Flu hits Kenyans the hardest in October, surveillance data shows. Kenya experiences two flu waves every year, with the bigger one expected in October, an analysis by the Ministry of Health and its partners shows.
The finding could help hospitals plan ahead and stock enough medicine, nurses and beds before the expected wave coincides with El Niño-fuelled rains.
The analysis shows the country usually records a smaller flu wave in March and a larger one in October, challenging the assumption that Kenya’s biggest flu season occurs during the June-July cold period.
The study was conducted by scientists from the Kenya Medical Research Institute, Ministry of Health and United States Centers for Disease Control and Prevention. It was published this month in the journal ‘Influenza and Other Respiratory Viruses.
’Kenya’s position on the equator means influenza does not follow the clear seasonal patterns seen in countries farther from the equator. While flu tends to peak during winter in some countries, in Kenya it can occur at different times of the year.
The researchers analysed data collected between 2019 and 2025 from nine hospitals, including facilities in Nakuru, Nyeri, Kakamega and Marsabit, Kenyatta National Hospital and hospitals in the Kakuma and Dadaab refugee camps.
Health workers recorded patients presenting with coughs, fever and breathing difficulties, while some were tested for influenza.
The researchers used the data to develop three severity levels — low, high and very high — providing a way to determine whether a respiratory illness or flu season is mild or severe.
The results for 2024 and 2025 were largely reassuring, with overall sickness levels remaining low. However, children were affected more than adults. Respiratory illness accounted for about a third to almost half of hospital visits in paediatric wards, compared with roughly one in 10 visits among adults.
In 2024, influenza cases among adults rose sharply in October, crossing into moderate severity for about two weeks. Last year the biggest wave came in November, although national severity remained low.
Researchers said the tool could help officials determine when to deploy additional medicines, nurses and beds and guide the timing of vaccination campaigns.
However, they cautioned that the system needs more data. The study covered only nine hospitals and 2020 was excluded because Covid-19 disrupted hospital records.
The researchers plan to continue collecting data and expand coverage to more facilities, which they say will improve the warning system’s accuracy.
