Flu season is already in full swing. According to data from the Italian National Institute of Health's RespiVirNet surveillance system, in the last week, 585,000 Italians were hospitalized due to respiratory infections, including influenza. This represents 10.4 cases per 1,000 citizens, an increase of approximately 11% compared to the previous week, when the figure was 8.96 cases per 1,000. This brings the estimated number of infections since the start of the season to 3.3 million.
Children under 4 continue to be the most affected, with an incidence three times higher than the average : 33 cases per 1,000; in the 5-14 age group, the rate is 13 per 1,000; 10.9 in the 15-24 age group; 11.5 in the 25-44 age group; 9.5 in the 45-64 age group; and 5.5 cases per 1,000 among the over-65s.
Among the Regions, the highest incidence (13.08 cases per 1,000) was observed in Sardinia, followed by Campania (11.96) and Lombardy (11.66).
All regions, however, are recording low levels of infection, and in four (Liguria, Molise, the province of Trento, and Umbria) the season has practically not started, with cases at baseline. Currently, the trend is "as expected for the period," the ISS reports.
However, the presence of influenza viruses is increasing, which are responsible for a growing number of infections. In particular, last week, of the 2,088 samples analyzed by laboratories belonging to the ISS surveillance network, 20.3% (423) tested positive for influenza viruses, almost all of them type A.
Among these, the percentage of A/H3N2 viruses is steadily increasing, significantly outnumbering A/H1N1 viruses. The presence of Covid-19 is low: only 83 samples (4%) tested positive for SarsCoV-2; 51 (2%) tested positive for Respiratory Syncytial Virus. Among the other respiratory viruses, the most common were Rhinovirus and Parainfluenza viruses.
There are no reports of avian influenza cases in humans. Meanwhile, growing concern is growing over the spread of a variant of the common influenza virus, characterized by a genetic mutation (S247N of neuramidase) that makes the antiviral drug oseltamivir less effective.
A study coordinated by the Vall d'Hebron research institute in Barcelona and published in the journal of the European Centre for Disease Prevention and Control (ECDC) showed that in Catalonia, 11.8% of A/H1N1 influenza samples analyzed since the beginning of the season possess this mutation, which has been known for fifteen years but had previously been very rare. A similar trend was observed in France, the Netherlands, Norway, Denmark, and Belgium, and overall, 2.2% of European A/H1N1 sequences possess the mutation.
When combined with other mutations, this alteration can render the virus completely resistant to antivirals. Therefore, "strengthened surveillance of the evolution of these H1N1 influenza virus strains is urgently needed," the researchers say.
(Unioneonline)
