An area in Southend has gone from being virtually Covid free to recording the highest number of cases in south Essex in less than a week.
A total of 16 coronavirus cases were recorded in Leigh in the seven days up to March 30.
That was an increase of 14 from the week before and is by far the highest number of cases anywhere in the region.
It means the infection rate in Leigh is now 152.9 infections per 100,000 people.
By contrast, the average rate of infection in the UK is currently 47.6.
Both Rochford Outer and Hawkwell East, and Rochford Town and Canewdon are the only other areas in south Essex recording infection rates above 100.
Elsewhere, there are more than 20 areas in south Essex which are not highlighted on the Covid hotspots map because they saw fewer than three cases recorded in the lates figures.
It comes as the Government has announced everyone in England will be given access to a free and rapid coronavirus test twice a week from Friday.
The lateral flow tests – which can provide results in around 30 minutes – will be available to anyone, regardless of whether they are showing Covid-19 symptoms.
Rapid testing has so far been available to those most at risk and people who need to leave home for work, including frontline NHS workers.
The wider rollout aims to help the Government identify and control new coronavirus variants, and comes as lockdown restrictions are gradually eased across the UK.
People will be able to obtain a test through a home ordering service, workplace or school testing programme, or by collecting one at a local test site.
A new “pharmacy collect” service is also being launched, which will provide an additional route to regular testing.
Those aged over 18 without symptoms will be able to visit a participating local pharmacy and collect a box of seven rapid tests to use twice a week at home.
Prime Minister Boris Johnson said the rollout will help stop Covid-19 outbreaks “in their tracks”.
He said: “As we continue to make good progress on our vaccine programme and with our road map to cautiously easing restrictions under way, regular rapid testing is even more important to make sure those efforts are not wasted.”
The NHS Covid-19 app is also due to be updated from April 8, with everyone in a group now required to check-in when entering a hospitality venue, rather than just one person.
The app will also require users who test positive to share their venue history in a “privacy-protecting way” via the program, the Government said.
Those who have been at a venue on the same day as several others who have since tested positive for Covid-19 will receive an alert advising them to book a test immediately, regardless of whether they are showing symptoms.