More than 4.4 million Covid cases and 66,000 deaths were reported worldwide in the past week as Covid-19 is continuing to spread around the world, the World Health Organization (WHO) announced Wednesday. The number of new infections in seven days surpassed last week's number by 2%, while the mortality rate was roughly flat, the UN agency added. A total of 4,444,632 people were infected with Covid-19 across the world and 66,506 patients died from August 9 to 15.  READ: Bangladesh reports 172 more Covid deaths, 7,248 fresh cases As of August 18, 208,833,116 coronavirus cases had been recorded in nearly 200 countries. Since the start of the pandemic, the Covid-19 death toll has reached 4,386,814. So far, the US, India and Brazil have seen the highest number of confirmed cases and fatalities. In Europe, over 1.1 million Covid-19 cases and more than 10,000 deaths were registered in seven days. In the Americas, more than 1.5 million new Covid cases and over 19,000 deaths were recorded. In Southeast Asia, doctors confirmed over 502,000 Covid-19 cases, while more than 19,000 patients died over the past seven days. Most Covid-19 cases, 883,996, were reported by the US in the past week, according to the WHO. There are many variants of SARS-CoV-2 that can cause Covid. Each variant is the result of a random mutation of the original virus. However, the main variant of concern now in Bangladesh, and indeed worldwide, is the Delta variant.  The variant has undergone some genetic changes that are potentially worrying in terms of transmissibility and vaccine escape. It spreads more quickly than the original virus, increasing the number of hospitalisations or deaths. READ: Global Covid cases top 208 million The Delta variant of Covid-19, detected in October 2020 in India, has now been detected in 148 territories worldwide and 50% more transmissible, the WHO says.