Regulation 5 Serious cross-border health threats
For the purposes of these Regulations, “serious cross-border health threat” means a life-threatening or otherwise serious health threat specified in paragraph (2) which—
spreads or entails a significant risk of spreading across the borders of the United Kingdom and at least one member State; or
may necessitate a coordinated response by the UK authorities in order to ensure a high level of human health protection.
The following are specified for the purposes of paragraph (1)—
threats of biological origin consisting of—
communicable diseases;
related special health matters;
biotoxins or other harmful biological agents not related to communicable diseases;
threats of chemical origin;
threats of environmental origin;
threats of unknown origin;
events which may constitute public health emergencies of international concern under the IHR provided that they fall under one of the categories of threats set out in sub-paragraphs (a) to (d).