British variant already accounts for 30% of cases detected in Olot wastewater

Barcelona / GironaThe expansion across Catalonia of the variant of covid-19 identified in the United Kingdom is unstoppable. There are already regions such as the Garrotxa where the mutation represents a large part of the infections. The Department of Health has detailed this Wednesday that, until February 2, approximately 30% of the samples of wastewater analysed in the treatment plant of Olot corresponded to this variant. "This indicates the trend where the mutation is taking hold, which probably displaces the original because it is faster and more transmissible," explained Albert Bosch, professor of microbiology at the University of Barcelona and leader of a research team on enteric viruses.

According to the virologist, in Olot there is a higher proportion of the British variant than in other areas of Catalonia. By way of example, he has highlighted that the largest sewage treatment plant in Spain, the Besòs plant, where 525 million litres of sewage are processed per day and which serves millions of people, is identifying much fewer samples of the characteristic genome of the British mutation. In fact, about 15% of the samples correspond to the mutation, half as many as in Olot.

But the presence of the British variant has also increased in the wastewater treatment plants in other areas of the Girona area, specifically in Banyoles (Pla de l'Estany), where it could represent about half of the cases, and in the Gironès region, where it would represent one in four cases. Also in the Vallès Occidental (Rubí, Sabadell and Montcada i Reixac), in the Vallès Oriental (Granollers) and in the Baix Llobregat (El Prat, Martorell and Abrera) the incidence is rising.

Bosch has specified that, on the contrary, in the Lleida treatment plant, where the situation of Aran is of particular concern, the British variant has hardly been detected. It has been found in samples of infected people sent from this region to the Vall d'Hebron Hospital laboratory, which has revealed that between 5% and 6% of cases corresponded to the mutation mentioned.

Bosch's team has been analysing wastewater for months to detect traces of the coronavirus and assess the entry and implementation of the different variants in Catalonia. The presence of mutations, said the researcher, can be estimated and determined almost directly by sampling the sewage, where you have to look for the part of the genome that identifies each variant. These studies have found that on 22 December there was no trace of this mutation in wastewater and that it was not until 13 January that some cases appeared.

More sequencing

The four major Catalan hospitals (Clínic, Vall d'Hebron, Germans Trias i Pujol and Bellvitge) are sequencing many more samples of the virus to identify possible mutations and the head of the microbiology service of the Hospital del Vall d'Hebron, Tomàs Pumarola, has confirmed that the spread of the British variant was already a fact throughout Catalonia. If you look only at the results of clinical samples that these centers randomly process, its presence varies and is growing more in more densely populated.

The incidence ranges between 3% and 12%, and it is the southern metropolitan area of Barcelona that concentrates more cases of the British mutation (13%). The Bellvitge laboratory, which serves this area, has specified that between 25 and 31 January the British variant already accounted for 13% of all cases of covid-19 in the region, while in early January the figure was 4%. In Barcelona there are 9% of British variant and in the northern metropolitan area, between 7% and 8%.

"In the coming weeks we will see the proportion will increase more and more," said Pumarola, who has clarified that it was expected that this variant arrive in Catalonia due to its large presence in nearby countries. However, the projections are not positive for Catalonia, where it could change the downward trend in cases of the past weeks. The projections suggest 16,500 cases per week, 17% less than those diagnosed today. In the UK, for example, the growth curve was very slow and steady until the British mutation managed to cause 15% of infections. "Then it shot up and this is what could be expected in Catalonia," admitted Pumarola.

First case of the South African strain

As well as the threat of the British mutation, which has come to stay, we must add the South African variant, identified for the first time in Catalonia on Wednesday. The Secretary of Public Health, Josep Maria Argimon, has confirmed that this morning the variant has been detected in the city of Barcelona in one of the different samples that are randomly sequenced in the laboratories of the four major hospitals. The affected person has not travelled to Africa. "From the first data we have, he does not seem to have a clear relationship with South Africa," said Pumarola. He stressed that the case was under study, but admitted that the mutation was spreading and that "probably" there are more cases.

This first case detected in Catalonia is the second infection of the South African variant recorded in Spain and, moreover, the first that would have no relation to South Africa. The first case was detected a month ago in Galicia, specifically in Vigo, in someone who had visited the country. The British, South African and Brazilian variantes are more contagious than the original Wuhan virus. "We have to be prepared because all viruses mutate and this will make variants will appear and some come to displace the previous one," warned Bosch. Argimon admitted that the spread of new variants "is not good news" because they are transmitted more, although he stressed that they do not necessarily have to be more harmful.

More protected care homes

The Secretary of Public Health has pointed out that the incidence among the population living in care homes has fallen mainly for two reasons: the intensive screening of users and workers to detect and isolate positive as quickly as possible and because the percentage of people vaccinated in these environments is already very high: "90% of residents have received the first vaccine and, as we have said before, with this first dose, after twelve days, people start getting protection". Around 62% of the residents have already received the second dose and Argimon has assured: "We are in the process of achieving the protection of geriatric homes, where the most vulnerable people live"

In addition, in one month over 236,000 tests have been carried out and the positivity is 3.43% in residents and 0.75% in workers, a far cry from the 6.68% recorded in the general population. Also the Deputy Director General of Health Promotion, Carmen Cabezas, has remarked that people who are in residences have a lower rate of hospital admissions than the rest of the population thanks to vaccination.

The doctor stressed that if ten days ago we were detecting 1,280 cases among care home residents over 74, now the figure has fallen below half, with 576 active infections. "Ten days ago we had 55% more cases," he said. Also the number of centers that have a case or active outbreak has fallen by a third, from 237 nursing homes affected to the current 146. "We can already see that vaccination is having an effect on the health of the population," he insisted, and predicted that the total number of doses will be administered between next week and the following week.