Mumps Outbreaks in Canada and the United States: Time for New Thinking on Mumps Vaccines

Abstract

Mumps epidemics in Canada and the United States prompted us to review evidence for the effectiveness of 5 different vaccine strains. Early trials with the Jeryl Lynn vaccine strain demonstrated an efficacy of approximately 95%, but in epidemic conditions, the effectiveness has been as low as 62%; this is still considerably better than the effectiveness of another safe strain, Rubini (which has an effectiveness of close to 0% in epidemic conditions). The Urabe vaccine strain has an effectiveness of 54%-87% but is prone to cause aseptic meningitis. Little epidemiological information is available for other vaccines. The Leningrad-Zagreb vaccine strain, which is widely used in developing countries and costs a fraction of what vaccines cost in the developed world, seems to have encouraging results; in 1 study, the effectiveness of this vaccine exceeded 95%. Aseptic meningitis has also been reported in association with this vaccine, but the benign nature of the associated meningitis was shown recently in Croatia. Also, the Leningrad-3 strain seems to be effective but causes less-benign meningitis. No mumps vaccine equals the best vaccines in quality, but the virtually complete safety of some strains may not offset their low effectiveness. Epidemiological data are pivotal in mumps, because serological testing is subject to many interpretation problems.

Dynamics of the serologic response in vaccinated and unvaccinated mumps cases during an epidemic

“…2,3 Although it was assumed that mumps vaccination induces life-long protection, 4 several mumps outbreaks, especially among vaccinated student populations, have been reported during the last decade in various countries where mumps vaccination has been implemented into their national immunization programs. [5][6][7][8][9][10][11][12][13][14] In 2009-2012, a mumps epidemic (genotype G) arose that spread across multiple locations within the Netherlands, in which also primarily vaccinated students were affected. 15 Waning of vaccine-induced immunity has been suggested to play a role in these outbreaks.…”

“…15 Waning of vaccine-induced immunity has been suggested to play a role in these outbreaks. [6][7][8][9][10]13,14 When compared to the other components in the MMR vaccine, the mumps component seemed to be the least effective in eliciting good (high avidity) antibody responses, which were shown to wane to lower levels and in avidity index 20 y after a second MMR vaccination. 16 Furthermore, vaccine-induced antibody concentrations measured against a (heterologous) genotype G virus were shown to be approximately one half the concentrations measured against the vaccine strain (genotype A; Jeryl Lynn).…”

Outbreak-related mumps vaccine effectiveness among a cohort of children and of young adults in Germany 2011

“…21 These outbreaks had in common that they predominantly affected adolescents and young adults, and that a high proportion of cases were 2-times vaccinated. Several theories have been discussed to explain the age shift and the high proportion of vaccinated cases, such as waning immunity, lack of boosting due to decreased wild virus circulation after vaccine introduction, and mismatch between wild and vaccine virus.…”

Horizontal transmission of the Leningrad–Zagreb mumps vaccine strain: A report of three cases

“…L-Z, originating from the Russian Leningrad-3 vaccine strain, has been successfully used in other parts of the former Yugoslavia, as well as in some of the developing countries (1,10). L-Z is a very immunogenic and efficacious strain, but even serious adverse reactions (e.g.…”

“…L-Z is a very immunogenic and efficacious strain, but even serious adverse reactions (e.g. aseptic meningitis), especially after primovaccination have been reported (9,10,11,12).…”