Eradicating infectious disease using weakly transmissible vaccines

Abstract

Viral vaccines have had remarkable positive impacts on human health as well as the health of domestic animal populations. Despite impressive vaccine successes, however, many infectious diseases cannot yet be efficiently controlled or eradicated through vaccination, often because it is impossible to vaccinate a sufficient proportion of the population. Recent advances in molecular biology suggest that the centuries-old method of individual-based vaccine delivery may be on the cusp of a major revolution. Specifically, genetic engineering brings to life the possibility of a live, transmissible vaccine. Unfortunately, releasing a highly transmissible vaccine poses substantial evolutionary risks, including reversion to high virulence as has been documented for the oral polio vaccine. An alternative, and far safer approach, is to rely on genetically engineered and weakly transmissible vaccines that have reduced scope for evolutionary reversion. Here, we use mathematical models to evaluate the potential efficacy of such weakly transmissible vaccines. Our results demonstrate that vaccines with even a modest ability to transmit can significantly lower the incidence of infectious disease and facilitate eradication efforts. Consequently, weakly transmissible vaccines could provide an important tool for controlling infectious disease in wild and domestic animal populations and for reducing the risks of emerging infectious disease in humans.

Bayesian estimation of Lassa virus epidemiological parameters: implications for spillover prevention using wildlife vaccination

“…A transmissible vaccine targeting Lassa virus could potentially overcome the significant hurdles confronting traditional vaccination in this system. For instance, using formula derived in (Nuismer et al 2016) along with the estimates for the time-averaged value of R 0 in the Guinean populations we have derived here, shows that even a weakly transmissible vaccine with an R 0 = 1.0 could reduce the number of baits that must be distributed by 56% in Bantou and 68% in Tanganya. A more strongly transmissible vaccine with an R 0 in excess of 1.78 could allow Lassa virus to be autonomously eliminated from these populations.…”

“…In some cases where culling has been employed and studied, however, it has been shown to have potentially counter-intuitive impacts, potentially increasing the prevalence of the target pathogen (Streicker et al 2012; Amman et al 2014). A second alternative to conventional vaccination relies on the use of transmissible vaccines capable of transmitting infectiously within the target population (Murphy et al 2016; Nuismer et al 2016; Bull et al 2018). Transmissible vaccines have been show to substantially improve the likelihood of eliminating infectious disease in theoretical studies, but have been explored empirically in only a small number of cases (Bárcena et al 2000; Angulo and Barcena 2007; Murphy et al 2016; Bull et al 2018).…”

Emerging viruses and current strategies for vaccine intervention

“…Engineering such wild‐life reservoir vaccines to be weakly transmitting, such that their reproduction number is below 1 ( R 0 < 1), making their transmission chains short so that they cannot be maintained, might be a way to address the justifiable safety risks. Indeed, a mathematical model has recently demonstrated the value of such an approach .…”

Transmissible Viral Vaccines

“…This conclusion is misleading for two reasons. First, the transmission from weakly transmissible vaccines (those with R 0 < 1) reduces the direct vaccination effort required to eradicate a disease [40] , so even weak transmission has a measurable benefit. Second, R 0 > 1 is not an assurance of utility: the vaccine may still die out without supplementation.…”