All contacts of a positive case who are fully vaccinated, under 18 years and 6 months, participating in an approved vaccine trial, or unable to have the vaccine for medical reasons are exempt from the requirement to self-isolate. Instead of needing to self-isolate, these contacts are advised to take daily lateral flow device (LFD) tests for seven days to help identify asymptomatic cases quickly to break chains of transmission.
It is only unvaccinated contacts of a positive case that are now legally required to self-isolate if notified by NHS Test and Trace or a local authority contact tracer, unless they are taking part in an approved Workplace Daily Contact Testing (DCT) scheme. If they are not taking part in a Workplace DCT scheme they do not need to take LFD tests. If they choose to take a LFD test and it is negative, they must continue to self-isolate, because they could still become infectious.