Covid is gaining ground in Spain as autumn begins. SiVIRA figures for week 37 show infections and positive tests rising, along with mild hospital admissions. The increase has not brought a new wave of severe illness, but the virus is once again at the centre of respiratory surveillance.
The contrast with other seasonal viruses is clear. Influenza and Respiratory Syncytial Virus remain at low levels, while SARS-CoV-2 is already rising. The data point to an increase in Covid, not a wider surge in respiratory viruses.
Primary-care data show more acute respiratory infections compatible with Covid than in the previous week. Spain's ISCIII and its SiVIRA surveillance system recorded a Covid-19 syndrome rate of 11.3 per 100,000 in week 37, up from 8.0. Test positivity also rose, reaching 16.7%, compared with 15%.
Hospitals are seeing the same trend. More patients admitted with severe acute respiratory infections are testing positive for SARS-CoV-2. The share of admissions linked to the virus is rising too, though only gradually.
The hospital system is not seeing a comparable escalation. Among patients admitted with severe acute respiratory infection, the share testing positive for SARS-CoV-2 rose to 15% from 11.6%. Covid hospital incidence remained low, at about 1.2 per 100,000, although it was almost twice the previous week's level.
Healthcare pressure remains stable, and surveillance data show no sign that the disease is becoming more severe. The current pattern reflects wider circulation and increased detection, without a sudden worsening of the disease. For the public, closer monitoring is warranted, not alarm.
Virological surveillance has found no sign of a sharp variant replacement behind the rise. The circulating variants remain broadly stable, making seasonal and social conditions more likely drivers of the increase than a sudden change in the virus itself.
People are returning to workplaces and schools. Mobility has increased after the summer, and people are spending more time indoors. These changes create conditions for transmission to pick up.
This is not an isolated September episode. Since 2022, Spain has repeatedly recorded smaller waves as people return to their usual routines. Similar increases appeared in weeks 36 and 37 of 2023, followed by a short wave in early September 2024. The rise in 2025 was smaller but followed the same seasonal pattern. The 2026 episode again brings more infections and detections, with mild admissions also increasing, but has had no major impact on hospitals.
The current signal is epidemiological, not an emergency alert like the one described in earlier reporting. Its practical importance is that Covid has started rising while flu and RSV remain quiet. This gives health authorities more time to monitor the start of winter before several viruses begin circulating together. The European Centre for Disease Prevention and Control also included respiratory-virus developments in its week 38 report, placing Spain's September increase in a wider EU/EEA context.
ISCIII experts also point to increased social contact in enclosed spaces as a recurring factor. Warm temperatures have not stopped the autumn shift: people are returning to indoor routines even while summer conditions continue.
Some specialists are also reporting more cases of tonsillitis, particularly among children and working-age adults. That does not change the basic surveillance finding: Covid is currently driving the rise in respiratory viruses.
The risk is not evenly distributed. Older people face greater exposure to serious consequences, as do immunocompromised patients. Chronic conditions also raise the risk. Accumulated immunity from vaccination and previous infections still helps protect against severe disease, but it does not prevent reinfection.
The experts cited in the report are calling for stronger seasonal vaccination among vulnerable groups. They also support access to different vaccine platforms as the virus evolves.
Spain is entering the colder season with a familiar warning. Covid has not disappeared, and its first autumn rise has arrived before the usual influenza and RSV wave. Stable variants and limited hospital pressure make this a manageable development, not a crisis.
Ignoring the increase would still be a mistake. The evidence supports targeted vaccination and close surveillance, along with extra care for people whose age or health leaves them less able to withstand another infection. Reports on the seasonal campaign say vaccination against flu and Covid-19 is due to begin on 28 September 2026 in care homes and centres for people with disabilities; RSV vaccination is also planned where indicated.
