Third Dose of MMR Vaccine Could Boost Protection Against Mumps

A third dose of the measles, mumps, rubella (MMR-3) vaccine may help protect young adults at risk from waning immunity to mumps, according to a recent study in the Netherlands.

The study, published in The Journal of Infectious Diseases, evaluated IgG and virus-neutralizing (FRNT) antibody responses against the mumps Jeryl Lynn vaccine and the G outbreak strain at 4 weeks and 1 year after MMR-3.

“A third dose of measles-mumps-rubella vaccination increased antibody levels that may protect against mumps infection for up to 1 year, which is longer than previously assumed,” Patricia Kaaijk, PhD, with the Centre for Infectious Disease Control at the National Institute for Public Health and the Environment in the Netherlands, told Contagion^®. “Antibodies increased 1 month after vaccination and although antibody levels declined 1 year later, the antibody levels were still significantly higher than before vaccination.”

At 4 weeks, levels increased by a factor of 1.65 for IgG, 1.34 for JL/FRNT, and 1.35 G/FRNT. At 1 year, those numbers were 1.37, 1.15, 1.27.

Although the MMR vaccine has dramatically reduced the incidence of mumps, outbreaks of the disease have been reported in several countries among vaccinated young adults since 2004, the study noted. In April, an outbreak of mumps was reported at Temple University in Philadelphia. In 2017, health officials responded to an outbreak of mumps in the Denver area.

Such outbreaks suggest a waning of vaccine-induced immunity. Possible factors include a more rapid decline in antibody levels related to the mumps component of the MMR than other components, and a possible mismatch in vaccine strain and outbreak strain. A third dose of the vaccine may be a safe and effective response.

“Physicians are recommended to follow the childhood vaccination program for 2 MMR vaccinations as advised by national health authorities,” Kaaijk told Contagion^®. “Our data strengthen the recent recommendation of the Advisory Committee on Immunization Practices to offer a third dose of a mumps virus-containing vaccine to persons who are identified to be at risk of mumps during an outbreak to prevent mumps virus infection and related complications. In addition, we now provide evidence that MMR-3 vaccination may boost the waning immunity and thereby prevent mumps virus infection and related complications for at least one year.”

The study included 147 participants aged 18 to 25, who had previously received 2 doses of the MMR vaccine. Mumps-specific antibody levels increased from 186 RU/ml (IgG), 89 (JL/ND₅₀), 65 (G/ND₅₀) at baseline to 306, 119, and 88, respectively, at 4 weeks after immunization. At 1 year, levels were 255, 102, 88 respectively.

No serious adverse events were reported during the study. Local adverse events, such as pain, redness, and swelling at the injection site, were reported by 17% of participants. Mild systemic adverse events, including swelling of neck glands, joint or muscle pain, and fever, were reported by 33% of participants.

“We will investigate whether the elevated antibody levels still persist 3 years after the third MMR dose,” Kaaijk told Contagion^®. “In addition to antibodies, other immune factors can play a role in the defense against mumps. We intend to investigate the effects of a third dose of the MMR-vaccine on these other immune factors (‘cellular immunity’) as well.”