Measles vaccine immune escape: Should we be concerned?

Excerpt

Introductions of measles containing vaccines, initially in the United States in 1963, the United Kingdom in 1968, and globally thereafter have caused measles cases to plunge worldwide over the past half-century [1]. By any metric, the measles vaccine is among the most successful public health interventions of modern times and is directly responsible for the near elimination of the virus in much of the world—an incredible achievement for a pathogen that only 50 years ago infected almost every child born. It is estimated that since the year 2000, the measles vaccine has prevented over 21 million deaths from acute measles virus infections globally [2]. Furthermore, new ecological and immunological evidence suggests that this number could be far greater—by preventing measles-associated long-term “immunological-amnesia” [3, 4]. However, despite the magnificent successes of the global measles vaccine program, including a declaration of measles elimination in the Americas that persisted through much of the 2000s [5, 6], millions of measles cases continue to occur each year, primarily in Africa, but increasingly in Europe, Asia, and the Americas. In the past year, four nations (UK, Brazil, Greece, and Venezuela) lost World Health Organization (WHO) measles elimination status and the United States is teetering on the brink of losing this status [7]. So far in 2019, worldwide reported measles cases have nearly tripled compared to the same point in 2018 and overall are the highest they have been since 2006. In the US, the number of cases is the highest it has been in over 25 years [7]. …