Decreasing trend in influenza epidemic activity but increased incidence

Influenza epidemic activity is on a declining trend in Portugal, according to the Instituto Nacional Doutor Ricardo Jorge (INSA), despite an increase in the incidence of influenza syndrome to 34.6 per 100,000 inhabitants.

Influenza Epidemiological Surveillance Bulletin 2-8. according to may (week 18), the incidence of acute respiratory infections (ARI) followed an increase and also rose to 34.6 per 100,000 population (previous week: 8.0).

According to the INSA, two cases of influenza (influenza A) were reported during the week analyzed by 17 intensive care units (ICUs). One patient was 75-84 years old and the other was 35-44 years old. One of the cases had comorbidities and he had been vaccinated against seasonal flu.

Since the beginning of the season, 28 cases of influenza have been reported in the surveillance departments, all due to the influenza A virus.

19 cases of influenza were reported from the reporting departments and influenza A virus was identified in all cases.

In the period 2021/2022, laboratories in the Portuguese network of influenza diagnosis laboratories (hospitals) reported 102,350 respiratory infections and 6,599 cases of influenza.

Between 2 and 8 May, according to the press release, 357 positive cases of influenza virus were detected, of which 356 were type A and 1 was type B.

To date, 141 cases of co-infection with influenza virus and SARSCoV-2 have been reported.

In the release, INSA also states that since the beginning of the 2021/2022 season, other respiratory agents have been identified in 5,335 cases. In week 18/2022, 172 cases were detected.

A total of 204 influenza viruses were characterized by week 18 (May 2-8), all of which had antigenic properties different from those contained in the 2021/2022 influenza vaccine.

Influenza vaccinations were started in Portugal at the end of September, earlier than usual due to the covid-19 pandemic, and more than 2.5 million people were vaccinated.

The INSA also mentions that mortality for all causes is “within this season’s expectations”.

Regarding the situation in Europe, INSA reports that in week 17 (April 25-May 1), the laboratory detection rate of influenza virus in several countries in central and western Europe was over 30%: in Finland (80%), in the Netherlands. (60%), Poland (50%), Serbia (38%) and France (33%).

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