There were three confirmed cases and 15 suspected cases of the 'Omicron' COVID-19 variant in Welwyn Hatfield as of December 6.
In neighbouring Hertsmere, there were also three confirmed cases of Omicron but only five suspected cases. The unconfirmed cases will be submitted for further testing.
The UK Health Security Agency published localised data for the Omicron variant for the first time last week.
What is Omicron?
There are 50 mutations of COVID-19. Omicron is the most heavily mutated version of coronavirus found so far. It is thought to be more transmissible than other variants and has led the prime minister to ramp up the UK's booster vaccination rollout.
Last night, Boris Johnson announced that now those aged 18 and older will be eligible to get their booster.
Symptoms of the Omicron variant include a runny nose, headache, sore throat, sneezing, loss of smell and a persistent cough.
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