Viral genetics and transmission dynamics in the second wave of mpox outbreak in Portugal and forecasting public health scenarios

Emerg Microbes Infect. 2024 Dec;13(1):2412635. doi: 10.1080/22221751.2024.2412635. Epub 2024 Oct 11.

Abstract

In 2023, a second wave of the global mpox epidemic, which is mainly affecting men who have sex with men (MSM), was observed in some countries. Herein, we benefited from a large viral sequence sampling (76/121; 63%) and vast epidemiological data to characterise the re-emergence and circulation of the Monkeypox virus (MPXV) in Portugal during 2023. We also modelled transmission and forecasted public health scenarios through a compartmental susceptible-exposed-infectious-recovered (SEIR) model. Our results suggest that the 2023 mpox wave in Portugal resulted from limited introduction(s) of MPXV belonging to C.1.1 sublineage, hypothetically from Asia, followed by sustained viral transmission and potential exportation to other countries. We estimated that the contribution of the MSM high sexual activity group to mpox transmission was 120 (95% CrI: 30-3553) times higher than that of the low sexual activity group. However, among the high sexual activity group, vaccinated individuals likely contributed approximately eight times less [0.123 (95% CrI: 0.068-0.208)] than the unvaccinated ones. Vaccination was also linked to potential reduced disease severity, with a Mpox Severity Score of 6.0 in the vaccinated group compared to 7.0 in unvaccinated individuals. Scenario analysis indicated that transmission is highly sensitive to sexual behaviour, projecting that a slight increase in the MSM sub-population with high sexual activity can trigger new mpox waves. This study strongly supports that continued vaccination, targeted awareness among risk groups and routine genomic epidemiology is needed to anticipate and respond to novel MPXV threats (e.g. global dissemination of clade I viruses).

Keywords: MSM; Monkeypox virus; high sexual activity; second wave; vaccination.

MeSH terms

  • Adolescent
  • Adult
  • Disease Outbreaks*
  • Female
  • Forecasting
  • Homosexuality, Male / statistics & numerical data
  • Humans
  • Male
  • Middle Aged
  • Monkeypox virus* / genetics
  • Mpox, Monkeypox* / epidemiology
  • Mpox, Monkeypox* / transmission
  • Mpox, Monkeypox* / virology
  • Phylogeny
  • Portugal / epidemiology
  • Public Health*
  • Young Adult

Grants and funding

This study was co-funded through the DURABLE “Research Network against Epidemics” project. The European Commission Union has co-funded the DURABLE project under the EU4Health Programme (EU4H), Project no. 101102733. However, views and opinions expressed are those of the authors only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency. Neither the European Union nor the granting authority can be held responsible. The study was also co-funded by the project GENEO “Sustainable use and integration of enhanced infrastructure into routine genome-based surveillance and outbreak investigation activities in Portugal” (https://www.insa.min-saude.pt/category/projectos/geneo/) on behalf of EU4H programme (Project N° 101113460). Constantino Caetano acknowledges the “Fundação para a Ciência e Tecnologia (FCT)” within the PhD grants “DOCTORATES 4 COVID”, grant number 2020.10172.BD.