Chickenpox Cases Decline
A News & Events entry posted on September 4, 2008
Cases of chickenpox, a childhood infection that was once nearly universal. Have fallen 57% to 90% in communities across the United States since a vaccine was introduced in 1995, a new report shows.
Before the vaccine, 4 million Americans a year came down with chickenpox, nearly 11,000 were hospitalized and more than 140 died, according to a report from the Centers for Disease Control and Prevention in today’s Pediatrics, the official journal of the American Acadmey of Pediatrics.
Vaccines have reduced infections in every age group, including among babies less than 1 year old, who are too young to be vaccinated, says study author Jane Seward of the CDC’s National Center for Immunizations and Respiratory Diseases. These babies are being protected by "herd immunity," which results when vaccines reduce the opportunities for infection in a community. Deaths in children ages 1 to 9 have declined about 90%, the study shows. Hospitalizations and costs have fallen 75% to 88%. While the vaccine prevents 85% of general infections, it prevents 95% of severe infections, which can lead to pneumonia and a dangerous brain inflammation called encephalitis.
The CDC has revised its recommendations as experts have learned more about the vaccine. The CDC initially recommended one shot for toddler’s ages 12 to 15 months. But a single shot prevents only 85% of infections, Seward says, allowing the virus to break out even in schools where nearly all the children were vaccinated. Chickenpox can spread through direct contact or through the air, as lesions burst open and spew viruses into the air, Seward states.
In 2006, the CDC suggested a booster shot for children ages 4 to 6. About 89% of children ages 19 to 35 months had received the shot by 2006. Even with two shots, vaccination still saves money, given the expenses of hospitalization and doctors’ visits the study shows.
Doctors continue to study chickenpox and how the vaccine is changing who gets sick and when and also learning about vaccine safety.
Children who received a single combined vaccine protecting against chickenpox as well as measles, mumps and rubella were twice as likely to develop fever and seizures, compared with those who got the chickenpox shot separately from the measles/mumps/rubella vaccine, the study shows.
About 5% of negative reactions to the vaccine have been serious, causing problems such as pneumonia and hepatitis, the study shows. All of those problems occurred in patients with serious but previously undiagnosed medical conditions.
Because the vaccine is new, doctors don’t yet know how long its protection will last. Doctors are closely studying how the vaccine will affect cases of shingles. That condition occurs when the chickenpox virus, which has been hibernating in the body for years or decades, suddenly re-emerges, causing painful sores. Shingles can affect both those who have had chickenpox as well as those who avoided chickenpox through vaccination. Experts recommend that adults over 60 get a shingles vaccine, because the condition becomes more common later in life.
Before the vaccine was introduced, people might be re-exposed to chickenpox many times throughout their lives. Those who had already had the disease didn’t get sick. But their immune systems got the equivalent of a booster shot from each encounter with the virus. Those boosts probably helped keep the virus in check, preventing shingles.
Information provided by, USA Today: http://www.usatoday.com/news/health/2008-09-01-chickenpox_N.htm?loc=interstitialskip
News & Events by Month
PIV Newsletter
The PIV Newsletter features all News & Events entries as well as additional info.
View the Archive.
Managed by Constant Contact.