The INSA report analyses "the evolution of the number of covid-19 cases in Portugal" which indicates that the average value of Rt - which estimates the number of secondary cases of infection resulting from each person carrying the virus - fell from 1.06 to 0.98 at national level, between 26 and 30 September, and its true value could be between 0.98 and 0.99 with a confidence of 95%.
According to the report, the transmissibility index fell in all regions of the country compared to the previous week, estimating a Rt of 0.93 in the North region and 0.96 in the Centre region.
In the remaining regions of the country, this indicator is above the threshold of 1, reaching the highest values in the Azores (1.24) and Madeira (1.23).
In the Lisbon and Tagus Valley region, the estimated value of the Rt is 1.02, in the Alentejo region it is 1.06 and in the Algarve region 1.07.
"In the European comparison, Portugal presents the accumulated 14-day notification rate between 240 and 479.9 cases per 100,000 inhabitants and a Rt below 1, that is a high notification rate and with a decreasing trend," INSA states, noting that "only Portugal is in this situation".
Of the countries analysed, Belgium, Bulgaria, Croatia, Greece, Iceland, Norway, Poland and Slovakia show a downward trend in the number of new cases, with a transmissibility index below 1.
INSA estimates that since 2 March 2020, when the first cases were notified, up until 30 September, Portugal has registered a total of 5,500,200 infections by the virus that causes covid-19.
The purpose of this weekly report is to present estimates of the epidemic curve of SARS-CoV-2 infection by date of onset of symptoms and estimates of the transmissibility parameters R0 (basic reproduction number) and Rt (effective reproduction number as a function of time).