Title: Lower Long-term Immunogenicity of Mumps Component After MMR Vaccine
Abstract: Reply: Thank you for the opportunity to reply to the letter from Dr. De Laval and colleagues. We agree with the authors that the mumps vaccine component of measles, mumps, and rubella (MMR) vaccines, and monovalent mumps vaccines, have lower vaccine effectiveness than measles and rubella components or separate measles and rubella vaccines. In the United States, 2 doses of MMR vaccine have been routinely recommended for children since 1989.1 Throughout the world, a number of mumps vaccines strains have been used in mumps/MMR vaccines.2 In the United States, the only strain used in mumps-containing vaccines, including MMR, is the Jeryl Lynn strain, from which the RIT 4385 mumps vaccine strain used in MMR vaccines in France was also derived. The safety and efficacy of the RIT 4385-containing vaccine appear to be similar to other vaccines containing the Jeryl Lynn strain.3 Field measures of vaccine effectiveness are more pertinent than laboratory measures of antibody concentration as a measure of protection against mumps as the correlates of immunity to mumps are poorly understood. The effectiveness of 1 dose of currently available mumps vaccines has been estimated to range from 62% to 91%, whereas for 2 doses, it is approximately 79% to 95%.2,3 Two-dose vaccine effectiveness for the measles and rubella vaccines administered after 12 months of age have been estimated to be >95% for both measles and rubella.4–8 Despite lower effectiveness of the mumps component, inclusion of mumps vaccine in the routine childhood schedule has resulted in an excellent mumps control. Even considering occasional sizeable mumps outbreaks in highly vaccinated populations, throughout the 2000s, there had been ≥96% reduction of number of reported mumps cases in the United States.9,10 Maintaining high 2-dose coverage for MMR vaccine remains an important strategy for the control of mumps.11 Tai-Ho Chen, MD Epidemic Intelligence Service Centers for Disease Control and Prevention Pennsylvania Department of Health Harrisburg, PA Preeta K. Kutty, MD, MPH Jane F. Seward, MB BS, MPH Division of Viral Diseases Centers for Disease Control and Prevention Atlanta, GA