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Source: http://www.thewhig.com/ArticleDisplay.aspx?e=1025719
Will measles make a comeback?; Decreased sporadic exposure may leave adults vulnerable to childhood diseases: experts
Posted By Helen Branswell
Posted -39 sec ago
We call them the diseases of childhood - measles, mumps, rubella and chickenpox, to name a few.
But now that these diseases seldom circulate in countries that immunize against them and immune protection is rarely being naturally refreshed or "boosted" by sporadic exposure, is there a risk that in the future, older adults may find themselves unexpectedly vulnerable to these disease pests from their past?
As we head into a world where an ever-growing - and aging - proportion of the population only has vaccine-acquired protection, what is really known about how long immunity is likely to endure? For that matter, can science be sure that immunity generated by infection - thought for some of these diseases to be lifelong - will endure into old age in the era of vaccines?
"I don't think we know much at all," acknowledges Dr. Samuel Katz, co-inventor of the measles vaccine and a pediatric infectious disease expert at Duke University in Durham, N.C.
Figuring out answers about the durability of immunity - natural and vaccine-acquired - in a time without natural boosting won't be easy. But the last generation to have routinely suffered through most of these diseases is crossing through mid-life and the first generation to have avoided them is hovering around 40.
As both groups head toward the golden years when any waning of their disease defences may be exacerbated by the age-related decline of the immune system, gauging the levels of society's immunity could become key to keeping these nasty invaders out of our communities, experts say.
Dr. Michael Osterholm says scientists should be doing long-term immunity studies - following groups of people for decades - in the way cancer researchers track groups of people to try to discern what causes cancer.
"That would help us understand at what point does the level of protection drop for a population - not any one individual, but a population norm where you would now recommend that a booster shot should occur as a standard of medical practice," suggests Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota.
Before vaccination became commonplace, adults often came in contact with youngsters suffering from mumps, measles and the other childhood diseases. That remained the case in the early days of vaccine administration when these diseases still commonly circulated.
If people had protection - natural or vaccine-acquired - those exposures were actually helpful. They acted as a sort of natural booster shot, reminding the immune system to be on guard for this threat.
Some experts now wonder whether these unrecorded natural boosts may have led medicine to overestimate the durability of immunity generated by childhood vaccinations and maybe even natural infection, though it is thought to be more enduring than vaccine-acquired infection.
Will measles make a comeback?; Decreased sporadic exposure may leave adults vulnerable to childhood diseases: experts
Posted By Helen Branswell
Posted -39 sec ago
We call them the diseases of childhood - measles, mumps, rubella and chickenpox, to name a few.
But now that these diseases seldom circulate in countries that immunize against them and immune protection is rarely being naturally refreshed or "boosted" by sporadic exposure, is there a risk that in the future, older adults may find themselves unexpectedly vulnerable to these disease pests from their past?
As we head into a world where an ever-growing - and aging - proportion of the population only has vaccine-acquired protection, what is really known about how long immunity is likely to endure? For that matter, can science be sure that immunity generated by infection - thought for some of these diseases to be lifelong - will endure into old age in the era of vaccines?
"I don't think we know much at all," acknowledges Dr. Samuel Katz, co-inventor of the measles vaccine and a pediatric infectious disease expert at Duke University in Durham, N.C.
Figuring out answers about the durability of immunity - natural and vaccine-acquired - in a time without natural boosting won't be easy. But the last generation to have routinely suffered through most of these diseases is crossing through mid-life and the first generation to have avoided them is hovering around 40.
As both groups head toward the golden years when any waning of their disease defences may be exacerbated by the age-related decline of the immune system, gauging the levels of society's immunity could become key to keeping these nasty invaders out of our communities, experts say.
Dr. Michael Osterholm says scientists should be doing long-term immunity studies - following groups of people for decades - in the way cancer researchers track groups of people to try to discern what causes cancer.
"That would help us understand at what point does the level of protection drop for a population - not any one individual, but a population norm where you would now recommend that a booster shot should occur as a standard of medical practice," suggests Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota.
Before vaccination became commonplace, adults often came in contact with youngsters suffering from mumps, measles and the other childhood diseases. That remained the case in the early days of vaccine administration when these diseases still commonly circulated.
If people had protection - natural or vaccine-acquired - those exposures were actually helpful. They acted as a sort of natural booster shot, reminding the immune system to be on guard for this threat.
Some experts now wonder whether these unrecorded natural boosts may have led medicine to overestimate the durability of immunity generated by childhood vaccinations and maybe even natural infection, though it is thought to be more enduring than vaccine-acquired infection.