Adolescents and young adults They have become the groups that register the most cases of coronavirus infection in Catalonia, a phenomenon that is explained by the high mobility and social interaction of these age groups.
But while schools are able to detect the vast majority of infections and stop outbreaks, from the age of 18 it becomes more difficult to trace the contacts of positive cases. This makes a significant proportion of infections in young adults go undiagnosed, as can be deduced from the data on the distribution of cases by age group to which they have had access The vanguard.
Undiagnosed people, unaware that they have the Covid-19 virus, can transmit the infection to others without knowing it. Hence, one of the main measures proposed by the Department of Health in Catalonia to contain the epidemic is the cancellation of face-to-face classes in universities for two weeks.
With this it is expected reduce mobility and social interaction, and therefore contagion, in a group in which the epidemic is now out of control.
In both the 10-19 age group and the 20-29 age group, some 200 new cases per 100,000 inhabitants in the week of October 2 to 8.
This rate is higher than the average for Catalonia, which stands at 129.5 cases per 100,000 inhabitants in the same seven days. And multiply by four the 50 weekly cases that Germany considers the limit from which to enter restrictions to mobility and social interaction.
But there is an important difference between the two age groups. The 10-19 year old is the group they are doing more tests diagnostic by PCR. There have been 4,143 PCRs per 100,000 inhabitants between October 2 and 8 in this group (or, what is the same, one in 24 people have had a diagnostic test this week).
In the 20-29 age range less than half have been done PCR in the same period: 1,904 per 100,000 inhabitants.
As a consequence of the greater diagnostic effort in the school population, less than 5% of PCRs give a positive result in the population aged 10-19 years.
This indicates that the vast majority of cases of coronavirus infection are detected among adolescents (since, to detect a majority of cases in people who do not always have symptoms, it is necessary to do many tests assuming that many will be negative; it is estimated that, if the percentage of positives exceeds 5%, an important part of cases remains undetected).
On the contrary, in the population aged 20-29 years the percentage of positives exceeds 10%. Therefore, the number of actual cases has to be significantly highest than the number of diagnosed cases.
And the incidence of 195 weekly cases per 100,000 inhabitants that has been registered underestimates the real incidence, which has to far exceed 200.
Schools are not a source of contagion
“The 20-29 strip is what more worries me”, Acknowledged on Sunday Josep Maria Argimon, Secretary of Public Health of the Generalitat, in the interview in the Via Lliure program of RAC1 in which he proposed canceling face-to-face classes at universities for 15 days. It is the age group “that has more social interaction, a higher incidence and at which it costs us more to get there”.
Argimon said he was also concerned about the 30-39 and 40-49 age ranges, the next with the highest incidences of coronavirus infection. In these groups, the percentages of positive CRP are also around 10%, which reveals that many cases they fail to identify themselves.
On a positive note, the age group with the lowest increase in cases in Catalonia is 0 to 9 years old. In addition, it is the one that best detects cases, with a percentage of positive CRP less than 4%, figures that confirm that schools are not sources of contagion.
At the other extreme, the contagions are in rapid rise in the age groups older than 70 years, which are those with the highest risk of suffering serious complications from Covid-19. Among those over 90, the incidence already exceeds 100 weekly cases per 100,000 inhabitants.
By Josep Corbella, Barcelona