Only essential visitors and no children visitors are now allowed by the Canterbury District Health Board at all its hospital sites following an RSV outbreak.
This follows many health boards in the North Island making the same call in recent weeks.
There has been a sharp increase in the number of RSV hospital presentations since the travel bubble was opened to Australia in April.
The board said it had made the visiting changes due to the ongoing high levels of respiratory illness in the community.
"This is to reduce the risk of illness spreading to and among our most vulnerable patients, particularly those in maternity, NICU and other child services, and ICU," it said.