I heard that many "big white lungs" have appeared. Do they all need to undergo chest CT scans if they are infected with the new coronavirus?

We are currently at the peak of the novel coronavirus infection. Many people have experienced fever, cough, sore throat and other discomforts after being infected with the novel coronavirus. After a period of time, the symptoms have not improved, and they have begun to worry about whether they have "pneumonia". Recently, there has been news that "the patient's CT chest film showed white lungs", which has made everyone more anxious.

Chest CT can confirm pneumonia. So, after being infected with the new coronavirus, is it necessary for everyone to do a chest CT?

01

COVID-19 infection and pneumonia

Currently, cases of infection with the Omicron strain of the new coronavirus have become the main prevalent strain. Vaccinated Omicron-infected people mainly suffer from mild symptoms, and the clinical symptoms mainly include upper respiratory tract infection symptoms such as fever, dry throat, sore throat, nasal congestion, and runny nose.

However, for some high-risk patients with COVID-19, as the disease progresses, the virus continues to spread from the upper respiratory tract to the lower respiratory tract, and the virus enters the lungs, causing secondary lung infection and leading to viral pneumonia. Some patients will also develop secondary bacterial pneumonia.

If the patient has a weak constitution, poor immunity, or inhales a large amount of virus with high density, the virus can directly cause pneumonia.

That is to say, for patients generally infected with the new coronavirus, the lesions are limited to the upper respiratory tract and the lungs are not infected; however, some patients, especially high-risk patients, are at risk of pneumonia.

02

Mild illness, even with pneumonia

The performance is not terrible

According to the clinical classification of pneumonia in the "Diagnosis and Treatment Plan for Novel Coronavirus Pneumonia (Trial Ninth Edition)", we can analyze the specific conditions of COVID-19 patients:

Mild patients : may present with low fever, mild fatigue, olfactory and taste disorders, etc. The clinical symptoms are mild, and no pneumonia is found in imaging. Therefore, patients with mild symptoms do not need chest CT.

Common type patients : have clinical manifestations such as fever, dry cough, fatigue, etc., and pneumonia can be seen in imaging.

According to the "Reference Plan for the Diagnosis and Treatment of COVID-19 in the Department of Respiratory and Critical Care Medicine of Peking Union Medical College Hospital (December 2022 Edition)", some mild patients may also have pneumonia symptoms, but if there are no other severe symptoms or risk factors, it does not necessarily indicate a poor prognosis. The presence of imaging manifestations of pneumonia without other critical factors does not constitute an indication for hospitalization.

The plan also recommends that routine CT examinations are not recommended for people without risk factors (such as previously healthy young people), but close monitoring of oxygen levels is recommended.

03

The following groups are at high risk

CT scan should be done

Our focus should be on high-risk groups with severe/critical illness .

Specifically, COVID-19 is more likely to occur in the following high-risk groups:

Elderly people over 60 years old;

Those with underlying diseases such as cardiovascular and cerebrovascular diseases (including hypertension), chronic lung diseases, diabetes, chronic liver and kidney diseases, tumors, etc.

Immune deficiency (such as AIDS patients, long-term use of corticosteroids or other immunosuppressive drugs leading to immunodeficiency);

Obesity (BMI ≥ 30);

Women in late pregnancy and the perinatal period and heavy smokers.

04

What is the significance of chest CT?

1. Early diagnosis

Chest CT examination combined with clinical and laboratory tests can help to diagnose pneumonia at an early stage. Chest CT examination is particularly important for a small number of patients with false negative nucleic acid test results.

2. Differential diagnosis

Many respiratory diseases also have clinical manifestations of fever, sputum and chest tightness, which can be distinguished by CT.

3. Assessment of the condition

CT manifestations can accurately evaluate the severity of different clinical types of diseases and provide a basis for further treatment. In the early stage of COVID-19, multiple small patchy shadows and interstitial changes are evident in the outer lungs under CT. Then they develop into ground-glass density shadows and infiltration shadows in both lungs. In severe cases, pulmonary consolidation may occur. Therefore, imaging manifestations can be used to assess the degree of disease progression.

05

How to determine COVID-19 infection

Will it further develop into pneumonia?

High fever does not subside, and the body temperature is generally above 39°C. If the high fever lasts for a long time, more than 3 days, and still does not subside; or if the fever appears at the beginning, gets better after treatment, and then reappears, be careful, whether there is lung inflammation.

The cough symptoms persist, or there is difficulty breathing, decreased blood oxygen saturation, increased sputum, darker sputum color, or other worsening symptoms.

If the above changes in condition occur, especially for high-risk groups who are over 65 years old and have underlying diseases such as chronic respiratory diseases, cardiovascular and cerebrovascular diseases, and tumors , they need to go to the hospital for evaluation and a chest CT scan in time.

For most patients infected with the new coronavirus, if the cough is mainly dry, without much sputum, the fever improves quickly, the cough symptoms are gradually improving, and there are no other obvious symptoms, they can be observed with confidence without the need for a chest CT scan.

06

Summarize

Not all COVID-19 infections require chest CT scans. The main purpose of chest CT scans is to determine the severity of pneumonia. For most patients with mild symptoms, chest CT scans are not necessary.

For elderly people whose condition is more serious, with obvious dyspnea, wheezing, or with underlying diseases, in order to determine whether they have pneumonia and the possibility of infection with other pathogens, CT examination should be performed as soon as possible to assist in diagnosis, differential diagnosis and assessment of the condition.

Author: Sun Siqing, Chief Physician, Department of Respiratory and Critical Care Medicine, Nanjing Second Hospital

Reviewer: Li Dongzeng, Chief Physician, Department of Infectious Diseases, Beijing You'an Hospital, Capital Medical University