Probability of type-specific oral HPV infection detection depending upon the proportion of the two-week visits that an infection was detected, stratified by six-month categorization as persistent, absent, cleared or newly detected infection.

For each six month interval categorization of oral HPV type-specific infection status (+/+, −/−, +/−, −/+), the probability of observing a positive test result for a fixed proportion of two week interval visits or greater is plotted as a function of the proportion of two-week interval visits (P). The vertical grey line highlights the case in which at least half of the visits are positive, P = 0.5 (see results text).