Recent changes in CDC guidelines highlight a lesser-known phenomenon: Monkeypox can also sometimes be transmitted by aerosol, similar to the coronavirus.

According to a post by New York TimeLast week, the CDC updated its guidelines for travelers looking to protect themselves from monkeypox. This is one of his recommendations: “Wear a mask. Wearing a mask can help protect you from many diseases, including monkeypox.”

As of Monday night, the recommendation had been removed.

“The CDC removed the mask recommendation from the travel health guidelines for monkeypox because it caused confusion,” the agency said in a statement.

However, the agency still points out that in countries where this type of smallpox is spreading, “household contacts and health care workers” should consider wearing a mask. The guidelines also apply to “other persons who may have had close contact with someone who has been confirmed to have monkeypox.”

The changes capture a little-discussed aspect of the current outbreak: The virus can be transmitted through the air, at least over short distances. Although experts have assured in various interviews that airborne transmission is only a minor factor in overall spread, there is no firm estimate of how big the contribution will be.

In previous outbreaks, most infections were reported in people who had close contact with infected patients or animals. However, in some cases, airborne transmission is the only explanation for the infection.

Elsewhere on its website, the CDC still urges monkeypox patients to wear surgical masks, “especially those with respiratory symptoms.” Authorities also recommend that people living with those infected “consider wearing a surgical mask” when they come into contact with people infected with this type of smallpox.

Monkeypox is supposed to behave like its viral cousin, smallpox. In a 2012 review of smallpox transmission, University of Maryland virologist Donald Milton described several cases of airborne transmission.

In 2017, scientists studying an outbreak of monkeypox in Nigeria looked at cases of transmission in prisons and recorded infections from two health workers who had no direct contact with patients.

Last week, the World Health Organization held a scientific conference where several researchers discussed the many emerging unknowns about monkeypox, including its main mode of transmission.

“It’s very ambiguous to determine the correct or dominant transmission pathway, and some of these can be addressed in animal models,” Nancy Sullivan, a researcher at the National Institute of Allergy and Infectious Diseases, told the conference. “That may need to be a priority in some laboratory studies.”

But in briefings with the press and the general public, health officials have not explicitly discussed the possibility of airborne transmission or the use of face masks for protective purposes.

And in interviews, they emphasized the role of large respiratory droplets expelled by infected patients and reaching objects or people. Monkeypox infection requires “very close contact,” said Andrea McCollum, a CDC virologist.

“This is not a virus that spreads a few meters,” he said. That’s why we have to be very careful when dealing with this.”

Asked whether health officials should make the possibility of airborne transmission more widely known, McCollum said, “This is a good question, and one that we should consider moving forward.”

For many, the CDC’s quick change of masks for travelers worried about smallpox is reminiscent of many of the early days of the pandemic, when authorities denied that the coronavirus spread through the air. In September 2020, the agency published guidelines on airborne transmission of the virus, then abruptly withdrew it a few days later.

It wasn’t until May 2021 that the agency acknowledged that the coronavirus could “remain in the air for minutes to hours.”

Most of the information about monkeypox is obtained from smallpox studies. Over the past two decades, scientists have studied how smallpox spreads, including its presence in tiny droplets called aerosols, to prepare for its possible use by bioterrorists.

“Most people think that smallpox is usually transmitted through large droplets, but for some reason it can sometimes be transmitted via aerosol of small particles,” said Mark Challberg, a virologist at the National Institute of Allergy and Infectious Diseases.

As the monkeypox outbreak continued, many patients isolated themselves at home because their symptoms were mild. Members of the household may need to consider the possibility of airborne transmission, experts say.

Many questions remain about monkeypox, including why the current outbreak has produced only relatively mild cases. Scientists don’t know whether people can transmit the virus even without symptoms, how long it has been circulating in the community, and whether it can be transmitted through semen or vaginal fluids.

The publication highlights that since May 13, when the first cases of the outbreak were reported, more than 1,000 people in 31 countries have been diagnosed with the virus, and at least 1,000 more cases are being investigated. As of Tuesday, the United States had recorded 31 cases in 12 states and the District of Columbia.

The World Health Organization has reported more than 780 cases of monkeypox outside Africa, in 27 countries where the disease is not stationary.

Among the countries with the most cases detected were the UK (207), Spain (156) and Portugal (138), the UN health agency determined when closing data from May 13 to June 2.

Also includes Belgium, France, Italy, Sweden, Germany, Switzerland, Austria, Norway, Denmark, Netherlands, Slovenia, Czech Republic, Finland, Ireland, Malta, Canada, Australia, United States, Israel, United Arab Emirates, Argentina and Mexico .

Cuba has confirmed that so far no cases of the disease have been reported, but remains vigilant and is working to develop a treatment protocol for it, according to information from the Ministry of Public Health.

(With information from New York Time)