As measles cases spread around the world, scientists have discovered another danger of the disease: measles virus can wipe out the immune system, making people more susceptible to other diseases later. The study sheds new light on a virus that has been infected for centuries. The phenomenon is called "immune amnesia" and a new study published in Science documents how it works. The measles virus appears to erase the body's immune memory, destroying an average of 40 antibodies against other viruses and bacteria in a study created before the measles virus was struck. This means that people who suffer from measles are more susceptible to other diseases ̵
This new side effect is a complement to all other well-known symptoms of measles, such as rash, cough, fever and malaise. A mortem can also lead to serious complications – pneumonia, brain swelling – and even death. In 2017, measles killed 110,000 people worldwide and infected 6.7 million. About 1 in 5 non-vaccinated people in the United States who have measles have to be hospitalized, according to the Centers for Disease Control and Prevention. Immune amnesia helps to explain why the majority of deaths and complications are caused by infections that people acquire after measles.
"[Measles] not only destroys overall immune function in a few weeks as children recover from the virus, but it also prevents children from being able to protect themselves against pathogens that they should deal with in the long run," Michael Mina, an epidemiology assistant at Harvard TH Chan School of Public Health and a leading paper author, told Vox .
A study based on previous studies to suppress the measles immune system also has huge public health implications.
The rate of measles vaccine is decreasing worldwide, with measles cases trebling between 2018 and 2019, mainly due to problems with access to the vaccine or refusal of the vaccine. Several countries – including the United Kingdom of Kingston, Greece and Brazil – have recently lost their status to eliminate measles, meaning there have been outbreaks that have lasted more than a year. And this year the US is almost the same. So we're going back to measles vaccination, just as researchers are finding out how damaging the disease is to the immune system. Why is it even more important to get measles vaccine?
The measles virus is one of the most infectious diseases known to humans. Let's say a person with a cough in a room and leaves; hours later, if you are not vaccinated, you can catch the virus with tiny droplets in the air that the infected one left behind. No other virus can do this.
For anyone born before 1960, there is a high chance of having measles infection. They may have lived to talk about it, but they probably had friends who didn't. In the United States prior to the introduction of the vaccine in 1963, there were 4 million measles cases each year, resulting in 48,000 hospitalizations and 500 deaths.
The beauty of the vaccine is that most people who receive the right doses will never get measles, even if exposed. Until 2000, due to widespread vaccination, the virus was declared eliminated in the United States.
Researchers have long known that they have measles vaccination. And the side effects are rare and mostly very mild. But now they are aware that immunization is important for more reasons than they would appreciate.
For the study Science researchers tracked 77 non-immunized children in the Netherlands, part of a vaccine refusing the Orthodox Protestant community there. They took blood samples during a measles epidemic in 2013 (two months ago and after children became infected) and looked for changes in the children's immune system using VirScan, a tool that can measure blood levels of antibodies to hundreds of pathogens. They separately tracked five non-immunized children who did not contract the disease.
When researchers compared blood samples before and after measles, they found that the virus deleted between 11 and 73 percent of antibodies per child with an average loss of about 40 percent. They did not find the same effect in five children who had never become ill. And in a control group of children immunized with the measles, mumps, rubella (MMR) vaccine, they also found no loss of the immune system.
In another study published at the same time, in the journal Science Immunology researchers examined the same group of children, but instead focused on their B cells, a type of white blood cell that includes memory cells that produce antibodies in the body. Researchers have come to a similar conclusion: measles prepare the body for other diseases. In this case, the virus reduced the body's immune memory cells and returned the immune system to an immature, baby-like state.
"Studies show that measles is more dangerous than we think, and it can have consequences on our immune system long after the symptoms of measles have disappeared," says lead author of the second paper Velislava Petrova, a doctoral student at the Welcom Sanger Institute . The public health message, she added, is that getting MMR vaccination "is important not only for preventing measles disease but also for other secondary infections you may have if you have measles disease and your immune system is damaged. "
Perhaps this new study – coming at a time of measles resumption around the world – will encourage people on the vaccine fence to be immunized. "In an age in which people and even politicians have some kind of amnesia about how bad measles were," says Harvard Mina, "it makes it clear [it] that measles infection is not just a common benign childhood infection"