Is measles considered contagious?

Measles is considered highly contagious due to the nature of its transmission and the characteristics of the virus. When an infected person coughs or sneezes, they release respiratory droplets that can remain in the air or on surfaces for up to two hours. Anyone who is not immune can easily contract the virus by breathing in these droplets or by touching contaminated surfaces and then touching their face, particularly the mouth or nose.

The contagious period for measles starts from about four days before the rash appears and lasts until about four days after the rash develops. This wide window of contagiousness increases the likelihood of outbreaks, especially in populations with low vaccination coverage. In fact, the overall transmission rate of measles is one of the highest among vaccine-preventable diseases, with an estimated reproduction number (R0) of 12 to 18, meaning each infected person can potentially infect many others.

Understanding the highly contagious nature of measles underscores the importance of vaccination programs and public health measures to prevent outbreaks and protect those who are most vulnerable, such as infants and individuals with compromised immune systems.