Measles can cause long-term damage to the immune system – resetting it to a baby-like state and leaving people vulnerable to other infections, scientists have said.
According to new research, the measles virus deletes part of the immune system’s memory, removing previous immunity to other infections in both humans and ferrets.
Scientists have dubbed the startling findings “immune amnesia.”
While the body is capable of rebuilding those defences, scientists say the process could take years.
With measles on the rise in the UK and in other countries across the world, Dr Michael Mina of Harvard’s school of public health said “it should be a scary phenomenon”.
Research from the Wellcome Sanger Institute, University of Amsterdam and their collaborators showed that the disease resets the human immune system to an immature state with only limited ability to respond to new infections.
Published in the journal Science Immunology, the study explains why children often catch other infectious diseases after measles.
The Harvard team analysed blood samples taken from 77 children before and after a measles outbreak in an unvaccinated community in the Netherlands.
They looked for antibodies, which remember viruses and bacteria they encounter to guard against a repeat infection.
After recovering from measles, the youngsters were left with plenty of antibodies against that virus – but ones they’d previously harboured against other germs had plummeted.
In the most severe cases, children were left “as vulnerable as if they were infants” said the study’s senior author Stephen Elledge, a Harvard geneticist.
A separate study, published Thursday in Science Immunology, supported the findings.
Scientists said the research has great implications for public health, as falling vaccination rates are resulting in rising cases of measles.
They said this in turn could cause an increase in cases of other dangerous infections such as flu, diphtheria or tuberculosis, even in people who were previously immune.
In the late 1960s a highly effective measles vaccine was introduced in the UK, and in 2017 the disease had been completely eliminated from the country.
However, measles is highly contagious and cases are rising again, with the UK’s vaccination uptake dropping below the required level of 95% of the population.
This led to the UK losing its World Health Organisation (WHO) measles elimination status in August.
In a separate study published in the Science journal, researchers used a tool called VirScan to analyse the responses of antibodies in 77 unvaccinated children aged four to 17 before and after measles infection.
The technology tracks antibodies to thousands of viral and microbial antigens in the blood.
Led by investigators at Harvard Medical School, Brigham and Women’s Hospital and the Harvard TH Chan School of Public Health, scientists found the disease wiped out 11% to 73% of the antibody repertoire across individuals two months after measles infection.
Professor Michael Mina said: “Imagine that your immunity against pathogens is like carrying around a book of photographs of criminals, and someone punched a bunch of holes in it.
“It would then be much harder to recognise that criminal if you saw them, especially if the holes are punched over important features for recognition, like the eyes or mouth.”
Prof Mina and colleagues found those who survive measles gradually regain their previous immunity to other viruses and bacteria as they get re-exposed to them.
However, because this process may take months to years, people remain vulnerable in the meantime to serious complications of those infections.