WHO: Monkeypox containable, no urgent need for mass vaccinations

Monkeypox is a usually mild viral infection that is endemic in parts of west and central Africa. It spreads chiefly through close contact, and until the recent outbreak has only rarely been seen in other parts of the world. The majority of the recent cases have been reported in Europe.

“We encourage you all to increase the surveillance of monkeypox to see where transmission levels are and understand where it is going,” said Sylvie Briand, WHO director for Global Infectious Hazard Preparedness.

She said it was unclear if the cases were the “tip of the iceberg” or if the peak in transmission has already passed.

Speaking at the World Health Assembly in Geneva, Briand reiterated WHO’s view that it is unlikely that the virus has mutated but said that transmission may be being driven by a change in human behaviour, particularly as people return to socialising as COVID-19 restrictions are lifted worldwide.

Many, but not all, of the cases have been reported in men who have sex with men, and Briand said it was particularly important to try to prevent sexual transmission.

Symptoms include a fever and a distinctive bumpy rash. The West African strain of monkeypox, which is the one identified in the current outbreak, has a mortality rate of around 1%.

While she said the outbreak was “not normal”, she stressed that it was “containable”. There are also vaccines and treatments available for monkeypox, she added, calling for appropriate containment measures, more research, and global collaboration.

“Let’s not make a mountain out of a molehill,” she said

The WHO also does not believe the monkeypox outbreak outside of Africa requires mass vaccinations as measures like good hygiene and safe sexual behaviour will help control its spread, a senior official said on Monday.

Richard Pebody, who leads the high-threat pathogen team at WHO Europe, also told Reuters in an interview that immediate supplies of vaccines and antivirals are relatively limited.

His comments came as the US Centers for Disease Control and Prevention said it was in the process of releasing some Jynneos vaccine doses for use in monkeypox cases.

Germany’s government said on Monday that it was assessing options for vaccinations, while Britain has offered them to some healthcare workers.

Contact tracing and and isolation

Public health authorities in Europe and North America are investigating more than 100 suspected and confirmed cases of the viral infection in the worst outbreak of the virus outside of Africa, where it is endemic.

The primary measures to control the outbreak are contact tracing and and isolation, Pebody said, noting that it is not a virus that spreads very easily, nor has it so far caused serious disease. The vaccines used to combat monkeypox can have some significant side-effects, he added.

It is unclear what is driving the outbreak, with scientists trying to understand the origin of the cases and whether anything about the virus has changed. There is no evidence the virus has mutated, a senior executive at the UN agency said separately on Monday.

Many - but not all - of the people who have been diagnosed in the current monkeypox outbreak have been men who have sex with men. But that may be because this demographic is likely to seek medical advice or access sexual health screening more readily, the WHO said earlier in the day.

Most of the confirmed cases have not been linked to travel to Africa, which suggests there may be large amounts of undetected cases, said Pebody. Some health authorities suspect there is some degree of community spread.

“So we’re only seeing ... the tip of the iceberg,” he said.

Given the pace of the outbreak, and lack of clarity around what is driving it, there has been worry that large events and parties this summer could make things much worse.

“I’m not saying to people don’t have a good time, don’t go to attend these events,” Pebody said.

“It’s rather around what people do at the parties that matters. So it’s about safe sexual behaviour, good hygiene, regular hand washing - all these sorts of things will help to limit the transmission of this virus.”

US preparing to deploy vaccines

The United States, meanwhile, is preparing to give monkeypox vaccines to close contacts of people infected and to deploy treatments, with five cases now either confirmed or probable and the number likely to rise, officials said.

There is one confirmed US infection so far, in Massachusetts, and four other cases of people with orthopoxviruses - the family that monkeypox belongs to, senior officials with the Centers for Disease Control and Prevention said at a press briefing.

All the suspected cases are presumed to be monkeypox, pending confirmation by testing at CDC headquarters, said Jennifer McQuiston, deputy director of the division of high consequence pathogens and pathology.

One orthopoxvirus case is in New York, one in Florida and two in Utah. All those infected so far in the United States have been men.

Genetic sequencing of the Massachusetts case matched that of a patient in Portugal and belonged to the West African strain, the milder of the two monkeypox strains.

“Right now we are hoping to maximize vaccine distribution to those that we know would benefit from it,” said McQuiston.

“Those are people who’ve had contacts with a known monkeypox patient, health care workers, very close personal contacts, and those in particular who might be at high risk for severe disease.”

Greater risk to immunocompromised

In terms of supply, the United States has around one thousand doses of JYNNEOS, a Food and Drug Administration (FDA) approved vaccine for smallpox and monkeypox “and you can expect that level to ramp up very quickly in the coming weeks as the company provides more doses to us,” said McQuiston.

It also has around 100 million doses of an older generation vaccine, ACAM2000.

Both use live viruses but only JYNNEOS is non-replicating, making it the safer option, said McQuiston.

People who are immunocompromised or have particular skin conditions, including eczema, are at greater risk, added John Brooks, a medical epidemiologist.

Transmission of monkeypox occurs through close, sustained skin-to-skin contact with someone who has an active rash, or through respiratory droplets in someone who has lesions in their mouth and is around another person for an extended period of time.

The virus causes a rash, with skin lesions focused on certain areas of the body, or spread more widely. In some cases, during early stages, a rash can start on the genital or perianal areas.

While scientists are concerned that the growing number of cases worldwide may potentially indicate a new type of transmission, so far there is no hard evidence to back that theory, said McQuiston.

Instead, the uptick in cases might be linked to specific spreader events, such as recent raves in Europe that might explain the higher prevalence among gay and bisexual men.

But, warned Brooks, “by no means is the current risk of exposure to monkeypox exclusive to the gay and bisexual community.”

The CDC is also developing treatment guidance to allow the deployment of antivirals tecovirimat and brincidofovir, both of which are licensed for smallpox.