Speaker
Description
New York City (NYC) experienced North America's largest mpox epidemic in 2022, peaking in July amid vaccine rollout. Sexually transmitted infections tend to spread across scale-free sexual networks, but it is currently unknown whether monkeypox virus (MPXV) transmission lineages recapitulate a similar network pattern. We performed phylogeographic analysis of 765 MPXV genomes from NYC sequenced by the NYC Department of Health and Mental Hygiene and 3288 MPXV genomes sampled globally to examine the number of introductions of MPXV into NYC, the dynamics of their persistence, and whether vaccination contributed to cresting of the epidemic. We inferred over 200 introductions of MPXV into NYC by mid-August 2022, with approximately 74% of importations being international in origin and 81% of exportations from NYC were into the broader United States. Most transmission clusters comprising ≥10 genomes were introduced by July 2022, and the largest transmission lineages were introduced into NYC at the outset of the NYC outbreak near the end of April. These MPXV transmission lineage sizes were best approximated by a Yule-Simon distribution, indicating they are scale-free in nature. This distribution is consistent with the scale-free dynamics that characterize HIV transmission networks, suggesting that MPXV, like HIV, spread across high-risk sexual networks. Lastly, we constructed a general linear model to assess the statistical association between MPXV genomic diversity in NYC, as reflected by inter-coalescent times, and case counts, first vaccination dose, and second vaccination dose. Case counts, but neither vaccination dose, were associated with the inter-coalescent times, suggesting that the start of the vaccination campaign did not have a major role in curbing the mpox epidemic in NYC and, instead, that saturation of the sexual network and potential changes in human behavior resulted in the end of the epidemic. These results indicate that sexually transmitted pathogens can utilize previously unexplored densely connected sexual networks to cause local epidemics.
