Influenza is a common infectious disease in children, caused by multiple circulating viral strains. Among these, influenza A is of particular clinical concern, as it may lead to serious complications if not detected early and managed appropriately. What is influenza A in children, what are its clinical manifestations, and how should it be treated are questions frequently raised by parents and caregivers.
What is influenza A?
Influenza A is an acute respiratory infection caused by influenza A viruses, including subtypes such as A/H1N1, A/H3N2, A/H5N1, and A/H7N9.
Clinically, influenza A may be easily mistaken for the common cold due to overlapping symptoms, making early differentiation challenging. However, influenza A should not be underestimated. The disease can progress rapidly and carries the risk of severe complications if not properly managed.
Moreover, influenza A viruses possess significant mutation potential and have been responsible for major outbreaks, epidemics, and even global pandemics, posing substantial impacts on public health and societal well-being.
Common influenza A virus subtypes
Influenza A viruses comprise multiple subtypes, of which the following are among the most commonly encountered in clinical practice and public health surveillance.
Influenza A/H1N1
This viral strain was recognized by the World Health Organization in 2009. Initially, influenza A/H1N1 was referred to as “swine flu” because scientists believed it originated from pigs.
Influenza A/H1N1 has a very rapid transmission rate and can easily spread widely, leading to outbreaks and even dangerous pandemics.
The virus may cause secondary infections, multiorgan failure, and severe pneumonia, and can be fatal, particularly in individuals with chronic underlying conditions.
Each year, an estimated 250,000 to 500,000 deaths worldwide are attributed to influenza.
Influenza A/H5N1
The influenza A/H5N1 virus originates from poultry and can be transmitted to humans. It has been reported in multiple countries and has resulted in numerous fatalities. From December 2003 to June 2008, 243 deaths were recorded globally out of 385 confirmed human cases across 15 countries.
Influenza A/H3N2
Influenza A/H3N2 was first identified in the United States in 1968. This strain caused a major pandemic, resulting in approximately one million deaths worldwide.
Currently, A/H3N2 circulates as a seasonal influenza A virus and is capable of infecting humans, birds, and other mammals.
Influenza A/H7N9
In March 2013, influenza A/H7N9 was first reported in China and subsequently spread rapidly, raising significant global concern. This strain is considered highly pathogenic, with a strong capacity for transmission to humans.
After entering the human body, A/H7N9 can replicate rapidly in organs including the respiratory, gastrointestinal, urinary, and reproductive systems. High viral loads have been detected in bodily secretions such as nasal discharge, tears, saliva, and feces.
All confirmed human cases of A/H7N9 infection have been associated with pneumonia. Severe cases, if not treated promptly, may progress to respiratory failure and death. Most infected individuals require medical intervention, as spontaneous recovery is uncommon.
Children at increased risk of influenza A infection
Anyone can contract influenza A, particularly children. However, the following pediatric groups are at higher risk of infection:
- Children under five years of age, especially those younger than two years
- Children who have not received influenza vaccination
- Children in close contact with individuals infected with influenza or those at high risk of influenza infection
- Children who do not practice proper hand hygiene or fail to disinfect their hands after contact with surfaces contaminated with influenza A virus
These factors significantly increase susceptibility to infection and potential disease transmission.
Clinical manifestations of influenza A in children
Children with influenza A may present with mild to severe symptoms, depending on disease severity. Common clinical manifestations include:
- High fever, which may reach 39.4°C to 40.5°C
- Cough
- Rhinorrhea or nasal congestion
- Sore throat
- Headache
- Fatigue, poor appetite, or refusal to feed in infants
- Myalgia and generalized body aches
- Vomiting and diarrhea in some cases
- Ear pain or conjunctival redness
- Febrile seizures associated with high fever
When these symptoms occur, parents should not underestimate the condition. Prompt medical evaluation is recommended, as influenza A carries the risk of serious complications if not diagnosed and managed appropriately.
Transmission routes of influenza A in children
Influenza A spreads rapidly from person to person. Transmission among young children occurs particularly quickly due to their immature immune systems and close contact in communal settings.
The influenza A virus is present in high concentrations in respiratory secretions, including saliva, nasal discharge, and pharyngeal secretions. The most common route of transmission is via respiratory droplets generated when an infected child coughs, sneezes, or talks.
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These droplets may directly contact the mucous membranes of the mouth or nose of nearby children, leading to infection. Transmission may also occur indirectly when a child touches surfaces or objects contaminated with the virus and subsequently touches their mouth or nose.
Is influenza dangerous in children?
Influenza A is a common pediatric illness but carries significant potential risks. It may adversely affect a child’s health and, in severe cases, become life threatening.
