need an additional third vaccine in 3 - 4 weeks. (marvistavet.com)
Mumps outbreaks are also on the rise in the United States, to the point that the CDC is contemplating a third vaccine dose, according to The Washington Post. (romper.com)
In 1960, both the Sabin vaccine and a third vaccine, developed by Jonas Salk, were found to be contaminated with SV40, a monkey virus which is nothing like HIV. (newscientist.com)