The NICD says the Beta variant appeared in 70% of all samples taken from coronavirus tests in May. But in June, it dropped to 39% while the Delta variant rose to 45%. Data from the UK shows that the Delta variant (first detected in India) is 97% more transmissible than the original lineage. Covid-19 vaccines remain highly effective in preventing severe disease after Delta variant infection, with the Pfizer-BioNTech vaccine showing 96% efficacy after 2 doses.