In light of recent measles outbreaks in the US, would you recommend an MMR booster for immunocompetent patients born before 1957?

I would not recommend a measles vaccine for a person born before 1957. This year has been chosen because people before born before 1957 have a very very high likelihood of having had measles because virtually all children got this highly contagious disease. On the other hand, there is no harm to getting a MMR vaccine so if a person is particularly nervous, they can certainly get one. But as mentioned I would not recommend the need to do so.

I think titers are useful. Would revaccinate if not at protective levels.

Low antibody titers in these patients do not mean that they do not have adequate memory B cell responses to develop neutralizing antibodies upon new natural exposures. If the individual has a comorbidity that is known to compromise immunity, a vaccine could be considered. Again, looking at the epidemiology data for this, it does not appear that there is a substantial risk of infection even in this population.

More of a question -

What about those born between 1963-1968, have not received a booster, and are not sure if they received the attenuated or inactivated measles vaccine?

It is my understanding that the inactivated measles vaccine was still available during this period and was not very effective.

SMS

Currently, I would not recommend a booster for all immunocompetent individuals born before 1957. However, for healthcare workers, it's recommended that they have proof of immunity. If they do not have this already, I would check titers and revaccinate if not immune.

The question is very appropriate and, unfortunately, there are no good trials (that I am familiar with) that look at effects of measles vaccine in altering immune parameters and enhancing protection in people who have not had MMR but did have the measles infection. So it begs the question of risk-benefit. The risk of getting the measles vaccine is relatively limited unless the individual has a robust anti measles antibody titer which could, in theory, increase risk for immune complex disease. The potential benefit could be to not only provide protection against a new measles virus infection but to prevent the complication of "immune amnesia" that has been proposed as a reason for post infectious susceptibility to other infectious diseases. ...