Symptoms of the Delta virus strain

As COVID-19 mutates into new strains, the symptoms are also changing with some signs now more prevalent than others.

Observations of patients with the Delta virus strain in the UK have indicated a cough may no longer be among the telltale signs of COVID-19.

People with Delta strain are reportedly more likely to experience a headache, runny nose and sore throat.

READ MORE: The highly contagious Delta strain explained

Among non-immunised patients, a fever is also a reoccurring symptom of the Delta strain.

Flu-like symptoms of any kind remain common among those with the virus and health authorities are urging people to get tested regardless of the severity of their symptoms.

"I would ask the community not to delay getting a test," NSW Chief Health Officer Dr Kerry Chant said.

"Don't wait to see if you have got a severe illness ... As soon as you get symptoms, go out and get a test."

Delta is rapidly becoming the most dominant strain in Australia, with health authorities scrambling to contain fast-growing outbreaks in multiple states and territories.

READ MORE: Woman with 'health issues' dies after COVID-19 jab

It is widely accepted Delta is more transmissible than the Alpha variant, which is also known as the UK variant.

NSW Premier Gladys Berejiklian said Delta was showing twice the transmission rate of other variants with people contracting the virus through fleeting interactions.

Data from countries to have fought a Delta outbreak suggest the strain moves more easily among children than other strains of the coronavirus.