School closures, which led to less mobility, and the more restrictive measures imposed by the Government helped a faster drop in the transfer rate, show estimates from the Covid19 Insights project

The closure of schools, and the consequent decrease in mobility, and the more restrictive measures imposed by the Government from mid-January helped a faster drop in the transmissibility rate of the SARS-CoV-2 virus, making the effect of the current confinement very close to the effect achieved with the confinement made in March and April last year. Within a week it was possible to reduce the transmissibility of the virus by 35% to 40%. It is still early to relax, but this greater compliance with the measures is beginning to reveal some impact on the covid-19 numbers. Although hospitalizations and deaths remain high.

“To evaluate a containment, what matters is to measure its effect. The effectiveness of a confinement is seen by the drop in the rate of transmissibility. This rate is the product of two elements: contact rate – mainly represented by mobility – and the likelihood of transmission – represented by the characteristics of the virus and the protective barriers we use ”, explains to PUBLIC Pedro Simões Coelho, coordinator of the Covid19 Insights project, an initiative by NOVA IMS and COTEC.

To measure the effect of the current confinement, the reference was the average speed of the drop in transmissibility of the virus in March and April last year. “We estimate that at the beginning of this confinement, this reduction in the transmissibility of the virus took place at a speed that would be 30% of the speed that was made in March and April. In other words, it was 30% of the effect achieved in the first confinement”, says the specialist, referring to a period that goes from the second week of January to the closing of schools. From that date on, “this effect began and has been progressively intensified and at that date we estimate that the effect of this confinement is about 90% of that of March / April “.

What has changed to achieve this result, even though since the beginning of January there has already been some reduction in the mobility that people have assumed, anticipating the confinement decreed by the Government? “Until January 17th, the presence in workplaces was still very strong. There was already some drop compared to the reference level – average mobility in January and February 2020, when there was still no pandemic – from -11% to -26%, but now the drop is more than 40% ”, begins by explaining .

It is this change that now allows for more favorable estimates than those obtained two weeks ago. Thus, the peak of prevalence is expected to happen these days, with about 182 thousand active cases. This figure should drop to 160 thousand on 7 February. Also for that day, the scenarios point to the existence of 5900 people with hospitalized covid, of which 825 are in intensive care units. The maximum number of hospitalizations will have been reached on day 1 and the maximum in intensive care is likely to happen by the end of the week. As for deaths, the maximum will have been reached on 30 January with about 300 deaths per day.

But the country is still far from breathing relief, even though the Rt (transmission risk) is slightly below 1. According to estimates, this should only drop below 0.8 in the second half of this month and it will be for that reason that the security barrier of 5000 new daily cases should be reached. “The value of 50 new cases per 100 thousand inhabitants has been used by many as a barrier below which it is possible to have an adequate traceability of the cases and to make an identification of the transmission chains. And, consequently, we have to do this as soon as possible”, states Pedro Simões Coelho.

The president of the Scientific Council of NOVA IMS also points out that the estimated number of hospitalizations, especially in intensive care, shows how the National Health Service (SNS) is close to its maximum capacity, since the same criteria of previous phases were used of the pandemic, estimates would point to higher numbers of patients hospitalized at around 200 in intensive care.

“This is one of the reasons why confinement needs to be continued in this severe way for some time. It is essential to maintain or intensify [the drop in transmissibility] for some time to avoid this situation of rupture and try to prevent this excess mortality from continuing ”, he reinforces, stating that if there is capacity to control transmission chains and lower numbers it will be possible to progressively suspect. But always evaluating this impact so that a new growth of contagions can be stopped.