Giving blood makes a 'big difference to people's lives'
Northern Ireland's Blood Transfusion Service has said donations have fallen by more than a third.
The organisation told BBC News NI that issues caused by the pandemic meant blood stock was "significantly down".
Matt Gillespie, supply chain and testing manager for the service, said at this time of year they would expect to have more than 1,000 units.
"This morning we're sitting at 600 units of blood," he said.
He added that fewer donors were booking appointments.
"Even the donors that have booked, we have experienced a high number of cancellations and people not showing up.
"When we've looked into this, it's because people are either positive [for Covid-19], they've been in contact with people who are positive, or other Covid-related reasons why they're staying away."