It is difficult to know the exact origin of the second wave of COVID-19 that we have been facing since September. While it is almost certain that the virus continued to spread silently this summer, especially ‘invisibly’ via the younger generation, we do not really know which strain of the virus is now most active, nor how it emerged. Scientists have provided answers to these questions in a recent study.A variant that comes from the north-east of SpainSwiss and Spanish researchers shared their findings on MedRxiv on October 29th. They explained that they had found a variant of SARS-CoV-2, called 20A EU.1. By studying it, they revealed that they had identified the first cases in June in the region of Aragon, in north-eastern Spain.Farmworkers were contaminated there in June, who then allowed the virus to spread, first among the local population and then throughout the country and Europe via holidaymakers, who were sometimes not very conscientious when it came to social distancing. These are the oldest detected traces of the virus, but it is likely that it appeared much earlier.A strain that has become the majority in EuropeSince June, this variation of SARS-CoV-2 has become widespread, so much so that it is now the most common mutation of the virus in Europe. In Spain, it is present in 80% of cases, as in the UK. In Ireland, it is also high as it can be found in 60% of cases. In France, it is present in 40% of cases. 20A EU.1 now accounts for more than 70% of all sequences analysed by researchers. They have even identified the presence of this variation in New Zealand and Hong Kong. Is this strain deadlier than the original? According to Emma Hodcroft, lead author of the study, this is difficult to prove. ‘We have no evidence that this mutation increases transmission or influences clinical outcomes,’ she concedes, explaining that she ‘has never seen a variant with such powerful dynamics’ since she began her studies. This is a discovery that highlights the importance of controlling borders during a pandemic, but also of respecting social distancing.