The "stay at home" instruction for the Bailiwick of Guernsey has been extended until 18 April.
A two-week lockdown, during which islanders could only leave home for three reasons for up to two hours a day, was due to end at midnight.
One change during the extension is that all businesses, rather than just essential ones, can deliver items bought online or by phone.
Non-essential shops will remain closed to the public.
Retailers will have to adhere to social distancing and hygiene guidance, and no more than two employees are allowed on their premises.
It is hoped the move will help islanders' mental wellbeing, support local businesses and help with home working.
Rules for deliveries from 8 April:
- Food and drink deliveries continue. Takeaway outlets must stay closed
- Only essential retail outlets are allowed to open premises to the public
- Goods can only be sold online or over the phone
- Social distancing and hygiene guidelines must be in place
- Businesses may use couriers - who are essential workers - to deliver items or use their own delivery service
- Goods must be packed for delivery by no more than two people, wearing gloves
- The deliveries must take place as part of a planned itinerary, and goods must not be sold by delivery drivers to other parties
- The deliveries must be undertaken by no more than one individual, who must wear gloves
- A 70% alcohol hand gel should be rubbed on the gloves between deliveries
- The goods must be left on the doorstep of premises or in an agreed outside place - there must be no direct customer interaction
Director of Public Health Dr Nicola Brink said while on-island testing was a "huge step, more time was needed to get a real sense of what's happening more widely in the island".
She added: "For now, staying at home is the best way we can stay safe and save lives."
Deputy Gavin St Pier, Chairman of the Civil Contingencies Authority, said: "Our objective has not changed; we must reduce the spread of this infectious disease and make sure our health infrastructure, which includes our frontline nurses, doctors and health and social care workers, are not overwhelmed.
"But we know we need to look after people's physical and mental health and wellbeing.
"That is why we're making some allowance now for a wider range of goods to be delivered to islanders."
He added: "We're also conscious of the economic impact 'lockdown' is having, with some businesses having to furlough or lose staff, or simply close down.
"If allowing deliveries means that happens even a little less, that is to be welcomed."