Intensity and frequency of extreme novel epidemics

Abstract

Observational knowledge of the epidemic intensity, defined as the number of deaths divided by global population and epidemic duration, and of the rate of emergence of infectious disease outbreaks is necessary to test theory and models and to inform public health risk assessment by quantifying the probability of extreme pandemics such as COVID-19. Despite its significance, assembling and analyzing a comprehensive global historical record spanning a variety of diseases remains an unexplored task. A global dataset of historical epidemics from 1600 to present is here compiled and examined using novel statistical methods to estimate the yearly probability of occurrence of extreme epidemics. Historical observations covering four orders of magnitude of epidemic intensity follow a common probability distribution with a slowly decaying power-law tail (generalized Pareto distribution, asymptotic exponent = −0.71). The yearly number of epidemics varies ninefold and shows systematic trends. Yearly occurrence probabilities of extreme epidemics, Py, vary widely: Py of an event with the intensity of the “Spanish influenza” (1918 to 1920) varies between 0.27 and 1.9% from 1600 to present, while its mean recurrence time today is 400 y (95% CI: 332 to 489 y). The slow decay of probability with epidemic intensity implies that extreme epidemics are relatively likely, a property previously undetected due to short observational records and stationary analysis methods. Using recent estimates of the rate of increase in disease emergence from zoonotic reservoirs associated with environmental change, we estimate that the yearly probability of occurrence of extreme epidemics can increase up to threefold in the coming decades.

Association between social isolation and reduced mental well-being in Swedish older adults during the first wave of the COVID-19 pandemic: the role of cardiometabolic diseases

“…Our findings highlight the collateral damage of social isolation as a COVID-19 prevention strategy and underscore the need for mental health support for older adults during subsequent waves of the current pandemic. Furthermore, in the unfortunate but highly probable event of a future pandemic on the scale of COVID-19 [ 14 ], the amplified effects of social isolation on people with CMDs should be kept in mind and addressed earlier with focused preventive strategies. Together with reports from other geographical settings, the findings from our study may contribute to an open, cautious, and impartial discussion about what countries have gained and lost as a consequence of the exceptional public health measures (both mandated and voluntary) related to the COVID-19 pandemic.…”

“…Pandemics are predicted to become more intense and more frequent with continued globalization and expansion. To this end, a recent investigation estimated that the probability of a COVID-19-scale pandemic is as high as 2% in any given year [ 14 ]. For the remainder of the current pandemic as well as for inevitable future ones, it is important to assess what is lost and gained by social isolation, particularly for vulnerable populations.…”

Effects of environmental parameters and their interactions on the spreading of SARS-CoV-2 in North Italy under different social restrictions. A new approach based on multivariate analysis

“…Despite the scheme cannot be considered exhaustive lacking other considerations (for instance about mobility and sociality), it emphasizes direct and cooperative effects that emerge from our study as significant in conditioning the pandemic evolution. Besides the comparison of different territories (which inevitably bring their own social and environmental features), also the day-by-day variations of atmospheric parameters inside a defined area can lead to reliable models of pandemic diffusion, and this is especially important under the threat of increasing intensity and frequency of extreme novel epidemics ( Marani et al, 2021 ).…”

Four Global Catastrophic Risks – A Personal View

“…The annual risk of a pandemic similar in scale to that of 1918 is often considered to be in the range 0.5-1.0%, an average recurrence interval of once in 100-200 years (Burns et al, 2008;Fan et al, 2018). However, Marani et al (2021), identify 217 epidemics with known occurrence, duration and number of deaths between 1600 and 1945 and use a generalised Pareto distribution to show that that the mean recurrence time of a pandemic with the same intensity as the 1918 pandemic is about 400 years. They also show a pandemic similar in intensity to COVID-19 (with a death toll of 2.5 million at the time of writing), has a probability of occurring in one's lifetime of about 38% -a probability that may double in coming decades (Marani et al, 2021).…”