About 35 per cent of all Americans have been infected with Covid-19 over the past year, according to a new study of the US Centers for Disease Control and Prevention (CDC). CDC estimates that from February 2020 to March 2021, 114.6 million Americans were infected with Covid-19, 97.1 million had symptomatic illnesses and 5.6 million were hospitalised with Covid-19, the Xinhua news agency reported on Saturday.