Now, it is unarguable that cyber threats arising from malicious codes such as worms possesses the ability to cause losses, damages and disruptions to industries that utilize ICT infrastructure for meaningful daily work. More so for wireless sensor networks (WSN) which thrive on open air communications. As a result epidemic models are used to study propagation patterns of these malicious codes, although they favor horizontal transmissions. Specifically, the literature dealing with the analysis of worms that are both vertically and horizontally (transmitted) is not extensive. Therefore, we propose the Vulnerable–Latent–Breaking Out–Temporarily Immune–Inoculation (VLBTV-I) epidemic model to investigate both horizontal and vertical worm transmission in wireless sensor networks. We derived the solutions of the equilibriums as well as the epidemic threshold for two topological expressions (gleaned from literature). Furthermore, we employed the Runge-Kutta-Fehlberg order 4 and 5 method to solve, simulate and validate our proposed models. Critically, we analyzed the impact of both vertical and horizontal transmissions on the latent and breaking out compartments using several simulations experiments.