Fig. 3.

Near-future model 2 projections and various possible paths to COVID-19 endemicity in BC. A. Projected daily cases for different levels of reopening (shown by changing R), assuming reopening occurs in ending of March 2022. B. Projected daily cases for different lengths of duration of immunity (0.5–1.5 years), at $R_{\mathrm{NPI}}=5$. C. Comparing antigenic drift and shift. Gradual decrease in vaccine efficacy (“drift”) over a 1 year period versus a sudden decrease (“shift”) by 50% over a few days, at $R_{\mathrm{NPI}}=7$. Model output, corrected for testing constraints (black line), is matched to reported cases (grey dots) in BC from December 2021 to March 2022. Orange line indicates reportable cases without further testing constraint. Dotted vertical line indicates further reopening. Where not varied, importation rate $f$ is fixed at 2 cases per 100k per day, and duration of immunity $D$ at 1 year, additional protection for newly-recovered $r_p$ at 90%, and immune-escape capacity $e$ at 75%. Table 1 contains other parameter values and their sources.