Northwestern University infectious disease expert Dr. Tina Tan said it's likely the measles outbreak in West Texas and on the border of New Mexico will continue to spread due to a large unvaccinated population that is highly susceptible to "one of the most contagious viruses."
"The most important thing that people need to understand is that measles is a viral disease that is very contagious," said Tan, professor of pediatric infectious diseases at Northwestern University Feinberg School of Medicine and an infectious disease physician at Ann & Robert H. Lurie Children's Hospital of Chicago. "The vaccine is our best tool to protect individuals against measles."
Dr. Tan, also the president of the Infectious Diseases Society of America, is available to speak to media about the rise in cases, efficacy of newly suggested treatment options, appropriate childhood vaccination schedules, the severity of the disease and waning herd immunity. Contact Kristin Samuelson to schedule an interview.
In the Q&A below, Dr. Tan highlights some of the most alarming and misunderstood facts about the virus:
Exactly how contagious are the measles?
Dr. Tina Tan: It's one of the most contagious viruses with an R0 ("R naught") anywhere form 11-18. That means if a person with measles is among individuals who are susceptible, they can infect up to 18 individuals. If they're in the same house with susceptible individuals, they can transmit it to 90% of susceptible household members.
Some are suggesting treatment options such as clindamycin, cod liver oil and vitamin A. How effective are those?
Tan: Clindamycin is an antibiotic, and antibiotics do not work against viruses. There are no antivirals that are licensed for treatments against measles. As for cod liver oil, there's absolutely no indication at all that cod liver oil has any effect on measles. And as for vitamin A, it's not a treatment, but in low-and middle-income countries where individuals might be malnourished and have low vitamin A levels, they can take vitamin A to help decrease the severity of the measles infection. If you're in the U.S. and are hospitalized, measles can further deplete your vitamin A levels, so taking vitamin A is a way to help patients feel better faster. But they can only receive two doses and those doses are age dependent and really only given for infants and young children.
How does the measles present in patients?
Tan: What most people don't understand is measles is not just a rash. It starts with fever, cough, runny nose, and conjunctivitis followed by the development of the rash. Measles has a lot of other complications that can be associated with it. You can get ear infections, pneumonia, croup, diarrhea, encephalitis (inflammation of the brain) that often results in permanent brain damage. It is not a benign disease. People with measles can get very, very ill. They can lose their hearing or go blind.
What is the typical childhood immunization schedule for measles?
Tan: If you were born after 1957 and you received two appropriate vaccines (those created after 1969) that are appropriately spaced, then you are protected for life. The appropriate spacing recommended by the American Academy of Pediatrics and the CDC is the first vaccination at 12 to 15 months of age and the second dose at 4 to 6 years old. If you need to accelerate things, an infant can get the second dose anywhere from 28-30 days after the first dose. If the mother is vaccinated, the baby will have antibodies in their first year of life. However, for those whose moms have never been vaccinated, they wouldn't have that protection.
If someone is not vaccinated and has been exposed, what can they do?
Tan: If someone who is unvaccinated has been exposed, they can still get vaccinated within 72 hours of the exposure to protect them from developing measles. For those who can't receive vaccination because they're too young, are immunocompromised or are pregnant, they can receive intramuscular or intravenous immunoglobulin within six days of exposure. This provides passive immunity for those who have been exposed. The CDC have recommended infants 6 to 11 months of age get a measles vaccine to protect them, but that wouldn't count for the two recommended doses.
Why not?
Tan: An infant's immune system is not mature enough before 1 year old to make it be optimal for that first dose.
Should we be worried about waning herd immunity?
Tan: Yes. That's what protects the very young infants and the other people in the population who can't receive vaccines. There are so many immunocompromised people in the population who can't receive it and they rely on herd immunity to be protected. With measles, you need 95% herd immunity rate to protect these people.
