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EXPERT REACTION: Measles weakens your immune system for years

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If you haven't had the MMR vaccine, catching measles can cripple your immune system for years. Two separate studies examining the immune systems of unvaccinated children before and after measles infection found that the disease creates a kind of immune amnesia that leaves you more vulnerable to future viral and bacterial infections. Luckily, the vaccine prevents this immune amnesia and saves you from lots of other nasty bugs.

Journal/conference: Science

DOI: 10.1126/science.aay6485

Organisation/s: Harvard University, USA; Wellcome Sanger Institute, UK

Funder: This work was supported by a grant from the Value of Vaccine Research Network to S.J.E. and M.J.M.; a grant from the Gates Foundation to S.J.E.; an NIH/NIAID U24 grant to H.B.L. and S.J.E.; a grant from the European Union Seventh Framework Program (grant 202063) and a grant from the Academy of Finland (Centre of Excellence in Molecular Systems Immunology and Physiology; grant 250114) to M.K.; NIH R01 DK032493 to M.R.; NIH R21 AI095981 and R01 AI131228 to D.E.G.; and a grant from PREPARE Europe (EU FP7 grant 602525) to R.L.d.S. S.J.E. is an Investigator with the Howard Hughes Medical Institute.

Media Release

From: AAAS

In Unvaccinated Children, “Immune Amnesia” Occurs in the Wake of Measles Infection

Two separate investigations into the immune systems of 77 unvaccinated children before and after measles infection have revealed the infection can cripple immunity against viruses and bacteria for the long-term, creating a kind of “immune amnesia” that leaves individuals more vulnerable to future infections by other pathogens. Based on these findings, published in Science Immunology and Science, scientists emphasize once more the need for widespread vaccination, which may not only prevent measles, but may also prevent the weakening of “herd immunity” to other kinds of pathogens.

Before the introduction of the measles vaccine, nearly every child experienced measles infection. Vaccination has helped lead to an 80% reduction in measles cases between 2000 and 2017, saving an estimated 21.1 million lives. However, because of a combination of antivaccination campaigns, nonvaccinating religious communities, and limited access to the vaccine, measles continues to affect more than seven million people annually worldwide, causing upwards of 100,000 deaths. Reduced vaccination alone has led to a nearly 300% increase in measles infections since 2018. To help estimate the impact of vaccination, Velislava Petrova et al. and Michael Mina et al. investigated the hypothesis that measles can instigate immune suppression, which can persist for months to years even after the disappearance of visible symptoms, like the characteristic measles rash. This hypothesis has already been supported by previous studies, including evidence that associates measles with up to 50% of childhood deaths from infectious diseases. However, precisely how post-measles immune suppression unfolds in humans is unknown.

In Science Immunology, Petrova and colleagues sequenced antibodies produced by B cells – one of the primary immune cells able to recognize a virus and deploy attacks against it – from 77 unvaccinated children. The children ranged in age from four to 17 years old, did not have a history of natural measles and were from three Orthodox Protestant schools in the Netherlands. By comparing the children’s B cell data before and after measles infection, the researchers identified two indications of immune suppression from measles: incomplete restocking of the B cell pool and compromised immune memory due to depletion of B cell clones. In additional animal studies, the scientists found measles-infected ferrets already vaccinated against the flu became less immune to the virus and experienced more severe symptoms upon secondary flu infection.

In Science, Mina and colleagues used a tool called VirScan to analyze the responses of antibodies in the unvaccinated children before and after measles infection. The technology tracks antibodies to thousands of viral and microbial antigens in the blood. The researchers found that the disease wiped out 11 to 73% of the antibody repertoire across individuals two months after measles infection, severely compromising immune memory of various infectious agents even after recovery. Antibody depletion was not observed in infants vaccinated against measles, mumps and rubella. Furthermore, in measles-infected macaques, 60% of the antibody repertoire was undetectable for at least five months. Though rebuilding the antibody repertoire is possible through reexposure to the pathogens, this could take months or years and might pose several health risks, the authors say. A related Focus by Duane Wesemann describes both studies in further detail.

Attachments:

  • AAAS
    Web page
    Paper in Science. The URL will go live after the embargo ends
  • AAAS
    Web page
    Related report in Science Immunology. The URL will go live once the embargo ends.

Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Professor Raina MacIntyre is Head of the Biosecurity Research Program at the Kirby Institute from the University of New South Wales (UNSW)

This research strengthens the evidence that measles infection cripples the immune system even after recovery from measles. Specifically, the ability of the body to produce antibodies to any infections (not just measles) is impaired.

This means people who get measles are at increased risk of other infections after they recover from measles.

At a time when measles is on the rise worldwide, with the UK and other European countries losing WHO elimination status for measles in August this year, the risk of measles is higher than it has been in a long time.

