Why herd immunity matters: A fully immunized child contracts measles

According to numbers released last week by the CDC, there have now been 150 cases of Measles reported in the United States in 2015. This is part of the largest outbreak of Measles in the country since the disease was declared eliminated in 2000.

On Figure 1, our community of healthcare professionals sharing and discussing medical cases in real time, discussion of Measles and vaccination has increased in line with the outbreak. A pediatric physician using Figure 1 shared this expanded case with us as a learning opportunity for healthcare professionals on Figure 1 and the general public.

Known as @magicdoc on Figure 1, this pediatrician treated a child who contracted measles despite being fully vaccinated. The pediatrician works in a hospital near Disneyland, which is considered ground zero for this year’s outbreak in the United States. The child presented with a fever, conjunctivitis, and a maculopapular rash that started in his cheeks and spread down his body in a paint-bucket-type fashion.

Read the Q&A to learn more about this case, how Measles can be contracted even by those who are vaccinated, and why many Measles cases may be going unreported.

1. Why did you think to test for measles when this child was fully immunized?

We checked for measles because of his clinical presentation, fever, rash spreading from head down, and Koplik’s spots on the buccal mucosa. Our hospital is also located in California, where measles alerts have been pushed to providers at almost all institutions. He appeared to be having a less severe course because he was immunized, but the signs and symptoms were all there, so we decided to send off the tests.

2. How did you treat this patient?

Measles should be treated conservatively, so this child was sent home with instructions for supportive care and to remain isolated until the rash was gone. This patient also had a sibling under 12 months old who was brought in right away for Intramuscular immunoglobulin. Most cases of Measles can be treated at home with anti-pyretics as needed for fever and anti-itch products if needed for the rash. However, severe sequelae, such as pneumonia (6.5%) and encephalitis (0.1%), are possible. Mortality runs about 1:400.

3. Can you explain the concept of herd immunity and how it relates to this case?

Having first trained as a pediatrician and then as an ER physician, I have seen how important immunizations are, not only for the individual, but for the common good. Not everyone who receives a vaccine becomes fully immune, so the people who don’t become immune really rely on the majority being vaccinated to protect them from contracting an illness. Every time an outbreak has occurred in the United States, the immunization rate in the affected area has been below 90%.

4. In your opinion, are all cases of measles being reported?

There are a couple reasons that cases of the measles are not being reported. The first is that there’s a perception that testing for measles is cumbersome. This means that healthcare professionals aren’t sending samples to the health department, and they can’t report information that they don’t have. The second is that some pediatricians realize that it’s better to keep a child with measles isolated instead of bringing them to a public health center, so these cases treated at home aren’t being reported either.

5. What advice would you give to your colleagues in light of recent trends around immunization?

This is a time for all of us to be re-iterating the importance of vaccines. The one silver lining of these outbreaks is that they really bring home why vaccination is important. I have been using this as an example when I talk with parents about immunization. It illustrates the risks they take not only for their child but also for their community when they choose not to vaccinate.

View more discussion around Measles on Figure 1 here: Measles Discussion
*Originally posted on our blog on February 23, 2015