Flu-like symptoms have long been the common key marker in those with Covid-19 but now a new symptom has emerged. 

Children, and some adults, infected with the virus are increasingly presenting with gastro symptoms, including diarrhoea, vomiting and cramps. 

Yesterday, director-general of health Dr Ashley Bloomfield confirmed the symptom, particularly in children. 

Starship emergency department paediatrician Dr Mike Shepherd says the symptoms are typical of a viral illness in children. 

Shepherd said that they are seeing around 30 Covid-positive children in the department each day and that a "reasonable proportion" of them had the gastro symptom. 

He said other symptoms concerned parents should look out for includes fluid uptake levels, lethargy, breathing issues and pain that is not able to be managed with paracetamol or ibuprofen. 

"What we're trying to reassure people is that Covid is a mild illness in most children, so the things to look out for are really the same things we'd suggest you look out for in any illness in children," said Shepherd. 

A Ministry of Health spokesperson said their advice was unchanged and that children should still only get tested if they had flu-like symptoms. 

While gastrointestinal symptoms could occur in children with Omicron, a sore throat and runny nose are the most common symptoms, she said. 

"Therefore, our advice remains the same; keep your child at home if they are sick, get them tested if they have a flu-like illness, and seek medical care if their symptoms worsen." 

In a video, Starship explained the other symptoms children could have include a lack of appetite, fatigue, tummy pain and muscle aches alongside common symptoms of a runny nose, cough, fever and a headache. 

This comes as the child vaccine uptake has stalled – while it started strong, it appears the roll-out began to slow in February. 

Fifty per cent of children between the age of 5 and 11 have received one dose. 

The percentage of tamariki vaccinated around the country is hugely variable – ranging from 62 per cent in Capital and Coast to just 28 per cent in Northland. 

It's nearly been eight weeks since children were able to get their first dose but for most the second round of vaccination has not begun. Some with special immunity issues have been able to receive the second paediatric dose. 

As of yesterday, Ministry of Health data – recorded since August 16, 2021, the start of New Zealand's Delta outbreak – indicates that children aged between 0 and 9 make up for 10 per cent of total cases (113,650). 

Those aged between 10 and 19 made up 23 per cent of the total – this is the second-highest percentage among all age groups.