Scientists have found that coronavirus immunity could only last a few months after a study revealed a decline in protective antibodies. Research by Imperial College London estimated just 4.4% of adults had some form of immunity against Covid-19 in September, when cases began to increase again. This is compared with 6% found to have antibodies between June 20 and July 13, and 4.8% between July 31 and August 31. Experts said the data from the Real-Time Assessment of Community Transmission (React-2) study showed immunity was “waning quite rapidly”, which could lead to an increased risk of reinfection.