Are We Going to Have a Monkeypox Pandemic?
We don’t want to underestimate the disease, but it seems unlikely to become a COVID-like pandemic based on its epidemiological characteristics.
Emerging Cases in Europe and North America
You’ve probably heard about emerging cases of monkeypox in the news. New cases were reported in multiple countries, including Italy, Spain, Portugal, France, the UK, Belgium, Germany, Sweden, Australia, and Canada. According to the World Health Organization (WHO), as of May 21, there were 92 confirmed and 28 suspected cases. Most infected individuals have occurred in "men who have sex with men seeking care in primary care and sexual health clinics."
In the US, the Centers for Disease Control and Prevention (CDC) confirmed a case in the State of Massachusetts last Wednesday. The patient got infected after traveling to Canada. There is also a suspected case in New York.
This sounds very scary! And we are still not out of the woods yet with the COVID pandemic. The question is: Are we going to have a monkeypox pandemic similar to that of COVID?
Below I summarize what the CDC says about this disease and analyze the likelihood of having a COVID-like pandemic based on previous academic journal publications. You can click the embedded links to learn more.
Symptoms, Medications, and Vaccines
Monkeypox is caused by the monkeypox virus, a member of the orthopoxvirus genus that also includes the virus causing smallpox.
It usually takes 7 to 14 days (maybe 5 to 21 days) before symptoms appear. An infected individual has “fever, headache, muscle aches, and exhaustion” initially. One to three days (maybe longer) after a fever starts, the patient develops a rash, “often beginning on the face then spreading to other parts of the body.” The disease is often self-limited and lasts two to four weeks.
No effective and safe treatments have been approved by the Food and Drug Administration (FDA). However, two drugs for smallpox, TPOXX (tecovirimat) and Tembexa (brincidofovir), were approved by the FDA in 2018 and 2021, respectively. TPOXX was approved by the European Medicines Agency to treat monkeypox and cowpox as well.
In addition, a monkeypox vaccine was approved by the FDA in 2019, called “Jynneos.” An individual needs to take the first dose of the vaccine before exposure to the virus and the second after four weeks.
Epidemiological Characteristics
The first monkeypox case was diagnosed in the Democratic Republic of the Congo in 1970. Since then, the disease has spread to other countries in Central and West Africa. A recent outbreak started in Nigeria in 2017, with more than 200 confirmed and 500 suspected cases, according to the WHO. As illustrated in the figure below, during the last five decades, the number of cases has increased exponentially.
The monkeypox virus is transmitted via respiratory droplets, close contact with infected individuals or animals, or handling contaminated materials. This is very different from COVID which can be transmitted via aerosols and thus is an airborne disease.
In epidemiology, the basic reproduction number (R0) is used to measure the transmissibility of an infectious disease in a population without any immunity. An R0 of 2, for example, means that for every primary case, two secondary cases are expected to occur. The effective reproduction number (R) reflects the actual transmissibility after considering the existing immunity of a population.
Based on existing published research, monkeypox has an R0 of 2.1. This is much smaller than that of COVID (the initial strain: 4.1; the delta variant: 5.1; and the omicron variant: 8.2).
Given that the US stopped smallpox vaccination in 1972, we can assume that those aged 50 years or more had the smallpox vaccine, 36% of the current US population. Also, smallpox vaccination has an 85% efficacy against monkeypox. We can derive that monkeypox has an expected R of 1.5 (=2.1 x [1 - 36% x 85%]); an R greater than one indicates that there would be an epidemic in the US if no effective interventions were implemented.
However, the CDC can mobilize resources to control the disease. For example, infected individuals can be quarantined and treated, and healthcare workers and vulnerable populations can be vaccinated; we are in a much better shape than we were in 2020 when COVID started. All these possible measures should give us a reason to be optimistic that monkeypox will be kept under control.
How to Prevent Infection as an Individual
The CDC has several recommendations:
avoid contact with animals that may have the virus as well as any contaminated materials (In the last outbreak in the US, prairie dogs were found to harbor monkeypox virus);
wash hands with soap and water or use alcohol-based hand sanitizer; and
use personal protective equipment if we need to take care of monkeypox patients.
Takeaways
Despite emerging monkeypox cases in many western countries, the disease’s epidemiological characteristics suggest that it is very different from COVID. It has a much lower R0 than that of COVID. Although it has an R that is greater than one, with the existing medications and vaccine, it is very unlikely to become a pandemic like that of COVID.
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The article is provided by Analytica Now, a company specializing in health analytics, economics, and policy. The article represents the author’s views and does not reflect those of Analytica Now.