As of September 21, the current monkeypox outbreak has infected 62,532 people in 105 countries. However, the World Health Organization (WHO) has not yet classified the current number of cases as a pandemic.
But can this change? Given its prevalence, it can monkey pox become a pandemic?
The answer to this question depends on the definition of “pandemic”. A pandemic is a “worldwide epidemic” in which there are large numbers of cases or outbreaks in many countries, Rachel Roper, a professor of microbiology and immunology at East Carolina University in Greenville, North Carolina, told Live Science in an email.
“I think it’s a matter of opinion how many cases you should have in how many countries,” Roper said. of Centers for Disease Control and Prevention (opens in new tab) (CDC) defines a pandemic as “a disease event in which there are more than expected cases of a disease spread across several countries or continents, usually involving person-to-person transmission, and affecting large numbers of people.”
There is always the possibility that something, such as the genetic code of the virus, will change, but several factors reduce the chances of monkeypox becoming a pandemic. Even if it does, monkeypox won’t come close to the toll of the COVID-19 pandemic, experts told Live Science.
Historically, monkeypox has not been highly contagious and outbreaks have been small
Monkeypox (sometimes abbreviated as MPXV or MPX) “is much less contagious than COVID,” Roper said. Typically the chain of monkeypox transmission was short — a case of MPXV was transmitted to about seven people at most before it died, so outbreaks have been short-lived in the past, Roper said. Monkeypox was first documented to infect humans in 1970, and outbreaks since then, excluding the current pandemic, have been “somewhat small,” she said. In countries where it is endemic, monkeypox is always present in animal hosts and usually spreads between humans only when they catch it from animals and begin to transmit it to other humans.
But an analysis of monkeypox genomes from the current epidemic, published June 24 in the journal Nature Medicine (opens in new tab)suggests that the version of the virus currently circulating has passed from person to person in an uninterrupted chain of transmission since 2017. This indicates that the average chain of transmission is increasing, Roper said.
However, for monkeypox, the reproductive number (R0), or the number of people directly infected by each person with the disease, has historically been less than 1, meaning that any epidemic would eventually burn out even without active control measures. of the disease (On the contrary, according to Conversation (opens in new tab).) But researchers don’t know the R0 for the currently circulating version of monkeypox, according to a June 2022 Gazette (opens in new tab) in the journal The Lancet Infectious Diseases.
It’s hard to say why monkeypox is infecting so many people now, she added. It could be because mutations have made it more transmissible, or it could be because it has entered new populations that altogether have different behaviors or risk factors that increase transmission rates, Roper said.
For example, in African countries where monkeypox is endemic, the virus was not previously known to spread through men who have sex with men, Roper said. According to World Health Organization (opens in new tab) (WHO).
Monkeypox changes very slowly
Monkeypox is a virus created by DNA, unlike that which consists of single-stranded ribonucleic acid (RNA). This matters because DNA replication involves fewer errors than RNA copying, so monkeypox mutates more slowly than counterparts like SARS-CoV-2 or HIV. This gives monkeypox viruses less opportunity to evolve to become more transmissible than RNA viruses, according to American Society for Microbiology (opens in new tab).
However, for a smallpox virus, monkeypox is mutating quickly, according to the Nature Medicine genome analysis in June. Compared to strains circulating in 2018 and 2019, the virus currently circulating has 50 mutations, most likely picked up during circulation in humans, according to the paper. This is six to 12 times the number of mutations expected based on the typical mutation rate for smallpox viruses, the paper’s authors noted.
Not a lung virus
The virus that causes COVID-19 is “predominantly respiratory,” Roper said. Its main target organ is the lungs. SARS-CoV-2 is spread when an infected person sneezes, coughs or even just breathes, Roper said. In contrast, monkeypox is primarily spread by “direct contact with the monkeypox rash, scabs, or body fluids from a person with monkeypox,” according to the Centers for Disease Control and Prevention (CDC). The virus can also be spread when a person touches objects and surfaces that have been used by someone infected with monkeypox.
“Monkeypox is so inefficient in the way it spreads,” Rodney Rohde, professor and chair of clinical laboratory science at Texas State University, told Live Science. “You have to be very close, in skin-to-skin contact, or maybe with clothing like bed linen or clothing. And it actually takes a long time, hours of contact, for that to happen, while [for] an aerosolized virus, it can be instantaneous — someone sneezes or coughs in a room and you inhale it, and maybe 8, 10, 12 people get it.”
We already have vaccines and treatments for monkeypox
Two vaccines, JYNNEOS and ACAM2000, have been approved for use against monkeypox in the US, as Live Science previously reported.
While there are no specific treatments for monkeypox, according to CDC (opens in new tab)antiviral drugs that have been developed to fight smallpoxsuch as tecovirimat (TPOXX), may be recommended for people with weakness immune systems.
Given the existence of vaccines and treatments, combined with other factors, such as the low death rate of the type of monkeypox currently circulating, it should be possible to slow the rate of infection and limit deaths, Rohde said. The fatality rate for the type of monkeypox circulating in the current epidemic has historically been about 1%, according to CDC (opens in new tab). But the current outbreak may be far less deadly; Based on WHO numbers from the end of September, the mortality rate is 0.04%. While these numbers are still a rough estimate, they suggest that the number of monkeypox is likely to be much, much lower than that of COVID-19, even if monkeypox becomes a pandemic. “It could be considered a pandemic at some point because of the number of countries that have cases and the kind of linear increase in cases that we’re seeing,” Rohde said. “But I don’t believe it will be the kind of global mortality crisis we saw with COVID.”
Originally published in Live Science.