A huge chunk of the Covid-19 cases in Europe this summer came from a newly identified variant of the coronavirus that first emerged in a super-spreading event among farmworkers in Spain, according to a new preprint report. While a number of factors might explain the prevalence of this variant, the researchers argue that its spread is most likely linked to the large number of tourists who traveled around Europe during their summer vacation.
Scientists at the University of Basel, ETH Zürich in Switzerland, and the SeqCOVID-Spain consortium reached these findings by comparing the virus genome sequences collected from Covid-19 patients across Europe. Their findings — which have not yet been peer-reviewed — can be read on the preprint server medRxiv.
Their research revealed that the newly identified variant — named 20A.EU1 — remains one of the most prevalent variants in Europe. It currently accounts for around 90 percent of the studied sequences from the UK, 60 percent of sequences from Ireland, and between 30 and 40 percent of sequences in Switzerland and the Netherlands. It’s also been identified in France, Belgium, Germany, Italy, Latvia, Norway, and Sweden, as well as further afield in Hong Kong and New Zealand.
20A.EU1 appears to have originated in Spain this summer, with the earliest evidence of the variant being linked to a super-spreading event that occurred among agricultural workers in northeastern Spain. It then moved into the local population, where it was able to travel to the Valencia Region and on to the rest of the country. Once Spain reopened its borders in June, the variant started to pop up in several different European countries.
“One variant, aided by an initial super-spreading event, can quickly become prevalent across the country," Professor Iñaki Comas, co-author on the paper and head of the SeqCOVID-Spain consortium, said in a statement.
Although there is currently no evidence to suggest that this variant is any more contagious than others, it has clearly managed to spread far and wide across the European continent. The researchers argue that it most likely became seeded across many countries through tourism, with genetic analysis suggesting that dozens or perhaps hundreds of people were taking the virus out of Spain and across Europe. As such, they believe that the spread of 20A.EU1 shows governments need to take a serious look at how to manage their borders and travel policies during the ongoing pandemic.
“Long-term border closures and severe travel restrictions aren’t feasible or desirable, but from the spread of 20A.EU1 it seems clear that the measures in place were often not sufficient to stop onward transmission of introduced variants this summer,” explained Dr Emma Hodcroft, lead author of the study from the University of Basel.
“When countries have worked hard to get SARS-CoV-2 cases down to low numbers, identifying better ways to ‘open up’ without risking a rise in cases is critical.”
A separate study from across the Atlantic has also investigated the spread of Covid-19 in Houston, Texas, by looking at different variants of the virus. As reported in the journal mBIO, they found that up to 71 percent of patients with Covid-19 had a specific variant of the virus during the initial wave of the outbreak. Once the second wave hit, that proportion skyrocketed to up to 99.9 percent prevalence. In this instance, the researchers think that the Houston variant underwent a natural mutation that occurred on the viruses’ spike protein, perhaps making the pathogen more contagious.
There is no evidence to suggest a similar thing occurred with the 20A.EU1 variant in Europe. However, both of the studies highlight different factors that can help certain variants of SARS-CoV-2 take hold and spread through a population.