Fig. 3.

In mid-December 2021, the expected number of spillovers to NL community members was the highest it had ever been. High spillover risk in mid-December 2021 was due to the establishment of the Omicron BA.1 variant in Canada and high numbers of imported cases (A), and low vaccine efficacy for NL community members with two doses of vaccine exposed to the Omicron variant (C). (A) Imported cases, $D\left(t\right)$. (B) The stringency of post-arrival travel restrictions, $1-m_j\left(t\right)$. (C) The probability of a symptomatic infection given exposure when considering vaccination of NL community members, $x^C\left(t\right)$. (D) The stringency of NPIs implemented in the NL community, $\omega \left(t\right)$. (E) The expected number spillovers, NL community members infected by travellers and their close contacts, $\overline{\sigma }\left(t\right)$ (black - Eq. (5); with variant-specific numbers shown with colours). The timing of actual community outbreaks with more than 5 cases are shown along the bottom bar. Grey dashed vertical lines show post-arrival travel restrictions due to different Special Measures Orders (see Table 3).