Measles (also called rubeola) is one of the most infectious diseases in the world. Infectiousness of a disease is measured by something called R₀ (basic reproduction number). This is a measure of how many people will be infected by one person with the disease in an un-immunized population. For measles R₀ ranges from 12-18. That means in an un-immunized population, 1 person with measles will on average infect 12 or more others. To put this in perspective The R₀ for influenza is 0.9-2.1. The R₀ for Ebola is 1.9. The R₀ of COVID19 is 1.4-2.4. You can see that the infectivity of the measles virus is as much as ten times higher than other diseases that we consider very infectious.

Measles Vaccine

The recommended two doses of measles vaccine offers lifetime 97% protection against being infected with measles. The measles vaccine is a live vaccine. This means that it is a form of measles virus that has been weakened (attenuated) so that it will not cause infection in people with normal immune systems. It cannot be given, however to people with weak immune systems, such as people on chemotherapy for cancer. It also cannot be given to infants younger than 6 months because their immune systems are not developed enough for a live virus vaccine. 1 dose of MMR vaccine can be given to infants at least 6 months old if they are going to travel to a country where measles is still endemic. This offers some protection, but they still need two doses of the MMR vaccine after age 1. The recommended age for the first dose of the measles vaccine is 1 year. The second dose is usually given at age 5 or 6. Even the first dose gives 93% protection against being infected with measles.

People who cannot get the measles vaccine are protected by all those people who do get the vaccine. This is called herd immunity. If enough of the population has been vaccinated then there is no transmission of measles even to those people who can’t take the vaccine. Outbreaks of measles are unlikely to happen if at least 90% of the population has been vaccinated. The lower the vaccination rate below 90%, the more likely measles outbreaks will occur in unvaccinated people. In Gaines county, Texas, where the current measles outbreak started, the measles vaccination rate was 75%.

Is the measles vaccine safe?

The measles vaccine is given in combination with mumps and rubella (German measles) vaccines. Reactions are not common but some children get a sore arm and/or a mild fever. One in three thousand children will have a febrile seizure. Although a febrile seizure is very scary for parents, a febrile seizure is not life threatening and never happens again unless the child already has an underlying seizure disorder. An even smaller number of children have an allergic reaction to the MMR vaccine. An allergic reaction is a rare complication of any vaccine. About one in 40,000 children can get a low platelet count. This usually resolves on its own and rarely requires treatment.

How dangerous is measles?

Measles can cause pneumonia and encephalitis (inflammation of the brain) particularly in un-immunized children under 5. About one in five children (or adults) with measles have to be hospitalized. Up to two children per thousand cases die from complications of measles. There is a rare but always fatal inflammation of the brain that can occur up to 7 years after having had measles. It is called subacute sclerosing pan encephalitis (SSPE). When immunization rates in the US were above 90% SSPE disappeared. Unfortunately with the current US outbreaks we may see it again.

In the 10 years before the measles vaccine was available nearly all children got measles by the time they were 15 years old. It is estimated 3 to 4 million people in the United States were infected each year. Among reported measles cases each year, an estimated 175,000 developed pneumonia; 48,000 were hospitalized; 1,000 suffered encephalitis (swelling of the brain); 400 to 500 people died.

As of March 7 the current outbreak in Texas and New Mexico is up to 208 cases, 198 in Texas and 10 in New Mexico. Twenty-three children have been hospitalized. There have already been two deaths in this outbreak, one in Texas and one in New Mexico.

Recommendations

If you were born before 1957 then you have had measles and are already immune. You don’t need vaccination. If you were born after 1957 and you have never had measles vaccine, then you and your children (if they are also un-immunized) should go to your pharmacy or health department and get vaccinated immediately. The risk of measles infection is much much higher than the rare adverse effects of the MMR vaccine. If your child has already had two doses of MMR vaccine after age 1 then he/she does not need to be re-vaccinated.

From 1963 until 1967 an inactivated measles vaccine was used in the US. This vaccine did not give long lasting immunity. If you were vaccinated between those years, you should get at least one MMR booster. From 1963 to 1989 only on MMR vaccine was recommended. If you were vaccinated between those years you should get a booster MMR if you live in an area with a low vaccination rate or if you are planning international travel. After 1989 two vaccinations were recommended. If you were vaccinated after 1989 you don’t need a booster.

Treatment of Measles

Once a child gets measles, there is no treatment other than supportive therapy. There are no antiviral drugs that work against the measles. Virus. Robert F Kennedy Jr, unfortunately now head of HHS, has stated that getting measles vaccine is a personal decision. While that is technically true, nothing else prevents or treats measles. Kennedy has suggested that vitamin A and Cod liver oil can be used to treat measles. There is absolutely no evidence for this and furthermore too much vitamin A can be toxic.

Bottom Line

Measles can be a deadly disease, especially for children under 5. The MMR vaccine is safe and serious reactions are very rare. Two doses of measles vaccine after age 1 gives lifetime 97% immunity to measles. There is no anti-viral medicine that treats measles. Vitamin A and cod liver oil do not work and too much vitamin A can be toxic.