Possible global risks of importing monkeypox

In a recent study published in medRxiv* Server, a team of researchers hypothesized different travel restrictions scenarios to estimate the potential global risks of importing monkeypox virus (MPXV).

Study: Impact of airline travel network on global import risk of monkeypox, 2022. Image Credit: Song_about_summer/Shutterstock
Stady: Impact of airline travel network on global import risk of monkeypox, 2022. Image Credit: Song_about_summer / Shutterstock


The World Health Organization (WHO) declared MPXV a global public health emergency on July 23, 2022. Earlier, it was not considered contagious prior to the onset of symptoms; However, several reports have identified an asymptomatic case of MPXV infection raising fears of an outbreak in multiple countries. Even more alarming is that the average incubation time for MPXV is barely 8.5 days and, in some cases, as high as 21 days, but this still makes its accidental import easy.

Furthermore, the global discontinuation of smallpox vaccination in the 1980s, which was considered effective against MPXV and now increases susceptibility to MPXV. All countries are at high risk of importing MPXV because of the global travel network. The outbreak of MPXV 2022 started in the United Kingdom (UK) due to the import of MPXV from Nigeria.

As of September 4, 2022, the United States (US), Brazil, the United Kingdom, Spain and France had the largest total number of MPXV cases. Although it is not a sexually transmitted disease, it has been uniquely spread in these countries by men who have sex with men (MSM). Now that air travel has returned to pre-Coronavirus 2019 (COVID-19) levels, the International Air Transport Association (IATA) expects air passenger volumes to increase by 69% from 2019. It is possible that these travelers will be able to cross borders indefinitely. Accidentally with MPXV infection.

Previously, researchers used mathematical modeling to simulate air transport networks coming from Wuhan, China, where the COVID-19 pandemic began, and to measure the impact of travel restrictions on import risks.

about studying

In this study, the researchers used a mathematical model similar to the one used during the COVID-19 pandemic to estimate the risk of MPXV import. They used public data sources to collect passenger volume data from 1,680 airports in 176 countries that reported confirmed MPXV cases.

The researchers estimated the passenger volume (PV) on an airplane based on the maximum number of seats on that plane. Furthermore, they used the airline network to determine the effective distance, that is, the minimum distance between all possible paths representing the PV weighted path length and the degree of each node corresponding to one airport.

Notably, the effective distance worked assuming that the MPXV started spreading from the UK. However, the team also performed sensitivity analyzes using the convergence centrality index on the airline network to assess the gravity of an airport in the model from the point of view of PV rather than effective distance.

Furthermore, the researchers estimated import risk based on local and global population movement patterns using a survival analysis technique in which the risk function was a function of effective distance. They multiply the PV by 0.93 for the estimate of domestic travel and 0.69 for international travel.

To examine travel restrictions, the researchers selected those scenarios that reduced passenger volumes to/from countries where MPXV cases were detected. Likewise, they focused on those scenarios that increased or decreased global passenger volume relative to the high and low volumes observed in 2019 and 2021, respectively, regardless of MPXV cases.


At similar flight volumes for 2022, the risk of MPXV import was expected to be significant at multiple locations by December 31, 2022. Regardless of distance from London, UK, sites with a large number of PV cells and closely connected flights were more vulnerable. At risk of importing MPXV.

Reducing PV by 50% or 90% to or from countries that already have MPXV import did not change MPXV import risk significantly. The degree of PV had a non-linear effect on reducing the risk of MPXV import because the connection between each airport network also affected the optimum size of downsizing. Reducing PV to reduce the risk of MPXV import may not be an effective strategy for making practical recommendations on travel restrictions.


The study model was not able to effectively capture the complex dynamics of global disease transmission. However, it has shown that airline travel restrictions in most regions may not prevent MPXV import in real-world settings. The results of the study highlight the importance of strengthening surveillance against MPVX in countries with a high risk of importing this virus. In addition, these countries at high risk of importing MPXV should focus contact tracing and insulation techniques.

Moreover, the study findings on travel patterns could inform public health interventions, particularly for understanding the risks of monitoring an emerging disease across borders.

*Important note

medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health-related behavior, or be treated as established information.

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