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Table 2 Diagnosed case thresholds and intervention trigger timings

From: Simulation suggests that rapid activation of social distancing can arrest epidemic development due to a novel strain of influenza

Threshold Cases R0
   1.5 2.0 2.5 3.5
   Delay until threshold reached (days)
0.05% 15 9 7 6 5
0.1% 30 13 9 8 6
0.5% 150 24 16 13 10
1.0% 300 30 19 15 11
2.0% 600 37 23 18 13
4.0% 1200 46 27 21 15
8.0% 2400 58 32 24 17
  1. This table shows a range of case count trigger thresholds and the consequent delay in intervention corresponding to each threshold. The boldface delays are those for which the final illness attack rate is < 10%, if all four intervention measures are activated at that time and continued indefinitely.
  2. For a case to count towards the intervention threshold it is assumed that the following sequence of events occurs:
  3. a) The individual becomes infected.
  4. b) The individual experiences symptomatic infection.
  5. c) They present to a health care professional in a monitoring scheme.
  6. d) The infection is correctly diagnosed as pandemic influenza.
  7. e) The case is reported to the monitoring scheme.
  8. We assume a 50% ascertainment efficiency, which is the conditional probability that e) occurs, given that both a) and b) have occurred. We assume that there are no false-positive reports of pandemic influenza.