Table 1. Probability of infection given exposure, the asymptomatic ratio, and the probability of virus detection estimated from outbreak data (n = 434) in 2005–2019, Japan.
| Year | (p) Risk of infection (%) | (s) Risk of asymptomatic infection (%) | (q) Risk of virus-positive outcome (%) |
|---|---|---|---|
| 2005 | 74.3 (67.2–80.7) | 4.4 (1.4–9.9) | 72.5 (64.1–80.0) |
| 2006 | 64.7 (61.8–67.5) | 15.9 (13.2–18.9) | 79.8 (76.6–82.7) |
| 2007 | 59.8 (56.0–63.5) | 25.5 (21.3–30.1) | 87.1 (83.1–90.4) |
| 2008 | 68.9 (64.7–73.1) | 15.7 (11.9–20.1) | 82.4 (77.9–86.4) |
| 2009 | 62.4 (57.3–67.4) | 17.2 (12.5–22.8) | 82.0 (76.3–86.8) |
| 2010 | 65.6 (61.9–69.3) | 18.7 (15.1–22.7) | 88.0 (84.5–91.0) |
| 2011 | 59.1 (55.2–62.9) | 19.1 (15.1–23.5) | 83.6 (79.4–87.4) |
| 2012 | 61.4 (57.2–65.5) | 18.7 (14.5–23.3) | 83.6 (79.0–78.5) |
| 2013 | 65.7 (60.5–70.6) | 18.4 (13.7–23.9) | 94.1 (90.2–96.9) |
| 2014 | 59.0 (53.9–64.0) | 16.6 (11.9–22.1) | 91.1 (87.4–95.3) |
| 2015 | 56.7 (50.8–62.6) | 25.3 (18.8–32.8) | 80.7 (73.5–86.8) |
| 2016 | 71.8 (64.2–78.7) | 24.3 (16.8–33.0) | 92.0 (85.2–96.5) |
| 2017 | 61.8 (53.2–70.1) | 21.3 (13.1–31.5) | 85.5 (76.0–92.5) |
| 2018 | 68.3 (59.8–76.4) | 22.2 (14.1–32.1) | 81.8 (72.2–89.3) |
| 2019 | 59.0 (51.9–65.9) | 15.7 (9.7–23.4) | 95.8 (90.5–98.7) |
Note:
Numbers in parentheses represent 95% confidence intervals. All three parameters were assumed to vary every year.