Investigators model 2 hypothetical cities as interconnected networks with a combined population of 100,000 bisexual, gay, and other men who have sex with men.
A modeling study, which was used to determine optimal allocation of vaccines against the monkeypox virus, demonstrated a road map for public officials to help maximize the impact of a limited supply of vaccines, according to results published in the Canadian Medical Association Journal.1
The findings confirmed that prioritizing vaccines to larger networks with more initial infections as well as a greater risk of the infection spreading is best.1
“Under our modeling assumptions, we found that vaccines could generally avert more infections when prioritized to a larger network, a network with more initial infections and a network with greater epidemic potential,” Jesse Knight, a PhD candidate at the University of Toronto and MAP Centre for Urban Health Solutions of Unity Health Toronto in Canada, said in a statement.1 “Our findings further highlight the importance of global vaccine equity in responding to outbreaks, and also in preventing them in the first place.”1
Investigators modeled 2 hypothetical cities as interconnected networks with a combined population of 100,000 bisexual, gay, and other men who have sex with men. They varied the characteristics of the 2 cities across a range of settings and simulated a rollout of 5000 vaccine doses after the first detected case of monkeypox virus.1
The rollout of vaccine doses was conducted over 30 days that started 45 days after the epidemic seeding, with 10 imported cases, according to investigators.2
Investigators identified the allocation of doses between both cities, which maximized infections averted by day 90 of the simulated model.2
They rooted the simulation in a plausible epidemic situation in Canada and used data from the early monkeypox virus situation in Ontario.1
The findings showed that the strongest factors for optimal vaccine allocation between the cities were the city or network size, the relative reproduction number or the potential for an epidemic in each city, and the share of initial cases.1
If the larger city had a greater potential for an epidemic and most of the initial cases, it was better to allocate the majority of vaccines to that city, according to investigators.1
Investigators varied the reproduction number with 1 parameter, but they also highlighted how many factors could influence local epidemic potential, which included the access to prevention and care, characteristics and density of the sexual network, and the underlying social and structural context of the sexual networks and access.1
“Strategic prioritization of a limited vaccine supply by network-level risk factors can maximize infections averted over short time horizons in the context of an emerging epidemic, such as the current global monkeypox virus outbreak,” investigators said.1
The results emphasized the interconnectedness of regions and population-level perspective is necessary.1
References
1. Monkeypox vaccine modelling study provides road map for vaccination. News release. EurekAlert. November 28, 2022. Accessed November 29, 2022. www.eurekalert.org/news-releases/972151
2. Knight J, Tan DHS, Sharmistha M. Maximizing the impact of limited vaccine supply under different early epidemic conditions: a 2-city modelling analysis of monkeypox virus transmission among men who have sex with men. CMAJ. 2022;194(46)E1560-E1567. doi:10.1503/cmaj.221232
