The MMR Vaccine

The MMR vaccine protects against 3 potentially dangerous viral infections: Measles, Mumps and Rubella. I want to focus on the diseases that this vaccine prevents because in North America, we do not see them very often thanks to immunization. However in developing countries where vaccines are not easily available, these infections and their complications are much more common.

Measles(Rubeola) is caused by the Measles virus which is highly contagious and spreads by droplet or direct contact with droplets from the nose, mouth and throat of an infected person or with articles that have come in contact with nasal or throat secretions. The incubation period or the time between contact and appearance of first symptoms, is 8-12 days. The initial symptoms of Measles include runny nose, red eyes and fever.  3 - 4 days later, a red rash develops on the face and spreads to the rest of the body. The rash is not usually itchy, and lasts 4 -7 days. People with Measles are contagious for 4 days before the onset of the rash and up to 4 days after its appearance. Serious complications include severe lung or brain infections. Those most susceptible to complications and death, include malnourished young children and persons with underlying immune weakness.

Mumps(epidemic parotitis) is caused by the Paramyxovirus. Spread through respiratory droplets, it infects the salivary (parotid) glands found in the neck region behind the lower jaw and below the ear. The incubation period is 14 - 24 days. The infected glands swell and a person with Mumps is contagious during the period between 1 day before the swelling begins and 3 days after the swelling resolves. There can be some low to moderate fever, and the swelling usually goes away within a week or so. However, there are some rare, yet potentially serious complications of Mumps, including meningitis and in older boys, infection of the testicles (orchitis) which can lead to future infertility

Rubella(German Measles) is caused by the Togaviridae virus and spread by respiratory droplets. After a 14-21 day incubation period, the infection starts with mild nonspecific, cold-like symptoms. After about 24 hours, a rash develops all over the body. People with Rubella are contagious from 1week before to 1 week after the rash appears. Rare complications of rubella include arthritis, infection of the nerves and in some extremely rare cases, chronic brain infections. Importantly, the Rubella virus can also be passed through the blood from an infected mother to her baby during pregnancy, referred to as congenital Rubella. Contracted this way, Rubella can cause significant and permanent damage to the unborn baby, especially if the infection occurs during early pregnancy. This is why pregnant mothers and women planning to become pregnant are routinely tested for evidence of past rubella infection or vaccination.

These infections have at least 3 things in common: They are all viruses, all can be prevented by a single vaccine and there is no specific treatment. So prevention is the best approach. The MMR vaccine simultaneously protects against all 3 of these infections and is usually administered at 12 months of age with a booster given between 4-5 years of age.

About the MMR vaccine

The MMR vacine is made up of the attenuated(weakend)viruses that have been inactivated so they can essentially trick the body into thinking it is the real infection. In turn, the body's immune system creates antibodies that protect it against the real viruses. The MMR vaccine is considered safe with very few side effects that include local reaction at the injection site. In rare cases, a Measles-like rash can develop within 7-14 days after the injection. This reaction, thought to be casued by the weakened live-vaccine-virus usually resolves on its own without any complications. It is impotrtat to stress that there is no scientific evidence linking MMR vaccine as the casue of autism.