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.
For a case to count towards the intervention threshold it is assumed that the following sequence of events occurs:
a) The individual becomes infected.
b) The individual experiences symptomatic infection.
c) They present to a health care professional in a monitoring scheme.
d) The infection is correctly diagnosed as pandemic influenza.
e) The case is reported to the monitoring scheme.
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.