Flu in Bulgaria: Which strains dominate and what to expect in the winter of 2025/2026

23.11.2025 | Medicine

The incidence of influenza and acute respiratory infections at the end of November 2025 is increasing; health authorities predict a particularly strong season with the leading strain H3N2. Vaccination and preventive measures remain key.

Снимка от Kristoffer Trolle from Copenhagen, Denmark, Wikimedia Commons (CC BY 2.0)

The flu season in Bulgaria is already on the rise: to date, the official data of the Ministry of Health indicate over 2905 cases of influenza and acute respiratory infections in 346,619 observed persons - morbidity 83.79 per 10,000 people, which is an increase compared to the average indicators for this stage of autumn.

The leading danger this winter is the mutating strain of influenza type A (H3N2), which epidemiologists warn could provoke the most severe season of the last decade. Circulating variants of H1N1 (the so-called "swine flu") and virus B/Victoria are also reported. A flu epidemic was already declared in 12 regions during the previous season.

According to the assessment of the World Health Organization and the national center, the flu will affect nearly 10% of the population, and in pandemic scenarios - up to 35%. The most vulnerable are the elderly, chronically ill, children and pregnant women.

The main symptoms are sudden high fever, muscle and joint pain, headache, severe fatigue, cough and sore throat. Complications are possible - pneumonia, meningitis, bronchiolitis. Health authorities recommend timely vaccination - 580,000 vaccines have been ordered, of which 400,000 are free for people over 65 years of age.

Experts advise avoiding large indoor gatherings, maintaining excellent hygiene, wearing masks when symptoms and when in contact with risk groups. Symptomatic treatment (rest, hydration, paracetamol), and in case of complications - a quick consultation with a doctor are mandatory.