Data-driven estimation of the instantaneous reproduction number and growth rates for the 2022 monkeypox outbreak in Europe

Abstract

Objective To estimate the instantaneous reproduction number Rt and the epidemic growth rates for the 2022 monkeypox outbreaks in the European region. Methods We gathered daily laboratory-confirmed monkeypox cases in the most affected European countries from the beginning of the outbreak to September 23, 2022. A data-driven estimation of the instantaneous reproduction number is obtained using a novel filtering type Bayesian inference. A phenomenological growth model coupled with a Bayesian sequential approach to update forecasts over time is used to obtain time-dependent growth rates in several countries. Results The instantaneous reproduction number Rt for the laboratory-confirmed monkeypox cases in Spain, France, Germany, the UK, the Netherlands, Portugal, and Italy. At the early phase of the outbreak, our estimation for Rt, which can be used as a proxy for the basic reproduction number R0, was 2.06 (95% CI 1.63 − 2.54) for Spain, 2.62 (95% CI 2.23 − 3.17) for France, 2.81 (95% CI 2.51 − 3.09) for Germany, 1.82 (95% CI 1.52 − 2.18) for the UK, 2.84 (95% CI 2.07 − 3.91) for the Netherlands, 1.13 (95% CI 0.99 − 1.32) for Portugal, 3.06 (95% CI 2.48 − 3.62) for Italy. Cumulative cases for these countries present subexponential rather than exponential growth dynamics. Conclusions Our findings suggest that the current monkeypox outbreaks present limited transmission chains of human-to-human secondary infection so the possibility of a huge pandemic is very low. Confirmed monkeypox cases are decreasing significantly in the European region, the decline might be attributed to public health interventions and behavioral changes in the population due to increased risk perception. Nevertheless, further strategies toward elimination are essential to avoid the subsequent evolution of the monkeypox virus that can result in new outbreaks.

Modeling spillover dynamics: understanding emerging pathogens of public health concern

“…During this exponential growth phase of the outbreaks, the instantaneous reproduction number was above one for each of these countries. As shown in a previous study 43 , the basic reproduction number was estimated as 2.06 for Spain, 2.62 for France, 2.81 for Germany, and 1.82 for the UK. However, these reproduction numbers are probably overestimated since some infections may come from spillover events.…”

Modelling COVID-19 mutant dynamics: understanding the interplay between viral evolution and disease transmission dynamics

“…The above reproduction numbers quantify the strain-specific average number of secondary infections that a typical infectious individual generates in a population and are a proxy to approximate variant fitness at the between-host level [12]. All the VOCs that emerged during the COVID-19 pandemic have evolved to maximize their reproduction numbers and hence spread more efficiently than previous variants at the population level [3].…”

“…For SARS-CoV-2 and other viruses with relatively short infectious periods, transmissibility is argued to be the primary driver of evolution, especially in immunologically naive hosts [4]. One of the key quantities used to quantify the transmissibility of a virus is its basic reproduction number R 0 [11,6,12]. A virus can maximize its R 0 by increasing its intrinsic transmissibility, such as enhancing viral shedding, survival outside the host, and the ability to establish infection in new hosts.…”

Mpox outbreak control indicators used in Ontario, Canada: May 21–December 10, 2022

“…These indicators are particularly useful for point source outbreaks (e.g., foodborne illness); however, they may not be applicable to mpox. For example, some studies published during the mpox outbreak used other indicators (e.g., basic reproductive number) to examine the trajectory of cases and rapid growth of the outbreak 6–10 . The objective of this study is to summarize the process used in Ontario to choose key outbreak indicators to monitor mpox control and declare the outbreak over.…”