From BBC

Stephen Donnelly, Ireland's Health Minister : The decision to temporarily suspend use of the AstraZeneca Covid-19 vaccine was based on new information from Norway that emerged late last night. This is a precautionary step.

AstraZeneca: The nature of the pandemic has led to increased attention in individual cases and we are going beyond the standard practices for safety monitoring of licensed medicines in reporting vaccine events, to ensure public safety.

(except for where we're not, such as trials on over 65's and long-term side-effects)

Prof Adam Finn, UK's Joint Committee on Vaccination and Immunisation (JCVI): It's highly undesirable to disrupt a complex and urgent programme every time people develop illnesses after receiving vaccine that may be coincidental and not causally related.