Catalonia keeps virus at bay ten days before Christmas, but indicators are very fragile

Santa Coloma de GramenetThe apparent improvement in epidemiological indicators over the past week leaves no room for error. The fragility of the epidemic, which is very sensitive to changes in behaviour and population mobility, as well as to screening policies, makes it impossible to speak of stabilisation, as the health authorities pointed out on Monday. Although some bending of the curve is appreciated, the effect of the past bank holiday, the crowds of people, and the increase in mobility that has been recorded is not yet reflected in the data. Therefore, Catalonia is keeping back the virus but advances very slowly, as there are little more than ten days to go for Christmas.

The reopening of economic sectors and the increase in social interaction associated with it have triggered one of the key indicators for controlling the epidemic, the rate of infection (Rt). Its growth by almost twenty hundredths in a matter of four days set off the alarms of the Catalan Government, which chose to slow down the progress of the reopening when the green light had only been given ten days earlier. Two weeks later, the fluctuations of the R have been straightening out and, despite its constant threat, contagion has not multiplied. On the contrary, the slope of all indicators is downwards.

Catalonia has almost achieved the goal set by the government of reducing daily infections to a thousand - now around 1,100 cases are reported every day -, and this is because the R, which indicates how many people on average each infected person infects, remains below 1. "What has to be made very clear is that the indicator that fluctuates is the R and while it is below 1 there will be fewer cases. As a measure of how fast new cases are falling, the farther away from 1, the faster they will fall; the closer to 1, the slower they will fall. And if the threshold of 1 is crossed, they will increase", explains the researcher from the Computational Biology and Complex Systems Group at the UPC, Clara Prats.

In terms of infections, then, Catalonia has achieved figures similar to those of September and October, just before the second wave. However, the situation is not comparable in the healthcare data, which is too high: there are 1,436 admissions for coronavirus, 345 of which are in intensive care beds. "We can't be left alone with the epidemiological data: the ICUs are emptying very slowly," warns Prats, who points out that by Christmas the occupation will not have been reduced enough to lower the guard. "When the second wave started we had about 150 admissions and, despite the measures, we almost exceeded the threshold of 600 occupied ICU beds. Now, we have 345 critically ill", Prats says, "if the pattern is repeated, the growth will be much faster because we have a thousand cases a day and many contagious people. And, therefore, there would be no margin for reaction to avoid the collapse of the health system.

Sudden increase in R due to the bank holiday

Prats anticipates that the influence of the bank holiday on the contagion curve will only be seen next week, but warns that the R will drop for a few days, because it has not been diagnosed enough, and will suddenly rise again. According to the expert, the infection rate reflects the most abrupt ups and downs, and therefore allows for the detection of possible changes in trend a little in advance. "If it shoots up, you have to look for what factors are behind it: maybe they are cases that come because of the weekend's delay, or because of social interaction and, as a consequence, transmission increases", Prats explains. This combination is precisely what happened two weeks ago - the R warned that the plan to ease restrictions had to be stopped. "Two weeks ago the services had been reopened and massive screening was being done again, which increased the diagnoses quite a lot. With all this, the Rt issued a warning signal: we could not move forward with the easing of restrictions", Prats says. We will have to see if this jolt is repeated next week because of the bank holiday.

Now, however, the expert assures that the data only reflects the effect of the reopening and that is why the rise in the indicator, despite being very close to 1, is softer. "And these figures, around 0.94 and 0.97, are within what we expected", admits Prats. In the last fourteen days 210 infections of covid-19 per 100,000 inhabitants have been diagnosed, almost half of what was detected just a month ago. But the figure is still far from the recommended threshold (50 cases per 100,000 population). The good news is that the positivity of the tests being done has fallen below 4%, while two weeks ago it was 6%, and some 50,000 fewer diagnostic tests were being done.

An outbreak with 54 positive cases detected in a geriatric hospital in Cambrils

The coronavirus keeps retirement homes in all Catalonia alert. Yesterday, the Health Department reported an outbreak at the STS retirement home in Cambrils (Baix Camp), where 42 residents and 12 workers have been diagnosed as covid-positive by a routine screening of the nursing staff. According to the ministry, the situation is under control and all those affected are either asymptomatic or have very mild symptoms.

Also in the Camp de Tarragona, the Pius Hospital from Valls reported yesteray an active outbreak affecting 26 people - 21 health professionals and five patients -, the origin of which is believed to be the companion of an asymptomatic patient. For now, however, and despite restricting visitors, the hospital is functioning in a normal manner.