Influenza A viruses comprise multiple subtypes and can survive for prolonged periods in the external environment, contributing to high transmissibility. In addition, clinical manifestations often resemble those of the common cold, leading some parents to underestimate the condition and delay medical evaluation and treatment. Such delays may increase the risk of serious complications.
If not promptly and appropriately managed, influenza A in children may progress to acute respiratory failure, characterized by dyspnea, hemoptysis or blood tinged sputum, severe pneumonia, and hypoxemia. Without timely medical intervention, these complications may result in fatal outcomes.
Complications of influenza A in young children
In addition to typical influenza symptoms such as rhinorrhea, nasal congestion, sore throat, and cough, influenza A may be accompanied by more severe manifestations, including muscle aches, decreased activity, vomiting, excessive thirst, and dehydration.
Young children with influenza A may refuse breastfeeding or feeding, have poor appetite, and present with cold palms and soles. In some cases, children may develop high fever accompanied by seizures.
Some complications that children may develop when infected with influenza A include respiratory failure, pneumonia, otitis media, meningitis, laryngotracheobronchitis, myocarditis, and secondary bacterial infections.
If not detected and managed promptly, these complications may seriously affect a child’s health and can even be life threatening.
When should a child be taken to the hospital?
Influenza A often progresses rapidly and may pose serious health risks if not treated promptly. Parents should seek immediate medical care if the child develops any of the following signs:
- Persistent high fever above 39°C that does not respond to antipyretic medication
- Tachypnea or difficulty breathing
- Seizures
- Marked lethargy, excessive drowsiness, refusal to eat, recurrent vomiting, or cold extremities
Early medical evaluation is essential to prevent severe complications and ensure timely intervention.
Home care guidance for children with influenza A
When a child is diagnosed with influenza A, parents should implement the following measures to ensure appropriate care and to minimize transmission to others:
- Isolate the child in a separate room for at least 7 days from the onset of initial symptoms. Isolation should be maintained for at least one additional day after symptoms have completely resolved.
- Ensure the room is clean and well ventilated, cool during summer and warm during winter. The child should ideally bathe and use a separate bathroom. If a private bathroom is unavailable, the child should wear a mask when leaving the room, avoid close contact, and practice thorough hand hygiene after using shared facilities.
- Avoid taking the child outside unless absolutely necessary. If leaving the room is required, the child should wear a mask and avoid contact with shared household items.
- Maintain adequate nutrition. Provide a balanced diet including all essential nutrient groups. Offer soft, easily digestible foods, increase intake of vegetables and fruits, and encourage sufficient fluid consumption to prevent dehydration.
- Strictly adhere to the physician’s prescribed treatment regimen. Parents should not self prescribe medications or adjust dosages without medical guidance, as inappropriate use may cause harm.
Preventive measures against influenza A in children
Influenza A not only causes fatigue and discomfort in children but also carries the risk of serious complications. Therefore, early and proactive prevention is essential.
Parents should implement the following measures to reduce the risk of influenza A infection:
- Maintain daily personal hygiene and ensure frequent handwashing for the child.
- Have the child wear a mask when going outside.
- Avoid taking the child to crowded places, particularly during influenza outbreaks.
- Limit close contact with individuals who are at high risk for influenza or who are suspected of being infected.
- Regularly clean and disinfect the home environment.
- Ensure the child receives annual influenza vaccination.
- Provide adequate vitamins and minerals to support immune function.
- Seek early medical evaluation if the child develops symptoms suggestive of influenza, such as cough, rhinorrhea, or fever.
Vaccination is the most effective preventive measure against influenza A in children
Immunization remains the most effective strategy for preventing influenza A in pediatric populations. Experts recommend that children receive seasonal influenza vaccination annually to reduce the risk of infection and associated complications.
Hong Ngoc General Hospital is among the trusted vaccination centers chosen by many parents. Prior to immunization, each child undergoes thorough pre-vaccination screening and health assessment to ensure maximum safety.
The hospital maintains an adequate supply of vaccines directly imported from the United States, France, Belgium, Germany, and other countries, with formulations appropriate for different pediatric age groups. A stringent quality control process is implemented from importation through transportation and cold chain storage to ensure optimal vaccine integrity at the time of administration.
To protect your child from potentially serious influenza A complications, do not overlook annual vaccination for both your child and family members.
To schedule an influenza A vaccination appointment, please register here:
Note: The information provided in this article by Hong Ngoc General Hospital is intended for reference purposes only and does not substitute for professional medical diagnosis or treatment. Patients should not self-medicate. For an accurate assessment of their medical condition, individuals are advised to seek direct consultation at a healthcare facility for clinical evaluation, diagnosis, and appropriate treatment recommendations from a qualified physician.
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