Mobility outside the region, a litmus test for the pandemic

Santa Coloma de Gramenet"The epidemiological situation is not good, we have a thousand cases a day, which is a lot for the system, but we are not at the peak of a new wave. Now we can do more things than a few weeks ago after three months of sacrifices, but always in a responsible way", diagnoses the physicist and researcher of the Computational Biology and Complex Systems Group (Biocom- SC) of the UPC, Clara Prats. And within this desired and prudent behavior she highlights responsible mobility only with the cohabitation bubble, and, in case meetings with someone from another group areheld, they should be outdoors, with a mask and without undergoing risky activities, such as meals and overnight stays.

The Government foresees that 930,000 vehicles will move on Friday from the metropolitan area of Barcelona taking advantage of the fact that it is the first weekend without regional lockdown for cohabitation bubbles. Bookings of holiday homes and the sales of ski passes have shot up in spite of the bad meteorological forecasts, which is why the sanitary authorities ask the population to be very diligent and prudent.

Extreme caution is not a request that can be taken lightly: the Catalan epidemiological situation is unstable and the shake-up of the indicators that has occurred in recent days could precede an increase in infections. It will depend on the population, Prats insists, whether this growth will be unbridled and cause a fourth wave or whether it will be a controllable increase, within the normality of the easing of restrictions.

"If a small part of the population generates a few secondary cases, because it is infected and does not reduce social interaction, but increases it this weekend, the next few days transmission will grow and we will be at risk of suffering a fourth wave", warns the epidemiologist and president of the Tuberculosis Research Unit of Barcelona (UiTB), Joan Caylà.

The message from the experts is clear: this weekend can contribute to destabilise the epidemiological situation in Catalonia and we must be more careful than ever. The rise of the curve is very easily triggered and in a matter of days it can do much damage, says Caylà. On the other hand, experience shows that turning it back is not so easy. A false step spoils the work and the milestones achieved after many weeks and great social, economic and emotional sacrifices.

Currently, the Alt Pirineu and Aran is the region with the highest cumulative incidence of fourteen days, with 402 cases per 100,000 inhabitants, but also the one that is expected to receive more visitors this weekend and, according to tourist reservations, all Easter. In Cerdanya, for example, hoteliers expect to exceed 50% occupancy between now and Sunday, figures similar to those of a winter weekend before the pandemic.

"People want to go out, it's normal, but we have to be aware that it is not appropriate to go with friends to the beach or the mountains and you can not hold meetings without a mask", explains Caylà, who insists on the importance of moving only with the same bubble and following all the recommendations. "Surely 90% of the population will do well, but 10% complicates everything for us. Reopenings only work when everyone complies 100% and this doesn't happen".

Changes in the curve

The decline in the contagion curve has slowed and Prats doubts whether the stagnation of the indicators will be temporary, as happened three weeks ago, or if it is the sign of a new increase. "With the context of more mobility and Easter coming up close, it is unlikely that we will resume a sustained decline as we have experienced so far", she admits. When the curve slows down, three things can happen: it can go down again -although it is unlikely-, stay at the same values or go up. "It looks like we will have a new growth, but we hope it will be gentle and that we can control it quickly".

The infection rate, or R number, which measures the speed at which the virus spreads, is already above the threshold of 1 and the pandemic has therefore entered the expansion phase. Once again, each positive person infects another person - the chains of transmission are not being cut sufficiently - and there are more infections, more transmission and more risk of epidemic decontrol. The optimal situation would require this figure to be between 0.5 and 0.8. In addition, the fact that hospitals are still very full - there are 1,427 admitted and 406 critical patients - further aggravates the scenario of the coming weeks: the Health Department warns that a fourth wave would now fill the intensive care units (ICU) with 800 patients.

The other indicators remain fairly stable, such as the EPG and the positivity rate, which remains below the 5% set by the World Health Organization (WHO). "Every week that we can beat the fourth wave we will have fewer deaths. With the vaccines, moreover, we will soon see a reduction in mortality and serious cases, because there is more fragile population protected", explains the biophysicist, who stresses that in the event of a fourth wave it would not affect care homes. The problem, says Prat, is that those over 80 years old are not yet fully protected and could become seriously ill and die. And hospitals will again receive an avalanche of patients between 50 and 70 years, which are those who really occupy the ICU. What happens these days, as always, will mark the immediate future of the country.