Britain's much-maligned multi-billion pound Covid-19 test-and-trace system has improved, but is still missing targets and the results of millions of tests to find asymptomatic cases have not been reported, Parliament's spending watchdog said on Friday.

The programme, which was given a £22 billion (RM127.32 billion) budget, was launched by Prime Minister Boris Johnson in May 2020 to oversee testing of those who thought they had the virus and then to trace the contacts of those who tested positive.