With all of the news about the measles (rubeola) in California (51 cases) and New York (25 cases), (we) pediatricians are also on the alert for any measles cases in our areas. I have written many times about the importance of vaccines, but this latest outbreak of measles is just a reminder of the importance of vaccines and the concept of herd immunity.
By maintaining high vaccine rates for all children (adults too), even those who may not have been vaccinated are protected because the "herd", in otherwords the largest group of children, has received the vaccine. It typically takes a 90-95% vaccination rate to maintain this herd immunity. Once the vaccination rate drops below this there is more likelihood to see a re-occurrence of a disease. In some areas of the country, where parents may choose to "opt out" of vaccines, the vaccination rates are below 90%. This is a critical situation.
Although measles was pronounced eliminated in the United States in 2000, measles is still widespread worldwide. With international travel an everyday occurrence it only takes one person to "import" measles into the United States. Measles is a very contagious disease and is spread by respiratory droplets. The virus can remain in a room for up to 2 hours after an infected person has been there!!! Viruses are smart and hardy. You would never know if you walked into a room or airplane after someone had just left who had measles. Remember, an infected person is contagious even before the measles rash appears. Measles symptoms may occur up to 3 weeks after exposure. The illness begins like many others with fever, runny nose, cough and red eyes. It takes several days and then the measles rash develops. By this time many others have likely been exposed.
There are certain children who cannot receive vaccines due to medical reasons. Those children are protected by all of the others who are vaccinated. Making sure that your own children are vaccinated is paramount. Measles vaccine, given as the MMR is typically given at the 12-15 month old visit and again between the ages of 4-6 years.
There has also been a great deal of confusion on social media sites about measles (rubeola) and exanthem subitum (roseola). These are different illnesses and measles IS a vaccine preventable disease, while roseola is not. More to come on roseola....