New research has shown that measles infection can cause part of the immune system memory to be deleted, taking away the body’s previously acquired immunity to other infections.

It is known that measles damages the immune system, as children infected with measles are more prone to other infections once they recover. Children can show immune suppression for five years after measles infection. However, the biological mechanisms behind this were not well understood.

Blood samples were taken from children both prior to and 40-50 days after infection of measles. The genes controlling antibody production in their naïve and memory T-cells were sequenced. It was found that specific memory cells that had been formed in response to previous infections were no longer present after measles infection.

The naïve B cells exhibited more features characteristic of immature immune cells after measles infection, meaning that they were now only able to make a limited selection of antibodies. Both symptoms are characteristic of ‘immunological amnesia,’ when the immune system forgets pathogens it has previously been exposed to. Therefore, if a measles patient was exposed to another infection after recovery, then their immune system would be less capable of mounting an immune response.

To investigate the ‘immunological amnesia’ further, ferrets who had been vaccinated with flu were infected with measles. The prevalence of anti-flu antibodies in their blood was reduced after infection, which meant that the previously vaccinated ferrets could now became infected with flu.

The study demonstrates the public health importance of the MMR (Measles, mumps and rubella) vaccine, even as global vaccination are falling. This is suspected to be due to multiple factors, including inaccurate information about vaccine safety spread on the internet by so called ‘anti-vaxxers.’ Social media companies and search engines have been criticised for allowing false information to spread easily. Many parents now are also too young to have experienced a preventable disease outbreak and do not appreciate the severity of diseases such as measles.

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