Shiloh
Editor, Senior Moderator
Source: http://www.medscape.com/viewarticle/578828
From Medscape Pediatrics
Mumps Resurgence in the United States
Posted 08/22/2008
William T. Basco, Jr., MD, FAAP
Recent Resurgence of Mumps in the United States
Dayan GH, Quinlisk P, Parker AA, et al
N Engl J Med. 2008;358:1580-1589
Summary
This study reviewed the epidemiology of recent mumps outbreaks in the United States to better understand the pattern of susceptible individuals. The data were obtained from a CDC surveillance system using data provided by state health departments.
The case definition included acute onset of parotid or other salivary gland swelling and pain that lasted for at least 2 days. These were considered confirmed cases if there was accompanying laboratory evidence and probable cases if not. The authors divided the time period of interest into the "pre-resurgence" period (2000-2005), resurgence period (2006), and post-resurgence (January 2007-June 2007).
The authors used data from 4 different surveys to estimate vaccine coverage for mumps-containing vaccine during the study period. The authors note that from 2000 to 2005, there were fewer than 350 cases of mumps in the United States per year. In 2006, several states experienced outbreaks of mumps, primarily on college campuses.
During all of 2006, there were more than 6500 cases total involving subjects from 45 states. During the post-resurgence period, there were 359 cases, double the pre-resurgence rates but much lower than those recorded in 2006.
The authors note that vaccine coverage among children 13-17 in the United States during 2006 was 87% for 2 doses of mumps-containing vaccine (usually measles-mumps-rubella). In fact, 63% of persons who developed mumps in 2006 had received 2 doses. Only 13% were unvaccinated.
Mumps rates were higher in females and nonminority individuals, and neither of these disparities was explained by differing rates of vaccination. The authors note that the 2006 outbreak suggests a fairly widespread failure of 2-dose coverage of mumps-containing vaccine.
The authors stress that even 87% coverage with 2 doses may not reach the population herd-immunity threshold needed to prevent mumps outbreaks, and waning immunity may also be involved.
The authors concluded that changes in current vaccine schedules or vaccine immunogenicity will be needed to prevent future outbreaks.
Viewpoint
The authors speculate that the high rates of failure of 2-dose coverage may be a big part of the reason why college students seem so susceptible: They do not have natural exposures to provide periodic boosts to their immunity. The authors review data which establish the fact that many of the cases had received the second dose of mumps-containing vaccine 10 years or more before the outbreaks. This concern seems reminiscent of the concerns about whether we will see adult outbreaks of varicella once community levels drop too low to provide periodic boosting. Stay tuned!
From Medscape Pediatrics
Mumps Resurgence in the United States
Posted 08/22/2008
William T. Basco, Jr., MD, FAAP
Recent Resurgence of Mumps in the United States
Dayan GH, Quinlisk P, Parker AA, et al
N Engl J Med. 2008;358:1580-1589
Summary
This study reviewed the epidemiology of recent mumps outbreaks in the United States to better understand the pattern of susceptible individuals. The data were obtained from a CDC surveillance system using data provided by state health departments.
The case definition included acute onset of parotid or other salivary gland swelling and pain that lasted for at least 2 days. These were considered confirmed cases if there was accompanying laboratory evidence and probable cases if not. The authors divided the time period of interest into the "pre-resurgence" period (2000-2005), resurgence period (2006), and post-resurgence (January 2007-June 2007).
The authors used data from 4 different surveys to estimate vaccine coverage for mumps-containing vaccine during the study period. The authors note that from 2000 to 2005, there were fewer than 350 cases of mumps in the United States per year. In 2006, several states experienced outbreaks of mumps, primarily on college campuses.
During all of 2006, there were more than 6500 cases total involving subjects from 45 states. During the post-resurgence period, there were 359 cases, double the pre-resurgence rates but much lower than those recorded in 2006.
The authors note that vaccine coverage among children 13-17 in the United States during 2006 was 87% for 2 doses of mumps-containing vaccine (usually measles-mumps-rubella). In fact, 63% of persons who developed mumps in 2006 had received 2 doses. Only 13% were unvaccinated.
Mumps rates were higher in females and nonminority individuals, and neither of these disparities was explained by differing rates of vaccination. The authors note that the 2006 outbreak suggests a fairly widespread failure of 2-dose coverage of mumps-containing vaccine.
The authors stress that even 87% coverage with 2 doses may not reach the population herd-immunity threshold needed to prevent mumps outbreaks, and waning immunity may also be involved.
The authors concluded that changes in current vaccine schedules or vaccine immunogenicity will be needed to prevent future outbreaks.
Viewpoint
The authors speculate that the high rates of failure of 2-dose coverage may be a big part of the reason why college students seem so susceptible: They do not have natural exposures to provide periodic boosts to their immunity. The authors review data which establish the fact that many of the cases had received the second dose of mumps-containing vaccine 10 years or more before the outbreaks. This concern seems reminiscent of the concerns about whether we will see adult outbreaks of varicella once community levels drop too low to provide periodic boosting. Stay tuned!