Super Flu Cases Explode in the US, How about in Indonesia?

The spread of the super flu, or influenza A coded H3N2 subclade K, is becoming increasingly massive in the United States (US).

According to data from the US Centers for Disease Control and Prevention (CDC), reported by CNN, there have been at least 7.5 million cases of this disease. As of December 20, 2025, 81,000 have been hospitalized and 3,100 have died due to the flu this season.

The US states with the highest number of cases are Colorado, Louisiana, New Jersey, New York, and South Carolina.

According to observations by Michael Osterholm, Director of the Center for Infectious Disease Research and Policy at the University of Minnesota, the flu season in the region has just begun. However, it is still very difficult to ascertain the development of these cases.

"What we are seeing right now is a very rapid surge in cases," Michael Osterholm told CNN.

How is the development of these cases in Indonesia?

Citing Katadata, the Ministry of Health detected subclade K in Indonesia as early as August 2025 through the sentinel ILI-SARI surveillance system in various healthcare facilities.

This finding was further supported by the results of whole genome sequencing (WGS) completed on December 25, 2025, which confirmed the presence of the variant.

Out of a total of 843 confirmed positive influenza specimens, the Ministry of Health examined 348 samples via WGS. All identified variants are known variants currently circulating globally within the WHO surveillance system.

By the end of December 2025, the Ministry of Health recorded 62 cases of influenza A(H3N2) subclade K spread across eight provinces, with the highest number of cases in East Java, South Kalimantan, and West Java. The majority of patients were women and children.

This flu disease was also first detected in the US in August 2025. This variant has spread to at least 80 countries.

Superflu refers to subclade K, a new branch of the influenza A (H3N2) virus that has circulated as seasonal flu for decades.

Citing the website of the global alliance for vaccines and immunization, Gavi.org, scientists first detected subclade K in mid-2025. They noted its rapid spread in several countries, such as the UK, Japan, and parts of Europe.

Despite carrying several genetic mutations, the World Health Organization (WHO) believes that subclade K does not show unusual evolutionary patterns or more severe symptoms compared to other H3N2 influenza viruses.

"To date, we have not seen any signs of unusual or concerning viral evolution," said Nicola Lewis, Director of the World Influenza Centre at The Francis Crick Institute.

Prima Yosephine, Director of Infectious Diseases at the Ministry of Health, explained that super flu patients generally experience symptoms similar to seasonal flu, such as fever, cough, runny nose, headache, and sore throat.

(Read Katadata: 62 Superflu Cases in Indonesia: Entered Since August, Majority of Patients are Children)