Switzerland expects seasonal flu wave to begin in mid-December

Switzerland's flu wave is expected around mid-December, giving health services and residents several weeks to prepare as autumn respiratory infections gather pace. The Federal Office of Public Health says influenza and respiratory syncytial virus remain at very low levels for now. Covid-19 is already gaining ground in some regions.

The pattern is familiar to Swiss health authorities. Covid-19 has generally reached its autumn peak before influenza and RSV become more active during the winter season. The current increase therefore comes ahead of the period when hospitals, care homes and family doctors typically face a broader mix of respiratory illness.

The FOPH has cautioned against treating the December forecast as a precise timetable. The scale of the wave remains difficult to assess because several factors can alter transmission and pressure on the health system. Population immunity, the virus variants circulating at the time and weather conditions will all influence the result.

For now, surveillance data point to a developing season rather than a major outbreak. That assessment covers Switzerland and Liechtenstein, where the latest weekly Covid-19 figures have risen above summer levels while remaining below the numbers recorded at the same point last year.

Around 120 Covid-19 cases a week are now being reported in Switzerland and Liechtenstein, according to the FOPH's surveillance data. During most summer weeks, the figure stood between 10 and 20 cases. The rise is clear, although the virus is circulating less widely than during the same period in 2025.

More than 500 cases were recorded in the first week of October last year. The comparison places the current increase in context: Covid-19 is returning as the autumn respiratory season develops, but current reporting remains below the level seen twelve months earlier.

The Sentinella surveillance system shows flu and RSV at very low levels. Sentinella draws on reporting from participating medical practices and helps authorities track the movement of respiratory infections across the country. The system also captures the sequence that the FOPH has observed in recent years, with Covid-19 activity commonly preceding the winter rise in influenza and RSV.

Other viruses are also circulating. Rhinoviruses, which cause many common colds, are active in autumn but are not included in the FOPH reporting system. That means the full burden of minor respiratory illness cannot be read from the official flu, Covid-19 and RSV figures alone.

RSV and influenza remain limited for now, but both viruses can create serious illness, particularly among young children. The FOPH has grouped them with Covid-19 in its winter outlook because their impact will depend on how transmission develops after the current autumn phase.

RSV is a major concern for paediatric services during the colder months. The source material does not provide a forecast for hospitalisations or identify specific cantons with higher RSV activity. It does show that the virus remains under surveillance alongside flu and Covid-19, with authorities watching for a broader seasonal increase.

The timing and size of an outbreak can shift with several conditions. Immunity levels in the population may affect how easily viruses spread and how severely people become ill. New variants can change the pattern of infection, while weather conditions influence how much time people spend indoors and how respiratory viruses circulate.

That uncertainty has practical consequences for Swiss health services. General practitioners, children's hospitals, care homes and pharmacies must prepare for overlapping waves rather than a single predictable peak. The FOPH's mid-December estimate provides a planning window, while the surveillance data will continue to determine whether the season follows the expected course.

Flu vaccine deliveries are running behind schedule at some providers, including doctors' surgeries, hospitals, care homes and pharmacies. Simon Ming, a spokesperson for the Federal Office of Public Health, said the delays do not amount to a shortage. People at higher risk, as well as other members of the population who want vaccination, still have time to arrange it before the expected winter wave.

The message matters because the FOPH does not expect the full flu wave until mid-December. The additional weeks may allow delayed shipments to reach healthcare providers and give eligible people time to seek advice from their doctor or pharmacy. The source does not specify how many providers are affected or when each delivery will arrive.

Switzerland's winter respiratory picture will continue to change. Covid-19 is already above its summer reporting range, while flu and RSV remain at low levels. Authorities will watch whether that sequence develops into the typical autumn-to-winter pattern and whether the final wave remains modest or grows more substantially.

For residents, the immediate situation is one of preparation rather than emergency. Anyone considering flu vaccination should check availability with a healthcare provider, particularly if they belong to a group at higher risk of severe illness. The FOPH will use surveillance data to refine its assessment as December approaches.