KEY TAKEAWAYS:
- Indonesia’s national influenza positivity rate rose to 46 percent for the week ending 19 September 2026, up from 35 percent the previous week, with Influenza A(H1N1)pdm09 accounting for 76 of the 86 positive specimens. Despite the rise, Indonesia’s Ministry of Health classifies national influenza activity as low and the situation as stable and controlled, consistent with normal seasonal circulation.
- Children under four account for 42 percent of detected cases, and cases span 13 provinces, with East Java (particularly Surabaya) and South Kalimantan each accounting for roughly 24 percent of the reported distribution.
- Surabaya has seen a pediatric surge in outpatient and emergency-room demand, but hospital bed occupancy remains within baseline capacity and no influenza-positive patients were admitted to intensive care during the reporting week.
- Businesses are advised to maintain routine hygiene and ventilation measures without overreacting to the positivity increase, while individuals — especially those in high-risk groups — should seek prompt medical advice for worsening symptoms.
Indonesia is seeing a rise in seasonal influenza activity heading into late September 2026. This is general public-health information drawn from Ministry of Health surveillance data and open-source reporting, not personalised medical advice — anyone with symptoms should consult a healthcare professional.
What is happening with influenza in Indonesia in September 2026?
According to Indonesia’s Ministry of Health National Influenza and COVID-19 Case Surveillance Report published on 19 September, the national laboratory positivity rate rose to 46 percent for the week ending 19 September, up from 35 percent the previous week, with 86 of 185 tested specimens positive for influenza. Of these, 76 were Influenza A(H1N1)pdm09, eight were A(H3N2) and two were Influenza B (Victoria lineage), confirming H1N1pdm09 as the dominant circulating subtype. Influenza-like illness (ILI) visits to sentinel Puskesmas health centres also rose, from 0.31 percent to 0.40 percent of total visits, with the 5–14-year age group accounting for 45 percent of ILI cases. Hospital-based surveillance across 35 sentinel hospitals recorded a rise in influenza positivity to 31.7 percent from 20.4 percent the previous week, though no influenza-positive patients required intensive care during the reporting period.
Which provinces are seeing the most cases?
Ministry of Health surveillance data shows detections spread across 13 provinces, with East Java and South Kalimantan each accounting for roughly 24 percent of the reported distribution, followed by West Java, Jakarta, South Sumatra, North Sumatra, Bali, East Nusa Tenggara, West Nusa Tenggara and North Sulawesi in smaller numbers. Surabaya, in East Java, has drawn particular attention after local media reported high occupancy in some hospitals’ pediatric wards and emergency departments; the Surabaya Health Office says it is monitoring bed and staffing availability, and confirms the majority of affected patients are being managed as outpatients without a corresponding rise in cases requiring intensive care.
Who is most at risk from the current influenza activity?
Children under four account for 42 percent of all surveillance-detected cases, and children under two are considered the highest-vulnerability group. Adults aged 65 and above, pregnant women, healthcare workers, and people with chronic cardiovascular, pulmonary, renal, hepatic, metabolic or immunocompromising conditions also face a higher risk of complications such as pneumonia, ARDS or severe exacerbation of existing illness. Most cases, however, resolve within five to seven days of acute symptoms, sometimes followed by a lingering dry cough and fatigue for two weeks or more.
Why does the Ministry of Health call the situation ‘low risk’ despite rising positivity?
Indonesia’s Ministry of Health continues to classify national influenza activity as low and the overall situation as stable and controlled, describing the rise in positivity as consistent with normal seasonal circulation rather than an unusual escalation. Because Indonesia’s tropical climate allows influenza to circulate year-round rather than in a single winter season, periodic increases in laboratory positivity are expected. The distinguishing factor authorities are monitoring closely is disease severity — and with hospital bed occupancy within baseline capacity and no rise in ICU admissions, the current increase is being treated as a routine seasonal uptick rather than a public health emergency.
What should businesses and travellers do to prepare?
Organisations operating in Indonesia, particularly in East Java, South Kalimantan, West Java and Jakarta, are advised to maintain routine health and safety protocols: encourage symptomatic employees to stay home or work remotely, strengthen ventilation in shared spaces, maintain accessible hand-hygiene facilities, and increase cleaning of high-touch surfaces. Businesses are specifically cautioned against unnecessary panic or broad operational restrictions based solely on the positivity increase, given the Ministry of Health’s low-risk classification. Individuals and travellers should practise frequent hand hygiene, wear a mask in crowded or enclosed settings if symptomatic, avoid inappropriate self-medication with antibiotics, and seek prompt medical attention if symptoms include difficulty breathing, persistent high fever, severe weakness, chest pain or confusion.
Frequently asked questions
Is this a new flu strain in Indonesia?
No. Influenza A(H1N1)pdm09 remains the dominant circulating subtype, alongside smaller proportions of A(H3N2) and Influenza B (Victoria lineage) — both established seasonal subtypes rather than a new or unusual strain.
Is Surabaya’s hospital system under strain?
Surabaya has seen increased outpatient and emergency-room demand, particularly among pediatric patients, but hospital bed occupancy remains within baseline capacity and no corresponding rise in ICU admissions has been reported.
Should travellers to Indonesia be worried right now?
Indonesia’s Ministry of Health classifies the national situation as low risk and controlled. Travellers are advised to follow routine precautions — hand hygiene, masking if unwell, and prompt medical attention for worsening symptoms — rather than avoid travel.
Download the full advisory now
datasurfr’s Special Advisory on Influenza Cases in Indonesia carries the complete province-by-province case data, the full symptom and severity assessment tables, and a detailed dos-and-don’ts guide with emergency contacts. Download the full advisory now to brief your workplace health and continuity teams.
Filed under: APACThreat Intelligence Special Reports
