Monkeypox is almost nothing like COVID-19.
Among the many differences — fortunately, for a world weary of the pandemic — is that monkeypox is far less transmissible.
So although a monkeypox case was identified Wednesday in Massachusetts, along with a handful earlier this month in Europe, infectious-disease experts say it won't mean another global health crisis.
Yet monkeypox is a serious disease, well worth monitoring so it can be contained with the standard tools of public health. Chief among them, in this case, are vaccines (yes, there already is one) and isolating infected people.
Monkeypox is not new. Several thousand cases are reported each year, almost entirely in Africa, though some of the newly reported cases in Europe have no known link to Africa.
Alas, social media already is rife with monkeypox misinformation, perhaps unsurprisingly for a disease with a name that sounds like something out of a bad disaster movie.
To cut through the clutter, we spoke to Brian DeHaven, an associate professor of biology at La Salle University, and Stuart Isaacs, under whom DeHaven did a Ph.D. on pox viruses at the University of Pennsylvania's Perelman School of Medicine.
—What causes monkeypox?
Like COVID, monkeypox is caused by a virus. But the two microbes are not remotely related.
Coronaviruses contain single strands of genetic material called RNA. The monkeypox virus carries its genetic code in DNA, which is double-stranded.
The monkeypox virus is millions of times larger than the one that causes COVID, and it produces proteins that disrupt the defenses in the human immune system.
"They look kind of like bricks," DeHaven said. "They are not subtle."
--How does monkeypox spread?
Monkeypox is so named because it was discovered in colonies of monkeys used for research in 1958.
But it is unlikely that monkeys were the original source, said Isaacs, a virologist and associate professor at Penn. The virus also is carried by rodents.
People can spread it to one another through contact with bodily fluids, lesions on the skin, or mucosal surfaces such as in the mouth or throat, the World Health Organization says. In the United Kingdom, health authorities say cases have predominantly occurred in men who have sex with men.
Sex is not generally considered to be a route of transmission but is theoretically possible, Isaacs said.
The monkeypox virus also can be spread by coughing, but generally through large droplets that fall to the ground within a few feet — not the lighter "aerosol" particles that remain aloft for minutes.
As a result, it spreads much less readily between people than COVID. Each person with COVID tends to pass it on to multiple people, on average (provided they have no immunity), but some people with monkeypox do not pass it on to anyone, DeHaven said.
"You get these flareups," he said, "but then it burns out."
Still, said Isaacs, the disease may now be spreading more easily in Europe, and it is not clear why.
"There seems to be some more human-to-human transmission than we might expect," he said.
—What are the symptoms of monkeypox?
Typically, monkeypox starts with flulike symptoms such as fever, intense headache, and swelling of the lymph nodes.
After one to three days, a rash develops on the face and body, first appearing as flat lesions, progressing to pustules filled with yellowish fluid.
Symptoms can last two to four weeks. Monkeypox can be deadly, but the death rate varies widely from strain to strain, from near zero to as high as 11%, according to WHO.
—Is there a monkeypox vaccine?
Yes. It's the same as the one used to inoculate people against smallpox. It works because the two viruses are so closely related, DeHaven said.
Roughly speaking, the two viruses are about as similar to each other as two strains of the coronavirus that causes COVID.
The smallpox vaccine was routinely administered in the United States until 1972, when that disease was eradicated in this country. As a result, most people under age 50 have no immunity to monkeypox or smallpox.
But unlike with the vaccines for COVID, the smallpox vaccine is effective even after the start of an infection, if given promptly.
Because human-to-human spread is limited, it is unlikely that public health officials would recommend widespread vaccination, Isaacs said. A more likely approach is "ring" vaccination — vaccinating the ring of close contacts around anyone who is infected.
That's why the CDC urges people with possible symptoms to contact their doctor.
"People who may have symptoms of monkeypox, particularly men who report sex with other men, and those who have close contact with them, should be aware of any unusual rashes or lesions and contact their healthcare provider for a risk assessment," the agency says.
Jimmy Whitworth, a professor of international public health at the London School of Hygiene and Tropical Medicine, told Reuters that while the recent outbreaks in Europe are "highly unusual," there is no need for panic.
"This isn't going to cause a nationwide epidemic like COVID did, but it's a serious outbreak of a serious disease — and we should take it seriously," he said.
—How is chickenpox related to monkeypox?
Distantly. Like monkeypox, the virus that causes chickenpox contains double-stranded DNA.
But they're on a different branch of the virus family tree. Despite the name, chickenpox is not a pox virus, but a herpes virus.
In addition to monkeypox, the true pox viruses include smallpox and cowpox.
