The Blood Service is encouraging people to donate blood while they are healthy as it aims maintain a continuity of supply as the Covid-19 crisis deepens.

Blood Service spokesperson Asuka Burge said there had been a slight dip in demand for blood products as elective surgeries were postponed, but that only told half the story.

She said donors had to be healthy, so the other half of the equation was the difficulty of having a steady supply.

"Of course donors have to be fit and healthy and well to be able give blood so that probably our primary message for people to check their eligibility," she said.

"Check that they are well, don't have a cold, cough, flu any of that sort of thing and that they book before they come and donate."

Burge said there was no shortage of blood products at present.

"Thankfully we already have a great group of donors who give regularly so coming into this period we had some healthy blood stock levels and now the challenge for us is to maintain those."

It was important to align supply of blood products with demand, Burge said.

"So that is why we are asking people to book in and also that that will be ongoing so even if they can't give this week or next week it might be the week after they are needed."

Burge said the Blood Service was an essential service so people could still travel to donate blood and extra steps were being taken at its clinics to make sure the procedure was safe.

By RNZ