A top public health boss has warned of a "small" rise in coronavirus cases as lockdown eases but feels Hertfordshire can avoid a “serious” third wave of the virus.

Jim McManus, Hertfordshire’s director of public health, said a “massive” third peak of the virus “is not inevitable” if people continue to follow coronavirus rules.

But he said people should expect an increase in case numbers after every step of the government’s road map out of lockdown, with restrictions gradually easing over the coming weeks.

“It is only sensible to do that as that it was happened last year, so we have tried to plan for that,” Mr McManus said during a press briefing on April 7.

“We don’t know how large it will be, so we have modelled it for every stage.”

Lockdown rules eased further on March 29, with up to six people or two households allowed to meet outside.

And from April 12, people across the country will be allowed to return to shops, gyms and close contact services such as hairdressers and beauty salons.

Bars, pubs and restaurants will also be allowed to serve customers outdoors, but groups will be limited to two households or by the 'rule of six'.

Mr McManus added: “We don’t think it (cases) will be large enough to call it a surge, you might get a spike in younger adults and we are expecting it over the first three or four weeks of step two as people will be socialising more and let their guard down and the key thing is for them not to."

He added: “There will be a small increase in numbers but if we do what we have been doing over the last few months we can keep that increase very small.”

Mr McManus also said Hertfordshire has a new ‘outbreak plan’, which will have an increased focus on contact tracing and self-isolating rules.

He announced the plan as he said the county has the possibility of avoiding a third wave, saying rules around distance, face coverings and ensuring people take correct hygiene measures will help prevent it.

He said: “You have lots of talk about whether there will be a third wave and a massive third peak is not inevitable; it is avoidable if everybody in Hertfordshire does what they have been doing the last few months and then we will avoid a serious third peak.

“We can avoid a massive third peak if we do what we have been doing. One of the things people need to get really clear is the need to keep their distance.

"You do have cases where people are walking into infected aerosol because they are getting too close and I think sometimes people don’t appreciate the distance issue.”

Speaking about how the new ‘outbreak plan’ would work, Mr McManus said: “Every positive case in Hertfordshire immediately comes to us for contact tracing, we don’t give national any time to do it.

"We are ramping up the work on self-isolation and also started to use epidemiological network graphing where you graph the contacts and exposures between people using the data we have so we can investigate clusters.”