In a recent study posted to the medRxiv* preprint server, researchers estimated monkeypox (MPX) virus (MPXV) transmission and simulated vaccination scenarios using models developed for coronavirus disease 2019 (COVID-19) estimations.

About the study

In the present study, researchers estimated the global MPXV spread by the end of 2022 using the SEIQRDP (modified SEIR) estimation model.

The SEIQRDP model categorizes the total population under seven different categories, which were as follows: susceptible individuals (S), probably MPXV-infected individuals (E, MPX cases during latency), MPXV-infected individuals (I, non-quarantined MPX cases), quarantined individuals (Q, quarantined MPX cases), recovered individuals (R), deceased individuals (D) and non-susceptible individuals (who abide by protective health measures).

The total number of individuals (N) could be obtained by the summation of all seven categories at any particular time. The model coefficients represented the protection rate (α), infection rate (β), the inverse value of the mean latent period (γ), the rates at which MPXV-infected individuals entered quarantines (δ), the time-associated rates of recovery (λ), and the time-associated rates of mortality (κ). Compared to the previously developed SEIR model, the modified model had the P and Q additions.

The team obtained MPX data from https://www.monkeypox.global.health/ website, which contains data from>100 nations with reported MPXV cases. MPX epidemic development was estimated by the model based on the most recent and real-time MPX epidemic information using the refined LS (least squares) analytical technique for inverting the most recent model coefficients.

Results and discussion

The SEIQRDP model estimated that MPXV would transmit to nearly all nations globally by December 2022 due to a globalized transportation system, and the total MPX case count would attain a value of 100,000. South America, Europe, and North America would face significantly greater MPX severity than other global nations.

The five most affected nations would be the US (United States), Germany, Brazil, Britain, and France, with cases exceeding beyond 28,000, 4,000, 20,000, 4,000, and 4,500, respectively. The cumulative estimations for MPX by December 2022 showed a heterogeneous spatial distribution similar to that observed for the COVID-19 epidemic.

The geographical differences in MPX case counts could be due to different lifestyle habits, cultural practices, population count, and measures for infection control among different nations. Vaccinations on a mass scale would confer immune protection against MPXV, such that if 20% and 30% of the individuals receive vaccinations against MPX by December 2022, MPX case counts would reduce by 21% and by 35%, respectively.

During the COVID-19 pandemic, individuals gained experience combating viral infections and took necessary precautions and protective health measures during the ongoing MPXV outbreak. Additionally, smallpox vaccinations have proven effective against MPX and have been administered globally. 

The increase in global preparedness and smallpox vaccinations helped to curtail MPXB spread, leading to declining trends for the 2022 MPXV outbreak. However, the current outbreak may be an initial wave of MPX infections, MPXV may mutate and give rise to variants, or MPX case counts may increase due to climatic changes. Therefore, individuals must remain cautious against MPXV.

Conclusions

Overall, the study findings showed the estimated global spread of MPX by December 2022. The predictions could yield valuable information on the space and time scale of MPXV transmission and a scientific basis to guide decision- and policy-making by governmental authorities worldwide.

The SEIQRDP model could make general estimations; however, in the real world, individuals would take protection measures based on the COVID-19 pandemic experience. Therefore, the actual probability of MPX may be lower than that estimated. Further, the true count of MPX cases is nearly impossible to determine.

Understanding the MPX-causing virus is incomplete, and further investigations on the mechanisms of MPXV transmission and evolutionary mutational characteristics are required. Continued MPXV surveillance efforts are essential to track viral spillover risks and improve global preparedness against MPXV.

*Important notice

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

Written by

Pooja Toshniwal Paharia

Dr. based clinical-radiological diagnosis and management of oral lesions and conditions and associated maxillofacial disorders.