Ministers announced this week that those who have tested positive can end their quarantine after just five days instead of ten — but only after TWO negative lateral flow tests (LFT).
Mrs Wightman said: "It is absolutely crucial that people isolating with Covid-19 wait until they have received those two negative rapid lateral flow tests on two consecutive days to ensure the chance of still being infectious is reduced before returning to work or education.
“Those who leave self-isolation on or after day six are also strongly advised to wear face coverings and limit close contact with other people in crowded or poorly ventilated spaces, work from home if they can do and minimise contact with anyone who is at higher risk of severe illness if infected with Covid.”
The number of new positive tests confirmed on the government's coronavirus dashboard across Northamptonshire this week dropped by around 20 percent to just over 10,000 in the seven days to Thursday (January 13).
The reduction in weekly new cases is the first in the county since late October.
But Mrs Wightman, the county's director of Public Health, warned people still need to be cautious with NHS England reporting another rise in Covid patients in hospitals in Northampton and Kettering.
She added: "It is important people continue to test regularly and lateral flow tests are available to all, despite challenges in distribution over the festive period.
"These can be ordered online and delivered to your home or collected at local pharmacies across the county.
“Secondly, it's important to remember that if residents test positive with an LFT should make sure they register the result on the government website.
"This is vital in tracking the spread of the virus and in getting the right support to those in need."
Latest figures showed 161 patients being treated for Covid in the county's two main hospitals by Tuesday (January 11), up from 150 just five days earlier, while 26 coronavirus patients have sadly died at the two hospitals since January 1.