Vaccine protection against mpox ‘fading’, warns study – as cases start creeping up before ‘summer celebrations’
MPOX cases are continuing to spread because protection from vaccines is fading, a study suggests.
Tens of thousands of Brits were jabbed against the virus — previously known as monkeypox — after an outbreak in the summer 2022.
But immunity from the vaccine may already be at zero, Swedish researchers suggested.
It means booster doses - and more widespread vaccination - may be needed in order to prevent another surge.
The vaccination programme in the UK ended in July 2023.
Cases of mpox are currently double the number seen this time last year in the US, according to the Centers for Disease Control and Protection (CDC).
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Dr Klara Sonden, of the Public Health Agency of Sweden, said: “Our results indicate a rapid decline in neutralising antibodies after two doses.
“These results, together with the continued spread of mpox in Europe, has prompted the consideration of a booster dose.
“Long-term protective immunity might need a booster dose for its maintenance.”
Mpox causes a blistering rash, a high temperature, headache, muscle aches, backache, swollen glands, shivering, exhaustion and joint pain.
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The global mpox outbreak exploded two years ago, with more than 30,000 cases in the US and 3,500 in the UK getting infected.
The virus was particularly prevalent in gay and bisexual men and it killed three people in the UK and 32 in the US.
The disease was declared no longer a public health emergency in the US last year, with cases dipping thanks to a mass vaccination scheme.
However, latest CDC data show some 570 cases have been detected in the US so far this year — twice the number at the same point in 2023.
Health officials last week issued a warning that cases are increasing in Virginia, with four patients hospitalised since the start of the year.
Dr Brandy Darby, of the Virginia Department of Health, told : “We felt like it was really important to get the word out that there is a continued risk from this virus. It's still here.
“We also wanted to give people time to protect themselves ahead of Pride season.
"We're hoping this might encourage people to go ahead and get vaccinated so they can go out and enjoy their celebrations and not have to worry so much about mpox."
Mpox is a virus that is more common in west or central Africa and is spread by physical contact with mpox blisters or scabs, including during sexual contact.
Touching clothing, bedding or towels used by someone with mpox and the coughs or sneezes of a person with mpox when they're close to you can also spread it.
'No antibodies after a month'
The latest study, which will be presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases in Barcelona, looked at how strong immunity is now.
Researchers looked at data from 100 men who visited a sexual health clinic in Stockholm in 2022.
They tested their blood before their first dose of a MVA vaccine, before their second dose, 28 days after their second dose, and three months after their second dose.
The MVA vaccine is a version of the smallpox vaccine. It was offered to those most at risk people in the UK in the summer of 2022, including gay, bisexual and other men who have sex with men.
The study found disease-fighting antibodies fell within a year of vaccination, and to zero within the first few months if the patients hadn't had a smallpox vaccine previously.
Some 67 of the 100 tested were certain they had never had a smallpox vaccine before - the jab was de-escalated globally in the 1970s after the disease was eliminated.
The study said among those without prior smallpox vaccination, fewer than half of the group showed any detectable antibodies at all 28 days after the second vaccination.
Dr Sonden said: “Our findings corroborate other studies showing that mpox vaccination results in neutralising antibodies only in a proportion of vaccinees.
“A significant decline occurs already during the first month post-vaccination.
“Immunity after previous MPXV infection mounts a higher and more robust neutralising response. In conclusion, the findings merits the study of booster doses.”
The researchers were backed by another team in Austria, who have reported a breakthrough case in a man who has had two doses of the vaccine.
A 35-year-old was fully vaccinated in November 2022, but fell unwell with mpox in January 2024 - even more severe than those unvaccinated, the Public Health Authority in Vienna stated.
A second breakthrough case reported in March 2024 is under investigation.
The MVA vaccine was originally given as one dose to those most at-risk in the UK due to a shortage.
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But now, the second dose is offered around three months after the first.
The NHS mpox outbreak vaccination programme ended in July 2023. But it is still available in London and Greater Manchester to eligible people.
What are the symptoms of monkeypox?
The first symptoms of monkeypox include:
- A high temperature
- A headache
- Muscle aches
- Backache
- Swollen glands
- Shivering (chills)
- Exhaustion
- Joint pain
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