It's long been known that contracting measles weakens the immune system for weeks or months, putting people, especially children, at increased risk for potentially fatal infection by a host of germs.
Now, scientists find that this vulnerable period goes on much longer than thought, up to three years. So the benefit of avoiding measles also extends longer than was appreciated. Researchers also found that measles vaccination campaigns were followed by a drop in deaths for other infectious diseases.
Experts said the work is a wake-up call to parents who don't vaccinate their children out of unfounded fears about a link between vaccines and autism.
"The message is clear," said Dr. Richard Wenzel, an infectious disease specialist at Virginia Commonwealth University who was not involved in the study. Not only is the vaccine safe and effective against measles, he said, but it may also save a child's life by helping to guard against other infections.
Debate about the measles vaccine came into focus this year after a large outbreak tied to Disneyland sickened 147 people in the U.S., including 131 in California. Infections also spread to Mexico and Canada where 159 people fell ill in Quebec. Many stricken with measles were not immunized because of personal reasons or their age.
Measles, marked by fever, cough and a blotchy rash, has been eliminated in the U.S. for more than a decade thanks to an aggressive vaccination effort. Outbreaks still crop up when Americans or foreign visitors become infected overseas and spread the virus among populations that are not vaccinated.
In the latest study, an international team of researchers analyzed measles cases and death rates from other infections before and after widespread measles vaccination campaigns in the U.S., England and Wales, and Denmark.
After vaccinations, measles cases declined in all the countries. Deaths from non-measles infections also dropped. In the U.S., deaths from infections such as respiratory or diarrheal disease fell from 18 per 100,000 before vaccination to 6 per 100,000 after vaccination. Researchers attribute the drop to fewer measles cases caused by the introduction of the vaccine.
Using mathematical modeling, the team also found it took two to three years after getting measles for the immune system to rebuild itself.
The study, released Thursday by the journal Science, was funded by the Bill and Melinda Gates Foundation and federal grants.
By preventing measles, "you preserve your ability to fight off all of these other infections," said Michael Mina, a medical student at Emory University who led the study while at Princeton University.
While vaccination played a role, other factors such as better nutrition and smaller family size may also explain the drop in non-measles infections, said Dr. James Cherry, a pediatric infectious disease expert at the University of California, Los Angeles, who had no role in the study.
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