It is critical that high levels of infant vaccination are maintained, and that travellers seek vaccination advice before they travel.

If adults are unsure of their vaccination status, it is recommended to get vaccinated.

The risks of being unvaccinated are not only that of measles, which is a potentially fatal infection, but also other infections because of the effect it has on the immune system.

Last updated: 31 Oct 2019 12:48pm
Declared conflicts of interest:
None declared.
Dr Roger Lord is a lecturer (Medical Sciences) with the Faculty of Health Sciences at The Australian Catholic University and Research Fellow with The Prince Charles Hospital (Brisbane).

Measles is a highly contagious viral infection which can cause potentially serious fatal complications in unvaccinated individuals. Overseas travel by unvaccinated individuals is commonly associated with outbreaks.

Eight recent cases involving airline passengers believed to be infectious between 8th-16th October 2019 have been reported by Queensland Health and the number has risen to 19 as the infection spreads.
 
Viral transmission is by secretions from the nose or mouth of an infected person several days before or after the development of a rash. 

Progression of the infection is associated with high fever and may include complications such as pneumonia, encephalitis, transient hepatitis and bacterial super-infection.
 
Severe measles associated bacterial infection is linked to a transient suppression of the immune system from the viral infection. 

The recent publications in Science Immunology and Science by Velislava Petrova et al. and Michael Mina et al. are significant to our further understanding of the immunological mechanisms involved in this immune suppression and importance of vaccination.
 
Treatment for measles once acquired is largely only supportive care so vaccination to prevent spread of the disease of the utmost importance.

Additionally, while prevention is better than cure understanding the process behind measles associated immune suppression will improve treatment options for infected individuals.

Last updated: 31 Oct 2019 12:47pm
Declared conflicts of interest:
None declared.
Professor Nikolai Petrovsky is from the College of Medicine and Public Health at Flinders University

For some time it has been recognised that many viruses have evolved particular tricks to actively block or suppress the human immune system, when infecting an individual, thereby ensuring the virus is able to replicate and shed for long enough to infect other individuals before the immune system gets the upper hand and is hopefully able to control and defeat the virus.

This immune suppression caused by the virus can in some cases last much longer than the infection itself, with individuals infected by the influenza virus showing evidence of impaired immunity and susceptibility to other respiratory tract infections for weeks or even months following the initial influenza infection.

Traditionally this immune suppression caused by viruses was mainly thought to act via suppression of the innate immune system, as well as by paralysis of T cells within the adaptive immune system.

What is particularly surprising in this work is that measles infection is shown to be able to deplete already existing memory B cell and antibodies already present in the individual, part of the adaptive immune system previously thought to be relatively resilient against viral attack.

Nevertheless, it was known that the measles virus receptor CD150/SLAMF1 is highly expressed on memory T, B, and plasma cells, resulting in their infection by the measles virus and subsequent depletion, explaining how measles virus is able to disarm adaptive immune memory.

This study characterised the antibodies in individuals before or after measles infection or vaccination and showed that measles infection but not measles vaccination was able to specifically depleted memory antibody responses against a broad range of other pathogens, thereby potentially leaving individuals recovering from measles infection vulnerable to many other infections, to which they would otherwise have been protected.

This study yet again dispels the dangerous 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.

This terrible misinformation has been used to justify not just refusals of parents to vaccinate their children but even the shocking practice where parents have infection parties where children are deliberately exposed to other children with measles or other viral infections in order to deliberately infect them.

Such practices should clearly be globally outlawed and parents subjecting their children to deliberate infection should arguably be faced with criminal charges as should any practitioners advocating or supporting such misguided behaviour. 

Not only does this study highlight the stupidity of such practices, but also the extreme dangers posed.

Not only does natural infection expose the children to the potentially devastating consequences of measles infection, but also as highlighted here, will weaken rather than strengthen their immune systems, so that even if they are lucky enough to escape serious consequences of the primary infection, they are still left prone to catching other infections due to the long term immune suppression mediated by the primary infection.

This almost certainly explains the reason for community studies showing individuals infected with measles have an increased rate of increased sickness and death for up to 5 years after their infection when compared to individuals that have not had measles infection.

This immune suppression is not apparent in those vaccinated against measles, who are thereby protected both against the risk of a serious measles infection that could otherwise cause permanent disability or even death, but will also be protected against the long-term immune suppression caused by the measles infection.

Almost certainly, the same situation applies to other vaccine-preventable viruses such as influenza, once again emphasising the importance of adequate vaccination to protect the community against the harmful primary and secondary consequences of infection by such viruses.

Last updated: 31 Oct 2019 12:46pm
Declared conflicts of interest:
Nikolai has declared that he is Research Director for Vaxine Pty Ltd

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