During this time of frequent weather changes, parents may often hear about outbreaks of influenza. Influenza is a contagious illness that commonly spreads during the winter season (January–March) and the rainy season (June–October) each year. People of all ages can be infected; however, children are more susceptible to influenza than adults.
How Is Influenza B Different from the Common Cold?
Influenza and the common cold are caused by different types of viruses and vary in severity. Influenza is caused by infection with the influenza virus, whereas the common cold is caused by other viruses, such as rhinovirus and adenovirus.
The common cold usually causes mild symptoms, such as nasal congestion, a runny nose, coughing and sneezing, throat irritation, and typically does not involve a high fever or muscle aches.
Influenza usually causes more severe symptoms than the common cold.
These include a high fever, muscle aches, extreme fatigue, a runny or congested nose, sore throat, coughing, and more intense headaches. Influenza is also more likely to lead to serious complications than the common cold—especially among high-risk groups. In severe cases, complications such as pneumonia may occur and can even be life-threatening.Learn more about pneumonia in children
There are three types of influenza viruses that infect humans: A, B, and C. However, only influenza A and B commonly cause outbreaks. Influenza C is a much milder virus, rarely causes widespread infection, and usually results in very mild symptoms; therefore, vaccination against influenza C is not necessary.
Influenza A and B present very similar symptoms, making it difficult to distinguish between the two based on symptoms alone. Laboratory testing, such as a swab test, is required to accurately identify the virus type.
Influenza A
Influenza A is divided into several subtypes, with H1N1 and H3N2 being the most commonly circulating strains. This type of influenza is generally more severe, mutates more easily, and can be transmitted from animals to humans. Symptoms are often more serious than those of influenza B, including higher fever, more intense muscle aches, and a greater risk of complications such as pneumonia and meningitis.
Influenza B
Influenza B is classified into two lineages: Victoria and Yamagata. It usually causes milder illness than influenza A, mutates less frequently, and spreads only from person to person. Outbreaks tend to occur at a more localized level. Common symptoms include a dry cough, sore throat, headache, nasal congestion, and a moderate fever. In some cases, symptoms may resemble those of a mild common cold.
How Is Influenza B Transmitted in Children?
Influenza B is spread through respiratory secretions such as phlegm, nasal discharge, and saliva. Children can become infected through direct exposure to coughs or sneezes, by inhaling respiratory droplets released when an infected person coughs or sneezes, or through contact with contaminated nasal secretions or phlegm. Symptoms typically appear within 1–4 days after exposure to the virus.
In young children or individuals with underlying medical conditions, influenza can more easily lead to complications. Common complications include middle ear infections, sinusitis, bronchitis, and pneumonia, which are more likely to occur in high-risk individuals. Less common but serious complications include myocarditis, peripheral neuritis, and encephalitis.
Checking for Influenza B Symptoms in Your Child
When a child is infected with Influenza B, they may show the following symptoms:
- Sudden high fever and chills;
- Body and muscle aches – young children may not be able to express this; instead, they may appear very tired, weak, less active, or sleep more than usual;
- Clear runny nose and nasal congestion;
- Dry cough, sore throat, and loss of appetite;
- Diarrhea, nausea, and vomiting; and
- In young children, high fever may cause seizures or unusual behavior, such as confusion or strange speech.
How to Protect Your Child from Influenza B
- Avoid crowded and poorly ventilated places for extended periods;
- Keep your child away from people who are sick with the flu;
- Wear face masks regularly to reduce the risk of infection;
- Wash hands frequently with soap and water, or use alcohol-based hand sanitizer—especially before and after meals, or after returning home;
- Avoid sharing personal items such as cups, straws, utensils, towels, or handkerchiefs;
- Maintain your child’s overall health by providing nutritious food and ensuring adequate rest;
- Vaccinate your child against influenza every year. The virus strains circulating each year can change, so the annual vaccine is updated accordingly; and
- If your child becomes infected, keep them home from school for 5–7 days to prevent spreading the virus.
Heartfelt thanks to Ms. Piyarat ‘Ann’ Lertbannaphong, M.D., a specialized pediatrician.
Crated At 04/02/2026
