After the COVID-19 pandemic that has taken a toll on the whole world on multiple aspects, a new infectious disease is lurking just around the corner.  As reported by WHO, 92 confirmed cases of monkeypox has been reported in various non-endemic regions between 13^th to 21^st May, 2022. Although monkeypox is endemic in certain African countries, but it’s for the first time it has been reported in multiple non-endemic countries with the highest number of confirmed cases in United Kingdom, Portugal and Spain. The major concern is whether monkeypox is as contagious as COVID-19? Does it have the potential to turn into a pandemic? Well, it all depends on the Reproduction Number or “R number” of the infectious agent and some researchers have calculated the same for monkeypox which we’ll get in to.

What is Monkeypox?

Monkeypox is a viral zoonosis infection (which means it is transmitted from animals to human) caused by monkeypox virus. This virus is a member of the orthopoxvirus genus in the Poxviridae family. The host of monkeypox virus includes rope squirrels, tree squirrels, Gambian pouched rats, dormice, non-human primates and other species. However, the exact reservoir of the virus is yet to be identified. Also how the virus circulation is maintained in nature needs further studies as well.

Often the virus from the above mentioned animals can be transmitted to humans by coming in close contact through blood, bodily fluids, or cutaneous or mucosal lesions of infected animals. The signs and symptoms are similar to smallpox (now eradicated), but is usually less severe. Since 1970, multiple cases of monkeypox have been reported in different regions of Africa. It is for the first time it has been reported in other countries outside the African continent. Previously studied data showed that monkeypox has a fatality rate of 3%, however among the cases recently detected in different parts of the world, not a single death has been reported as of writing this article.

What is R Number for Monkeypox?

The R Number (Reproduction Number), denoted by the letter “R”, is often used to quantify whether an emerging disease have the ability to invade a population. R is defined as the expected number of secondary infection per primary infection. In other words, R number denotes how many individuals can be infected by one infected individual? When the value of R is above 1, epidemic potential is there.

R number takes in consideration the whole population in question, whereas R₀ considers only the susceptible population. As it has been found that smallpox vaccine offers certain amount of cross-immunity against monkeypox infection, so it is the R₀ value that will determine the the epidemic potential of the infection. If R₀ is above 1, the disease have epidemic potential.

Using the mathematical formula for R₀, researcher Rebecca Grant et al has found the value of R₀ to be 2.13 for monkeypox. As it is more than 1, thus it has the potential for turning into an epidemic. But there’s a catch! The data analysed by the researchers pertained to the population of Democratic Republic of Congo of the 1980s.

Is Monkeypox as contagious as COVID-19?

Like COVID-19; in monkeypox too human-to-human transmission can occur. It can result from close contact with respiratory secretions, skin lesions of an infected person or recently contaminated objects. Infected pregnant mother can transmit the virus to the developing fetus through the placenta. As it is clear that close physical contact is a risk factor for transmission of the virus, but whether it spreads through sexual act is not known yet.

Monkeypox is contagious, but whether it is as contagious as COVID-19, it will depend on the R₀ value. The R₀ of COVID-19 has been estimated to be between 1.5 to 6.68, with the mean value being 3.28 which is more than 1. If we are to accept the study done by Rebecca Grant et al, with the R₀ of monkeypox being 2.13, then an endemic or even a pandemic is possible. However, as the data from which the reproduction number for monkeypox was calculated is limited to a restricted population, it is thus quite early so say if monkeypox is as contagious as COVID-19 or will result in similar case loads like that of COVID-19. However, as we know that the disease is contagious, it is better to exercise the lessons of social distancing we learnt from COVID-19 now, before it is too late.