How many days does the novel pneumonia take to develop?

Written by Chen Jian
Infectious Disease
Updated on May 17, 2025
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After being infected with the novel coronavirus pneumonia, symptoms generally appear within three to seven days, with the shortest onset reported within one day and the longest at 27 days. However, most patients develop symptoms within two weeks, typically exhibiting respiratory symptoms post-onset. The novel coronavirus primarily attacks the lower respiratory tract, including the trachea, bronchi, and lungs. Patients often experience recurring fever, with temperatures generally ranging between 38 to 39°C, lasting over 72 hours, accompanied by significant coughing. In the early stages, there is usually no noticeable expectoration, presenting as a dry cough. Most patients also experience significant fatigue. If the condition progresses, patients may suffer from shortness of breath and decreased blood oxygen saturation, leading to apparent respiratory distress. In severe cases, patients may experience respiratory failure and even death.

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Written by Li Jian Wu
Pulmonology
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Pneumonia symptoms in children

Children presenting with pneumonia primarily exhibit symptoms related to respiratory infections, with fever often as a typical manifestation. Common symptoms include sudden chills, high fever, fatigue, headache, nausea, and vomiting, followed by an irritative dry cough. As the condition progresses, the dry cough turns into a productive cough with phlegm, accompanied by difficulty breathing, chest pain, and expectoration. Some may also show signs of oxygen deprivation such as cyanosis of the lips and changes in nail color. Active chest X-ray and routine blood tests are necessary for diagnosis.

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Written by Yang Feng
Pulmonology
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Symptoms of pneumonia in children

Pneumonia is a particularly common infectious disease of the respiratory system, and infants and young children are especially susceptible to pneumonia because their immune systems are much weaker than those of healthy adults. When infants and young children develop pneumonia, their symptoms differ from adults; they often exhibit only fever, crying, nausea, vomiting, etc. The symptoms of coughing and phlegm are relatively less obvious, making the diagnosis of pneumonia in infants and young children somewhat more difficult. If a patient exhibits fever, auscultation and routine blood tests can be used to preliminarily determine the presence of an infection. If pneumonia is suspected, further comprehensive imaging examinations can be conducted to confirm the diagnosis.

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Written by Li Jiao Yan
Neonatology
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The function of the pneumonia vaccine

Pneumonia vaccines are generally aimed at preventing infections caused by Streptococcus pneumoniae. There are two common types of vaccines: the 23-valent polysaccharide vaccine, which is suitable for high-risk populations over two years old, and the 7-valent or 13-valent conjugate vaccines, which are mainly used for vaccinating infants under two years of age. Streptococcus pneumoniae is the most common and widespread bacterium causing pneumonia, and pneumonia caused by this bacterium is also the most prevalent worldwide. It is also the most significant pathogen in community-acquired pneumonia in children and a major cause of otitis media, meningitis, and bacteremia in children. The pneumonia vaccines mainly target common serotypes of Streptococcus pneumoniae, such as the 7-valent or 13-valent, designed to prevent infections from seven or thirteen serotypes, respectively, while the 23-valent vaccine aims to prevent infections from 23 serotypes. These pneumonia vaccines play a significant protective role in preventing infections caused by Streptococcus pneumoniae, however, they cannot prevent all cases of pneumonia.

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Written by Li Jian Wu
Pulmonology
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How long does the pneumonia vaccine last?

After receiving the pneumonia vaccine, the body generates an immune response that produces antibodies. Typically, these antibodies provide lifelong immunity. Patients with weak constitutions might need a booster shot every 3-5 years after vaccination, which generally can also lead to lifelong immunity. Vaccinations should be administered at local, formal medical institutions. One can visit the local centers for disease control and prevention to get vaccinated. During the vaccination period, if there are any adverse reactions, they should be addressed promptly. After receiving the vaccine, it is advisable to remain at the medical facility for half an hour for observation before leaving, to prevent the occurrence of adverse reactions.

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Written by Hu Xue Jun
Pulmonology
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Is pneumonia contagious?

Pneumonia can be divided into many types, including viral pneumonia, bacterial pneumonia, and those caused by special bacteria such as tuberculosis bacillus, and atypical bacteria such as Legionella, Mycoplasma, Chlamydia, etc. Generally, pneumonia does not cause large-scale disseminated transmission, because most people have normal immune systems that can resist these less virulent bacteria; however, in populations with lower immunity, inhaling droplets from patients with bacterial pneumonia can potentially lead to pneumonia. However, pneumonias caused by "SARS", anthrax, pneumonic plague, etc., are highly contagious and can cause large-scale transmission through droplets, and these are strictly controlled infectious diseases in our country. In cases of open tuberculosis, the patient's sputum and cough droplets might contain the pathogen, which could then infect those in close contact. Infectious pneumonia typically has an abrupt onset, with an incubation period of 2-10 days, and fever as the initial symptom, generally above 38℃, possibly accompanied by chills, coughing, scant sputum, occasional bloody sputum, palpitations, shortness of breath, and in some cases, difficulty breathing. It may also be accompanied by muscle soreness, headaches, joint pain, fatigue, and diarrhea.