The discoveries additionally fill in as an update that the current year's record-breaking measles flare-ups in the USA will have waiting impacts, Schaffner included.
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". The paper pairs with another published today in Science Immunology.
The global team, which includes the Wellcome Sanger Institute, the University of Amsterdam and Imperial College London, revealed that the measles virus deletes part of the immune system's memory, removing previously existing immunity to other infections, in both humans and ferrets. "If you don't vaccinate your kid against measles, not only the kid may get infected - and it's not a pleasant or mild infection, it has a number of potential consequences in the brain and heart and other organs - but also the infection lowers the immunity to all of the previous viruses and bacteria that this kid has been exposed to".
One possible explanation was that the measles vaccine boosted a child's overall immune system.
Modern genetic techniques now revealed which immune cells in particular were wiped out by the measles virus, researcher Colin Russell of Amsterdam UMC explained to Trouw.
"This [measles-induced immune amnesia] has never been characterized to the extent that they've done here", says Mark Slifka, an immunologist at Oregon Health & Science University in Portland.
The discovery that measles depletes people's antibody repertoires, partially obliterating immune memory to most previously encountered pathogens, supports the immune amnesia hypothesis. Parents in that community do not vaccinate on religious grounds but were willing to participate in a research study about the virus. This test was repeated in macaque monkeys before and up to five months after infection. However, precisely how post-measles immune suppression unfolds in humans is unknown. The average time between sample collections was 10 weeks. The new studies published this week in the journals Science and Science Immunology provide substance to what has been the leading theory: Measles can damage the immune system by erasing the body's memory of previously encountered antigens. During infection, people have fewer white blood cells, which protect the body against disease, and this is seen in the clinic as a low white blood cell count. B-cells keep building these antibodies even after the pathogen clears, so the body "remembers" the disease if it ever returns. According to this theory, the virus can damage the body's immune memory, causing the so-called immune amnesia. However, it's unclear how effective the new "soldiers" are at fighting off specific infections - that may be a question for future studies, Wesemann said.
Antibodies are a key component of the immune system and are produced by B cells. In the new paper, Mina, Elledge, and colleagues used a tool Elledge's lab developed - called VirScan - which actually detects thousands of types of antibodies and their targets. Even the US, where most children are immunized, has seen a resurgence fueled by outbreaks in unvaccinated communities that in turn threaten people too young or sick to be immunized. Experiments in animals have also suggested the measles virus impairs immunity. The kids' other antibodies seemed to be disappearing.
The measles vaccine protects the immune system's memory from being deleted by the virus in the first place - and if a patient gets measles, they may want to get booster shots for all their previous vaccines, like hepatitis and polio, to mitigate the effects of immune amnesia, said the Harvard Medical School press release.
"This study yet again dispels the risky myths perpetuated by homeopaths and other "natural" healers who claim that exposure of infants to natural infection is important to "strengthen" children's immune systems", writes endocrinologist Nikolai Petrovsky from Flinders University.
In the wake of contracting the infection, youngsters lost somewhere in the range of 11% and 72% of their antibody diversity, showing that measles had incompletely cleaned their invulnerable memory. The researchers found that all these kids either lived together or in the same neighborhoods, which expedited the pathogens' spread.