Portugal: Covid-19 incidence up again, transmissibility index down

The incidence of infection with the SARS-CoV-2 coronavirus in mainland Portugal continues to rise, standing on Friday at 138.7 cases per 100,000 inhabitants, as well as for the whole country, which is now 137.5, official data shows.

The incidence of infection with the SARS-CoV-2 coronavirus in mainland Portugal on Wednesday was 129.6 cases per 100,000 inhabitants, while the figure for the whole country was 128.6.

According to the joint epidemiological bulletin of the country’s national health authority, the DGS, and the National Institute of Health Doutor Ricardo Jorge (INSA), the transmissibility index (Rt) decreased from 1.17 to 1.14 throughout the country and from 1.18 to 1.15 in mainland Portugal.

The transmissibility index and 14-day incidence data are updated on Mondays, Wednesdays and Fridays.

These indicators – the transmissibility index of the virus and the incidence rate of new cases of Covid-19 – are the two criteria defined by the government to evaluate the relieving of lockdown measures process that began on 15 March.

INSA. Algarve is the region with highest transmissibility index

The Algarve region has the highest transmissibility index (Rt) of the SARS-CoV-2 virus in the country, with 1.3, while in Lisbon and Tagus Valley it has fallen to 1.11 according to data released on Friday by INSA.

At the national level, from 14 June until Sunday, there was a reduction of the Rt from 1,20 to 1,1, which was also registered in the Lisbon and Tagus Valley region, where it went from 1,26 to 1,11, according to the weekly report of the epidemic curve of the National Institute of Health Doutor Ricardo Jorge (INSA).

For INSA researchers, this result suggests a deceleration in the increase in the number of new cases in this period, that is, the number of new cases continues to grow, but more slowly.

On the other hand, in the Algarve region there is a sharp increase in the transmissibility index, having gone from 1.07 on 27 May to 1.4 on 14 June (0.33 in 19 days).

“From this date onwards, the Rt decreased to 1.3 on 19 June, remaining, however, still high,” INSA pointed out

This situation report aims 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).

After correcting the epidemic curve for the delay of notification, based on the data collected, INSA estimates that by last Sunday there were 869,663 cases.

According to researchers, the average Rt figure for the days from 16 to 20 June was 1.14, and its true value could be between 1.13 and 1.15 with a confidence level of 95%.

The following R(t) values were also estimated for the regions: 1.03 in the Northern region, 1.12 in the Centre region, 1.17 in the LVT region, 1.08 in the Alentejo region, 1.34 in the Algarve region, 0.98 in the Azores and 1.17 in Madeira.

“All regions have an average transmissibility index (five days) greater than 1 except the Azores,” said the researchers.

Portugal has a 14-day cumulative reporting rate between 120 and 239.9 per 100,000 inhabitants and R(t) greater than 1, i.e. a high reporting rate and with an increasing trend, they added.