnosis can be based on detailed medical history and physical examination, and imaging and laboratory tests are not recommended. However, for patients with combined fever above 38 ℃, shortness of breath, hemoptysis, suspected pneumonia, heart failure, immunodeficiency, and inhalation poisoning, it is recommended to undergo corresponding imaging and laboratory examinations as soon as possible (high-quality evidence).
Recommendation 3: If the symptoms of a cold persist for 5 days but worsen, or if the symptoms persist for more than 10 days, and the following situations occur: thick purulent nasal mucus and sputum, increased pain in the paranasal sinuses (usually unilateral) and pharynx, fever ≥ 38 ℃, increased C-reactive protein (CRP) and procalcitonin (PCT), increased erythrocyte sedimentation rate (ESR), difficulty breathing, and/or hemodynamic instability, complications should be considered, such as secondary acute bacterial rhinosinusitis (ABRS), cardiovascular emergencies, etc. Symptomatic or structural lung diseases, such as chronic obstructive pulmonary disease (COPD), acute attacks such as bronchiectasis and interstitial pneumonia, are recommended to undergo corresponding imaging and laboratory tests as soon as possible (high-quality evidence). Summary of evidence: Cold symptoms usually peak in 2-3 days and gradually improve after 5 days, with a duration typically less than 10 days [1,32-34], as shown in Figure 1. A cold can trigger acute attacks of various diseases and worsen underlying diseases. If the symptoms of a cold do not improve after 5 days, but instead worsen, or if the symptoms last for more than 10 days but less than 12 weeks, the 2020 European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) defined this condition as acute viral infection induced sinusitis. If the latter presents three or more conditions listed below, such as fever>38 ℃, worsening after symptom relief, local symptoms and pain in unilateral sinusitis, as well as increased CRP and ESR, ABRS should be considered. Figure 2 [2]. Due to the susceptibility of respiratory virus infections to co infection with respiratory bacteria [35-37], pathogenic tests should be conducted for high-risk patients with community-acquired pneumonia (CAP) or acute exacerbation of structural lung disease due to colds (Table 3), as well as patients who are considered to have ABRS as drug-resistant bacterial infections (such as those who have used antibiotics within 90 days or have a possibility of infection related to medical care institutions) [38-39].
Other evidence: The recommendations in this section are based on relevant guidelines from EPOS and the German Respiratory Society [2,40]. PCT levels are commonly used to distinguish between viral and bacterial infections, with diagnostic efficacy higher than CRP [41-43]. However, in recent years, it has been observed that even if the PCT is not high, bacterial infections cannot be ruled out, especially atypical pathogens such as Mycoplasma pneumoniae and Chlamydia pneumoniae [44]. For patients whose symptoms tend to worsen, pathogenic tests including bacterial culture should be conducted.
Note: For diseases that usually self heal, such as colds, it is feasible to avoid early examinations including imaging and etiology. However, for patients who have worsened underlying diseases or developed ABRS due to colds, further examinations should be conducted as soon as possible.

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