Surveillance trends of the 2009 influenza A(H1N1) pandemic in Europe

Contribution of the Portuguese Laboratory Network for the Diagnosis of Influenza A(H1N1)pdm09 Infection during the 2009/10 and 2010/11 influenza seasons

“…Regarding the pattern of disease, the data collected through the Laboratory Network support the data obtained from the National Influenza Surveillance Programme [7] and suggest that the 2009/10 pandemic was similar to the previous influenza season in intensity and geographical distribution. Seasonal viruses were replaced by the new influenza A(H1N1)pdm09 strain, which caused disease particularly in young children, consistent with the data from all European countries where children under the age of 14 years were affected the most [5].…”

“…A very similar pattern was observed in Spain and other European countries [5,17]. In Portugal the pandemic influenza A(H1N1)pdm09 virus was first detected on 4 May, soon after the first case confirmed in Spain (27 April 2009) and in Europe (13 April 2009).…”

“…In Portugal the pandemic influenza A(H1N1)pdm09 virus was first detected on 4 May, soon after the first case confirmed in Spain (27 April 2009) and in Europe (13 April 2009). Data from Spain and combined data for Europe show the first peak of influenza cases in 2009 during weeks 31 and 30, and the second peak during weeks 47 and 46, respectively [5,17]. The 2009 pandemic was considered a mild one for Europe, with little impact on services outside the health sector [5].…”

“…Following the detection of the initial imported cases, there was a spring and summer wave of transmission which affected several European countries. Transmission accelerated again after the re-opening of schools, this time affecting all countries, and lead to an early autumn/winter wave [5].…”

Réunion, a sentinel territory for influenza surveillance in Europe

“…In 2010, a weaker epidemic was observed with also a non-negligible number of severe cases [15]. Similar patterns were then observed in Europe [16], confirming that surveillance of influenza in Réunion can also provide useful data to anticipate what can be expected a few months later in northern hemisphere countries in terms of dynamics, severity and circulating viruses. During the last three years, our epidemiological data identified obesity and diabetes as risks factors of severe form of influenza.…”