Analyzing Vaccine Trials in Epidemics with Mild and Asymptomatic Infection.

Analyzing Vaccine Trials in Epidemics with Mild and Asymptomatic Infection. Am J Epidemiol. 2018 Oct 17;: Authors: Kahn R, Hitchings M, Wang R, Bellan S, Lipsitch M Abstract Vaccine efficacy against susceptibility to infection (VES), regardless of symptoms, is an important endpoint of vaccine trials for pathogens with a high proportion of asymptomatic infection, as such infections may contribute to onward transmission and long-term sequelae such as Congenital Zika Syndrome. However, estimating VES is resource-intensive. We aim to identify approaches to accurately estimate VES when limited information is available and resources are constrained. We model an individually randomized vaccine trial by generating a network of individuals and simulating an epidemic. The disease natural history follows a Susceptible, Exposed, Infectious/Symptomatic or Infectious/Asymptomatic, Recovered model. We then use seven approaches to estimate VES, and we also estimate vaccine efficacy against progression to symptoms (VEP). A corrected relative risk and an interval censored Cox model accurately estimate VES and only require serologic testing of participants once, while a Cox model using only symptomatic infections returns biased estimates. Only acquiring serological endpoints in a 10% sample and imputing the remaining infection statuses yields unbiased VES estimates across values of R0 and accurate estimates of VEP for higher R0 values. Identifying reso...
Source: Am J Epidemiol - Category: Epidemiology Authors: Tags: Am J Epidemiol Source Type: research