WDHB chief executive Russell Simpson said limiting the number of visitors may be difficult but the measure had been put in place to keep the whole community safe.
One person per patient is still welcome to stay overnight.
"Someone will be on the door at the main entrance to Whanganui Hospital to explain to visitors about the process and talk through why access is limited and what they can do. All other doors to the main hospital, including the larger cafeteria near Lambie House will remain closed to the public," Simpson said.
What you need to know
"We encourage people in our region with whānau and friends in hospital to text and message their loved ones to keep in touch during this uncertain time."
There were no known cases of Covid-19 in the Whanganui region at the time of publication.
People who have been overseas in the last 14 days or in contact with someone who has been overseas in the last 14 days, or are unwell, must not visit patients at the hospital at any time.
