Mumps outbreaks in Canada and the United States: time for new thinking on mumps vaccines

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.

Mumps outbreak in young adults following a village festival in the Navarra region, Spain, August 2006

On 10 August 2006, 12 cases of mumps were notified from a village of around 3500 inhabitants in Navarra, northern Spain. In 2005, the Public Health Institute of Navarra

Comparison of the effectiveness of two mumps vaccines during an outbreak in Switzerland in 1999 and 2000: a case-cohort study

In two recent nation-wide outbreaks of mumps in Switzerland two-thirds of young children with clinical mumps had a history of primary vaccination. On average, measles-mumps-rubella (MMR) vaccination coverage is 80%. Two types of vaccine are commonly used: Jeryl-Lynn and Rubini. The effectiveness of the latter has been questioned in several publications. The authors therefore compared Rubini to Jeryl-Lynn in a case-cohort study. The study included 111 young children with clinical mumps who had been reported to the Swiss Federal Office of Public Health (SFOPH) by primary care physicians of the Swiss Sentinel Surveillance Network (SSSN) between January 1999 and May 2000. Sentinel physicians also sampled 661 children from the same birth cohort as the cases. While we found no evidence for the effectiveness of the Rubini strain, vaccination with the Jeryl-Lynn strain was 70% effective against clinical mumps. Furthermore, children vaccinated with the Rubini strain attended primary health care more frequently with clinical mumps than those who had received Jeryl-Lynn (odds ratio: 2.4; 95% confidence interval (CI): 1.3, 4.7). Restricting the analysis to laboratory confirmed cases increased the odds ratio to 18.4 (95% CI: 2.5, 811.2). Our study confirms the low effectiveness of the Rubini strain vaccine in the field. This vaccine should therefore be considered inappropriate for the control and elimination of mumps and its use should be discontinued. As other vaccines with comparable quality and safety standards and a substantially higher effectiveness are available the MMR vaccination program in Switzerland will not be compromised if the use of Rubini is no longer recommended.

Detection of mumps virus genome directly from clinical samples and a simple method for genetic differentiation of the Hoshino vaccine strain from wild strains of mumps virus

A simple and sensitive method was developed for the differentiation of the Hoshino vaccine strain from wild strains with a restriction fragment length polymorphism (RFLP) analysis in the part of hemagglutinin-neuraminidase (HN) gene. The virus genome was amplified by using a reverse transcriptase-polymerase chain reaction (RT-PCR) directly from clinical samples. The PCR product of the Hoshino vaccine strain was cleaved into 2 fragments after digestion with Sca I and Afl II. All wild strains showed 2 RFLP profiles, A and B, different from that of vaccine strain. Wild A strains were cut into 2 fragments after digestion with Sca I only, while wild B strains were cleaved neither with Sca I nor Afl II. This molecular approach provides an effective method for differentiation of the Hoshino vaccine strain from wild strains of mumps virus in patients after vaccination.