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The number of measles cases in the U.S. continues to climb, reaching 1,408 this year — the highest number on record in more than three decades, according to data from the Centers for Disease Control and Prevention (CDC).
The vast majority (92 percent) of these cases have occurred in unvaccinated individuals or people of unknown vaccine status. Roughly 176 people have been hospitalized with the vaccine-preventable illness, and three have died.
Here are five things you need to know about the current situation, including vaccine advice for older adults.
1. Measles is highly contagious
If the current tally of cases doesn’t seem particularly alarming, know that “even one case of measles is something that we should all sit up and pay attention to,” says Patricia A. Stinchfield, a nurse practitioner and immediate past-president of the National Foundation for Infectious Diseases. “And the reason for that is, it is the most contagious and easily transmissible virus that we have.”
Like many other viruses, measles spreads through droplets released into the air when an infected person coughs or sneezes.
But unlike other common viruses, measles is so contagious that up to 90 percent of people who are close to an infected person will become infected if they are not immune to the virus, according to the CDC.
“It doesn’t have to be a cough right in your face,” Stinchfield says. Tiny virus particles can survive in the air for two hours, where they “circulate around and bounce over to this person and that person, and before you know it, you’ve exposed a lot of people,” she says.
What’s more, a person infected with measles can spread the virus four days before the most obvious symptom — a telltale rash — appears, and for four days after.
2. Many older adults have immunity — but some may need the vaccine
With the current outbreak, you might be wondering: Do I need the measles vaccine?
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