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- IAS® flu-like syndrome
The purpose of the IAS indicator (IAS®) "Flu-like syndrome" is to contribute to the monitoring of flu-like syndromes in France by providing additional information to that provided by Sentinelles and Grog networks.
IAS® Flu-like syndrome model is based on the tracking of a prescribed medicines selection with are delivered by pharmacies to cure seasonal flu. This indicator uses analytical methods and innovative visual representations processed by OpenHealth. On a national level, cross correlation with the Sentinelles network is high.
The IAS® is calculated every day using a temporal smoothing method: information for the previous seven days and the next 7 days are taken into account to calculate the value for a given day.
As announced by OpenHealth on January 11, the peak of the flu incidences season has been reached as early as of 3 January 2017. However, a long tray was observed until the end of January. The 2016-2017 epidemic was therefore more marked at the national level by this particular dynamic than by its intensity, which was average even though the excess mortality in the winter was high. At the regional level, the situation is mixed, with a southeast quarter where the epidemic peaked at the beginning of January (former Rhône-Alpes, PACA and Franche-Comté regions), while in the south-west (Aquitaine and Poitou-Charentes) the peak was also frank but at the end of January. It would be interesting to understand the cause of this interregional variability and to determine whether the same phenomenon is observed for winter excess mortality.
At the start of November, incidences of flu are still very low (2.7 cases per 100,000 inhabitants)
As with previous years, a slight peak was observed in early October with a maximum of 5.5 cases per 100,000 inhabitants on 12 October. With November and December, we are entering the period conducive to the development of seasonal flu epidemics. The Advanced Health Indicator, updated twice a day, is available to the public and the authorities to detect the start of an epidemic at the earliest opportunity.
After what looked like a second epidemic wave early March, especially in the West of France, the seasonal flu epidemic seems to be behind us. On a national level, the peak took place on Saturday 19th March. With an index of 164, the incidence peak had nothing to do with that of the 2014-2015 season, then it reached 1082.
The winter epidemic seemed to have reached its peak on 21st February. However, there has been an increase in incidences of flu since Wednesday 2nd March. The curve would indicate what may become a second epidemic during the same season. This winter’s very particular weather conditions (very mild then a late cold spell) may be behind this phenomenon.
The seasonal flu epidemic’s peak was reached on Sunday 21st February at the national level
This date is inside the range announced by OpenHealth on 27th January (between 18th and 25th February). The peak will have been earlier in the first regions to be impacted: 31st January in what used to be Basse-Normandie, 2nd February in Brittany. The 2015-2016 epidemic will have been much less intense than last year’s which had caused a significant increase in mortality. This swinging from high and low intensity years is a phenomenon that has been observed regularly and is probably due to the persistence of immunity in the population following massive epidemics.
In 2014-2015, the seasonal flu epidemic was very strong and peaked around the 7th February
This year the epidemic seems to be arriving later and will very probably be weaker. Even though the number of cases remains quite low, there has been a regularly increasing trend since the beginning of January. This epidemic seems to be starting in the west of the country (Brittany, Pays-de-la-Loire and Basse-Normandie) where there are about 10 times more cases than elsewhere in France. The peak of the epidemic should occur between the 18th and 25th February.
On 30th November, incidences of flu are still very low (3.1 cases per 100,000 inhabitants).
As with previous years, a slight peak was observed at the end of September with a maximum of 4 cases per 100,000 inhabitants on 24th September. In December, we are entering the period conducive to the development of seasonal flu epidemics. The Advanced Health Indicator, updated twice a day, is available to the public and the authorities to detect the start of an epidemic at the earliest opportunity. Whereas the Winter epidemic seemed to have reached its peak on 21 February, the incidence of flu is on the increase since Wednesday 2 March. The curve shows what could be a second epidemic wave over the same season. The very specific meteorological conditions of this Winter (very mild followed by delayed cold) are perhaps the reason for this phenomenon.