Respiratory infections declining, but activity remains very high in two regions

National incidence shows a downward trend
The incidence of acute respiratory infections (ARI) in the community has fallen to 11.3 cases per 1,000 registered patients in the week from 19 to 25 January, down from 12.7 per 1,000 in the previous week. The data come from the latest report of RespiVirNet, released on 30 January 2026 and now available in an interactive format. Despite the overall decline, circulation remains significant, confirming that the seasonal respiratory wave is easing but not yet over.

Estimated cases and age-group differences
During the same week, surveillance systems estimated around 621,000 new cases, bringing the cumulative total since the start of seasonal monitoring to approximately 9.8 million infections. The reduction in incidence affected all age groups except children aged 0–4 years, where rates increased to about 40 cases per 1,000 patients, compared with 33 per 1,000 in the previous week. This pattern highlights the continued vulnerability of younger children, who often experience higher exposure and transmission in community settings.

Regional distribution and intensity levels
From a geographical perspective, incidence intensity remains very high in Basilicata and Campania. Medium levels are reported in Molise, Apulia and Sardinia, while low activity characterizes all other regions and autonomous provinces. In Liguria, incidence has returned to baseline levels. The report also notes that the recent transition from the traditional influenza-like illness (ILI) definition to the broader acute respiratory infection (ARI) case definition complicates direct comparisons with previous seasons and historical intensity thresholds.

Influenza positivity and severe cases
Regarding influenza circulation, in week 2026-04 the positivity rate stood at 26.6% in the community and 24.3% in the hospital-based surveillance flow. Monitoring of severe and complicated cases shows a decline in week 03 (12–18 January) compared with the same period of the previous season. Among severe cases, the most frequently identified subtype is A(H1N1)pdm09, and the majority of affected patients are reported as unvaccinated, underlining the persistent role of vaccination gaps in disease severity.

Virological patterns and circulating strains
Virological surveillance indicates that, in community samples, A(H3N2) viruses are more prevalent than A(H1N1)pdm09, while in hospital settings there is a slight predominance of A(H1N1)pdm09. Importantly, no samples of non-seasonal, non-subtypable influenza A viruses were detected, excluding—at present—signals of avian influenza circulation in humans. Sequencing analyses show that A(H3N2) viruses mainly belong to subclade K within clade 2a.3a.1, whereas most A(H1N1)pdm09 strains cluster in subclade D.3.1.1.

Implications for surveillance and prevention
The current RespiVirNet findings confirm a general decline in respiratory infections, while also pointing to persistent regional and age-related heterogeneity. Continued surveillance remains essential to track viral evolution, protect vulnerable groups—particularly young children—and guide vaccination and prevention strategies as the season progresses.

Prof. Foad Aodi