TEMPO.CO, Jakarta - Influenza A is currently making rounds across Indonesia, with the Indonesian Pediatrician Association (IDAI) calling for regional mapping of the spread, especially since some cases have been found in children.
The latest data from the Ministry of Health as of September 19, 2026, shows that the proportion of positive influenza cases in the 36th week of surveillance reached 46 percent, up from 35 percent the previous week. Of the 185 specimens examined, there were 86 positive influenza cases, consisting of 76 influenza A(H1N1)pdm09, eight A(H3N2), and two influenza B Victoria. Forty-two percent of the detected influenza cases were in the 0-4 age group.
Nevertheless, the Ministry of Health said the overall level of influenza activity remains low, with the situation under control. While acknowledging that the spread of influenza A is notable, it said not every case discovery leads to an outbreak.
So, what exactly is influenza A, and how dangerous is it?
What is influenza A?
Influenza A is a type of respiratory infection in humans. The World Health Organization (WHO) explains that seasonal influenza in humans is most often caused by influenza viruses types A and B. Influenza A is further divided into several subtypes based on two proteins on the surface of the virus: hemagglutinin, or H, and neuraminidase, or N.
Some influenza A subtypes circulating in humans include A(H1N1)pdm09 and A(H3N2).
A(H1N1)pdm09 was the trigger to the 2009 influenza pandemic. After the pandemic ended, this virus became one of the seasonal influenza viruses that continued to circulate.
Therefore, when H1N1 reappears in current influenza reports, it does not necessarily mean the 2009 pandemic is back. H1N1pdm09 has become part of the seasonal influenza viruses circulating in humans.
How is influenza A transmitted?
Influenza A can spread relatively easily from one person to another, typically through respiratory droplets when an infected person coughs, sneezes, or speaks. The risk of transmission can also increase when someone is in a crowded place and has close contact with someone who is sick.
This is why influenza can spread quite quickly in environments such as schools, workplaces, homes, healthcare facilities, and other enclosed spaces.
Influenza A can also circulate throughout the year. The Ministry of Health notes that influenza activity can be influenced by weather factors and has the potential to increase during the rainy season.
What are the symptoms?
There's not much difference in symptoms between influenza A and the others. The WHO states that influenza symptoms usually appear all of a sudden. Some common complaints include fever, cough, sore throat, runny nose, headache, muscle and joint pain, and severe fatigue.
The cough can also last longer than other symptoms, even up to two weeks or more.
For some people, the symptoms can feel like a common cold and improve on their own in about a week. However, there are also conditions where influenza can develop into a more serious illness.
So, is influenza A dangerous?
The answer is yes, it's possible for influenza A to become more dangerous, especially in higher-risk groups.
The WHO lists children under five, the elderly, pregnant people, and people with certain chronic diseases as groups at higher risk of developing severe influenza.
Chronic diseases that can exacerbate the risk of complications include heart, lung, kidney, liver, metabolic disorders, and several conditions that affect the immune system.
Complications of influenza can include pneumonia, or lung infections. In severe cases, the infection can also lead to sepsis and organ damage.
Influenza can also worsen pre-existing conditions, such as asthma or lung and heart disease.
Therefore, the assumption that influenza is just a "common cold" is not always accurate. The risk of illness depends greatly on the condition of the infected person.
What about influenza A(H3N2) subclade K?
The name influenza A(H3N2) subclade K was also widely discussed in Indonesia throughout 2026.
The Ministry of Health previously issued a special circular regarding the management of influenza A(H3N2) subclade K. The document noted that subclade K was first detected in Indonesia in September 2025, and as of January 10, 2026, 74 cases had been detected in 13 provinces. The Ministry of Health also noted that the majority of cases showed mild to moderate symptoms.
In the latest surveillance report, as of September 19, 2026, the Ministry of Health still recorded the presence of H3N2 subclade K in 13 provinces. However, surveillance data also showed no positive influenza cases admitted to the ICU during week 36 at the sentinel hospitals examined.
When to see a doctor?
Flu usually improves with rest and adequate fluid intake. However, the public should be more vigilant if symptoms worsen or persist.
Difficulty breathing, shortness of breath, chest pain or pressure, confusion, severe dizziness, extreme weakness, dehydration, or a condition that improves and then worsens are signs that require medical attention.
The Ministry of Health also urges the public to immediately seek medical attention if symptoms worsen or persist for more than three days.
High-risk groups such as young children, the elderly, pregnant women, and people with underlying health conditions should also not wait until their symptoms become severe to seek medical attention.
Read: UGM Professor Urges Vigilance Over 'Cicada' Covid-19 Variant
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