A new MPOX vaccine using the same technology as Covid vaccines and currently being tested in Britons reduces symptoms and transmission of the deadly virus, research shows.
Created by pharmaceutical giant Moderna, the new vaccine, dubbed mRNA-1769, was tested directly against a deadly strain of mpox in a trial involving macaques, a type of primate.
It was also compared to a vaccine currently used to protect people against the virus that is designed to work against smallpox, which is closely related to mpox.
The mRNA vaccine, they found, reduced the number of mpox lesions, a classic symptom of the disease, in the monkeys by 96 percent and also reduced the number of days of illness by 10.
Swabs used to analyze the macaques’ blood and saliva also indicated lower viral loads among animals that received the mRNA vaccine.
Created by pharmaceutical giant Moderna, the new vaccine, dubbed mRNA-1769, was tested against a deadly strain of mpox directly in a trial using macaques, a type of primate.
This, the authors suggested, could mean it is more effective at reducing the chances of monkeys transmitting mpox to other animals.
The results come a week after experts warned that currently available vaccines may not work against a new strain of mpox that is sweeping through central Africa and has now reached Europe and Asia.
This new strain, called clade 1b, is much more lethal than the clade 2 strain that spread globally in 2022 and primarily affected gay and bisexual men.
While Moderna’s study did not test its vaccine against clade 1b, it did test it against clade 1a, which is a close relative and also more lethal than clade 2.
In the study, whose results are published in the journal CellThe scientists tested three different groups of six macaques.
One group was given the new Moderna vaccine, another the classic MPOX smallpox vaccine, and the last group was left unvaccinated as a control group.
The vaccinated monkeys received their dose four weeks after being exposed to the lethal mpox strain.
The experts then monitored the animals for four weeks and performed regular blood tests to examine their immune response.
At the end of the trial, all 12 vaccinated monkeys survived, while five of the six unvaccinated macaques died.
Although both injections reduced the severity of mpox infection, the scientists found that the mRNA injection appeared to be much more effective.
For example, monkeys not vaccinated with mpox developed a maximum of 1,448 lesions, while those given the standard vaccine developed only 607, a drop of nearly 60 percent.
But animals that received the mRNA vaccine only developed a maximum of 54 lesions, a difference of 96 percent.
Monkeys that received the mRNA vaccine were also sick for less time and the lesions disappeared 10 days faster than those that received the older vaccine.
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This pattern was also replicated in other measures of disease severity: monkeys that received the mRNA vaccine lost less weight during their illness than those that received the traditional vaccine.
The Moderna team also said results from blood and throat swabs showed lower levels of virus in the bodies of monkeys that received the mRNA vaccine.
They suggested this could “be more effective in reducing transmission.”
Alec Freyn, a Moderna virology researcher and co-author of the study, said the experiment was the first to test an mpox vaccine in development against current vaccination options.
“When we tested those vaccines in primates, we saw improved responses from the mRNA vaccine in terms of not only protection against survival, but also fewer lesions, shorter duration of disease, and less viral shedding in the blood and respiratory tract,” he said.
Author Galit Alter, a virologist and immunologist at Moderna, said the mRNA technology behind the vaccine — the same one used to make the company’s Covid vaccines — was responsible for the increased protection.
“With the mRNA vaccine, we can select parts of the virus that can generate the most potent and effective immune response,” he said.
“By doing that, instead of being distracted by an entire virus, you can focus on the parts of the virus that give you protection.”
In the case of mRNA-1769, the vaccine targets four parts of the virus that are essential for it to attach to and enter human cells.
An additional part of the study was testing antibodies generated by the monkeys’ immune systems that are designed to fight pathogens like mpox and other viruses.
Mr Freyn said these results were positive.
“It not only neutralized monkeypox, but also vaccinia, cowpox, rabbitpox, camelpox and ectromelia. We believe this vaccine can protect against other threats that may arise in the future.”
mRNA-1769 is currently being tested in 350 Britons in England aged 18 to 49.
This trial is designed to measure the safety of various doses of the vaccine and the immune response in humans.
Unlike the newly published research, it does not involve human exposure to potentially lethal MPOX. It is scheduled to be completed in June next year.
While Moderna’s authors did refer to the current outbreak in their study, they did not speculate on the potential efficacy of their new vaccine in this context.
The new strain of mpox, formerly known as monkeypox, is much more lethal than the mild strain that spread to more than a dozen countries, including the United Kingdom, in 2022.
It kills about one in 20 adults it infects, but the mortality rate rises to one in 10 in children.
By comparison, clade 2 only killed about one in every 500 people who contracted it.
The virus is spread mainly through skin-to-skin contact, which may include sexual intercourse, or through direct care, for example from mother to child.
Clade 1b has swept through Central Africa, killing hundreds of people since the outbreak began.
A woman cares for her baby who is suffering from a severe form of MPOX in eastern Democratic Republic of Congo
The smallpox vaccine is known to help prevent MPOX because the two viruses are closely related.
In recent weeks alone, cases of the new strain have been detected in Sweden and Thailand, meaning it has now reached both Europe and Asia.
Although there are no confirmed cases in the UK yet, experts suspect the new variant is already in Britain as it can take more than two weeks for symptoms such as classic skin lesions to develop.
But experts have said the mortality rates of central African clade 1b are unlikely to be replicated in developed countries because of better access to higher quality healthcare.
The UK’s Health Security Agency has warned that it is “already making plans” for cases of the new strain in the UK.
Mpox normally cIt causes characteristic lumpy lesions, as well as fever, aches and fatigue.
In a small number of cases, it can enter the blood and lungs, as well as other parts of the body such as the brain, causing it to become potentially fatal.
