New Delhi, Nov 26 : UK Health Secretary Sajid Javid sounded an alarm over the new 'worst-ever' super-mutant Covid variant that will make vaccines at least 40 per cent less effective, forcing flights to be banned from South Africa and five other countries, the Daily Mail reported. "Our scientists are deeply concerned about this variant. I'm concerned, of course, that's one of the reasons we have taken this action today," the Health Secretary said. "The early indication we have of this variant is it may be more transmissible than the Delta variant and the vaccines that we currently have may be less effective against it." Experts explained earlier how the B.1.1.529 variant (left) has more than 30 mutations -- the most ever recorded in a variant and twice as many as Delta -- that suggest it could be more jab-resistant and transmissible than any version before it, the Daily Mail reported. The variant, which could be named 'Nu' by the World Health Organization in the coming days, has caused an "exponential" rise in infections in South Africa and has already spread to three countries, including Hong Kong and Botswana, where it is believed to have emerged. No cases have been detected in the UK so far but everyone who has returned from South Africa in the past 10 days will be contacted and asked to take a test. At the moment, around 500 and 700 people are travelling to the UK from South Africa each day, but it is expected this figure could increase as the festive period begins, the Daily Mail report added. /IANS