The First Minister Mark Drakeford has urged the public to be alert to potential scammers as the Welsh Government's contact tracing system begins.
The system, which has been trialled in half of Wales' health boards over the past two weeks, will mean anyone who tests positive for coronavirus will be contacted by a team of contact tracers and asked for the details of the people they have had close contact with while they have had symptoms.
Contact in this instance means someone you have been within 1m of and had a face-to-face-conversation, had skin-to-skin contact with or have coughed on, or been in other forms of contact with for a minute or longer.
It also includes anyone you have been within 2m of for more than 15 minutes, or someone you have travelled with in a vehicle or sat near on public transport.
All of these contacts will be followed up by the Welsh Government's contact tracing team and asked to self-isolate for 14 days "as a precaution to prevent the virus spreading further."
Mr Drakeford admitted this process was "intensive" but said it was "tried and tested" and has helped to bring other outbreaks of infectious diseases under control.
Asked whether the system could be taken advantage of by scammers pretending to be contact tracers, he urged people to be alert to any calls asking for personal details unrelated to coronavirus - such as bank account information.
"Sadly even in these really difficult times there are people who will try to take advantage of others," he said.
"If you are contacted by anybody who claims to be a contact tracer asking you for information about your bank account or asking you to part with information not to do with coronavirus, that will not be somebody coming from the Welsh Government service", he added.
Mr Drakeford said the contact tracing system would be supported by digital systems from June 8th, allowing people to provide details of any close contacts electronically.
He said Wales also hopes to use the NHS X Covid-19 app, provided it completes its trial phase.
He warned contact tracing will only be successful "if the public support it."
He added: "This is a voluntary process but if we are to control the spread of the virus, we need people’s help and cooperation."
Watch the full coronavirus briefing live below
Mr Drakeford said the new advice is based on "increased knowledge" of how the virus behaves outdoors. He told the briefing: "We know that it survives for minutes on surfaces outdoors compared to hours indoors."
He added that the new relaxed guidelines for shielders is "not an instruction", but an option for those "who are comfortable to take advantage of it."