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What are best practices for swabbing monkeypox lesions? Do chickenpox and smallpox vaccines prevent monkeypox? CDC experts answered these and other questions during a call, while also providing a status update on the current outbreak, guidance on treatment options, and advice for pre- and post-exposure prophylaxis.

Monkeypox, a rare zoonotic infection endemic to Western Central Africa, can be life-threatening. The first suspected case in the 2022 outbreak was reported in the U.S. on May 17.

To collect a sample for monkeypox testing, do you need to unroof the lesion?

Bruce Furness, MD, MPH, a medical epidemiologist in the division of STD prevention at the CDC, said he has swabbed more than 10 lesions on different patients, and "not one of them has unroofed."

"These are truly small, rubbery, deep-seated lesions, and unlike HSV [herpes simplex virus] lesions ... you can't really tell whether you've gotten a good specimen or not, based on whether or not there's fluid present, or whether or not there happens to be some bleeding," he noted. "You just have to scrub the swab over the surface of those affiliated rubbery deep-seated lesions as hard and aggressively as the patient can tolerate, because most of these are quite tender."

Capt. Brett Petersen, MD, MPH, the U.S. Public Health Service Deputy Chief, Poxvirus and Rabies Branch, of CDC's National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), said that the lesions "do contain infectious virus"; therefore, it's important to keep the lesions and lesion materials covered to prevent transmission.

Can samples be collected before they become pustular?

Capt. Agam Rao, MD, a medical officer at the U.S. Public Health Service at NCEZID, noted that swabs can be taken during the vesicular phase as well.

In prior outbreaks, some patients had lesions in the mouth before lesions on the skin presented, she explained. "So, you can swab vesicles, pustules, [and] scabs can also be collected and tested," she said, noting that scabs are also a common source of transmission, such as through bedding.

Do prodromal symptoms always precede the appearance of monkeypox lesions?

The "classic presentation" of monkeypox involves prodromal symptoms -- fever, malaise, headache, and swollen lymph nodes -- which precede the emergence of lesions, said Leandro A. Mena, MD, MPH, director of the division of STD prevention at the CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention.

He pointed out that in the current outbreak patients are seeing lesions without any prodromal symptoms, and in some cases symptoms develop after the rash develops.

Does the smallpox vaccine or chickenpox vaccine provide any protection against monkeypox?

Previous smallpox vaccination is expected to provide "some protection" against monkeypox, said Petersen, since the two viruses are related.

In the 2003 monkeypox outbreak, six individuals who had been vaccinated as children acquired monkeypox, but an analysis of cases in that outbreak suggested that "among those who were previously vaccinated, there was a protective effect, even after many decades of receiving the smallpox vaccine," he added.

It isn't yet clear how long after vaccination that protection lasts and CDC researchers are continuing to study this question, he noted.

Chickenpox is a herpes virus in a separate family from monkeypox and smallpox, "so vaccination against chickenpox would not be expected to provide any protection from monkeypox," Petersen explained.

Can a person be infected more than once with monkeypox?

"We have not seen that happen, but that does not mean that it could not happen," said Rao. "Generally, infection with smallpox virus did provide lifelong protection; however, it's not clear if that will apply also to monkeypox virus infections."

The CDC is aware of a single case report of a possible reinfection with monkeypox, but the agency expects that to be a rare scenario, Petersen noted.

"What we don't know is with this new outbreak, and the new epidemiology and route of transmission, whether that may impact some of what was previously seen with monkeypox and other related viruses, like smallpox. So, I think there's still more to learn there," he added.

Could monkeypox be spread easily from person to person, similar to COVID-19?

"Monkeypox is certainly not COVID-19," stressed Rao. Based on prior outbreaks and the current outbreak, monkeypox appears to spread through "direct close contact. So, intimate contact that might happen during sex, but also any other close contact that might occur -- for example, if you live with someone who has monkeypox and you are sleeping on the same bedding and using the same towels."

"It really is not something that you will just pass on to someone walking down the street," she said.

While agency researchers are "keeping an open mind" about the possibility that the virus could be more easily transmitted, "at this time, there's no indication that it would spread the way that COVID spread and spread to as many people, [and] at this time, the risk for the worldwide population ... is low," she added.

In addition to responding to clinicians' questions, Mena presented a case study of one male patient and his evolving symptoms, while Petersen gave an overview of medical countermeasures, including vaccines and biologics that are not commercially available but stockpiled by the U.S. government.

In November 2021, the Advisory Committee on Immunization Practices voted to recommend pre-exposure prophylaxis with , a live non-replicating smallpox and monkeypox vaccine, as an alternative to , a live smallpox vaccine, "for certain persons at risk for exposure to orthopoxviruses." In June, the CDC updated .

Petersen noted that ACAM2000 has risks for serious adverse events, including myopericarditis.

"Myopericarditis has not been reported in association with Jynneos in the limited numbers of individuals that have received the vaccine in clinical trials, and so the risk is believed to be lower than that for ACAM2000," he said.

As of Wednesday afternoon, in the U.S. One case in Florida is listed on the tracker, but included in the case count for the U.K., since the patient was tested there.

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