Data from Canterbury District Health Board shows the booster rate in the region is lagging behind the 100 percent rate for the first dose of the vaccine.
"With Omicron the booster dose makes such a huge difference to the protection from Omicron and it's vital that anyone aged over 18 who had their second dose three or more months ago gets their booster dose as soon as possible.
"With a booster dose on board, most people are 95 percent protected against serious illness or hospitalisation," a spokesperson said.
Meanwhile, changes to the Christchurch Hospital visitor policy took effect this week.
Visitor restrictions include that surgical/medical masks must be worn at all times and that approved visitors or support people should not visit if they're unwell.
People attending the emergency department, people with disabilities and women in labour can have one support person, and parents/caregivers are able to be with their child in hospital.
Other than those exemptions, only approved visitors are permitted on compassionate grounds, a spokesperson said.
"Anyone who is an approved visitor to Christchurch, Christchurch Women's, Burwood and Ashburton hospitals will be issued with a visitor card to present to hospital staff on arrival."
It follows the infiltration of Covid-19 in the community in Canterbury and the wider South Island.
On Tuesday, there were 105 new cases announced in the region. Last week cases were announced at the University of Canterbury and a number of local schools.
