CPV Has Cut Incidence In US By 90%

iVillage Member
Registered: 12-14-2005
CPV Has Cut Incidence In US By 90%
3
Thu, 09-04-2008 - 2:05pm

Decade Of Chickenpox Vaccination Has Cut Incidence In US By 90 Per Cent
03 Sep 2008

A study reviewing a decade of chickenpox prevention in the United States found that vaccination has resulted in a dramatic 90 per cent reduction in the disease, but even though the coverage was high, the single dose system did not confer sufficient immunity to stop the disease spreading. Experts are backing the 2-dose system that was introduced in 2006.

The study was the work of researchers from the Centers for Disease Control and Prevention (CDC), in Atlanta, Georgia, and from Tufts University School of Medicine, in Boston, Massachusetts, and was published in the 1st September online issue of the journal Pediatrics.

The US was the first country in 1995 to bring in a single-dose chickenpox (varicella) vaccination program for all children. This policy changed to a two-dose system in 2006, with a top up dose for older children to catch up, because it was believed that the single-dose system would not be enough to prevent the spread of the disease.

The purpose of the study was to review a decade of experience with the single-dose system, and what evidence there might be contrasting the single and double dose method, in order to inform and identify challenges for policy makers.

The CDC and Tufts researchers reviewed the relevant published evidence on "varicella," "varicella vaccine," and "herpes zoster" (commonly known as "shingles") and found that for the period 1995 to 2006:

* The single dose chickenpox vaccine was 80 to 85 per cent effective at preventing the disease, whether mild or severe, and over 95 per cent effective at preventing the severe form.

* The single dose vaccination had an excellent safety profile.

* The single dose vaccination program reduced disease incidence by 90 per cent, hospitalizations by 88 per cent, and deaths by over 74 per cent.

* The effect on costs was equally dramatic, showing a 74 per cent reduction in direct inpatient and outpatient medical expenditures over the period.

* The rapid decline in cases plateaued from 2003 to 2006, and outbreaks still occurred, even among school populations with a high percentage of vaccinations.

* Clinical trial evidence showed that compared with children given the single dose, those who received 2 doses developed higher immunity to the disease (as measured by antibody titers).

* The figures showed the 2 dose children had a 3.3 lower risk of breakthrough disease.

* The evidence for herpes zoster was not so clear cut, with 2 studies showing there was no overall increase in incidence and two studies showing there was.

The authors concluded that:

"A decade of varicella prevention in the United States has resulted in a dramatic decline in disease; however, even with high vaccination coverage, the effectiveness of 1 dose of vaccine did not generate sufficient population immunity to prevent community transmission. "

ABC news reported that experts are concerned that many parents don't take chickenpox seriously enough and there is a lack of awareness of just how many deaths there used to be, around two hundred per year, from the disease.

There is still a culture of the "chickenpox sleepover" among some parents, where news that one child has chickenpox causes them to place their non-infected children in close contact with the infected child so they become infected in a "planned" way.

Mark Slifka, associate scientist at the Vaccine and Gene Therapy Institute at the Oregon Health and Science University, told ABC this was "irresponsible" and parents would do better to get their children vaccinated:

"The vaccine is a vastly weaker strain of the same virus, and therefore much safer and with fewer side effects or disease complications," said Slifka.

Even though they are unlikely to end up in hospital, and the risk of death is very low, what is the point of making your children suffer the discomfort of the full blown illness when the vaccine is safe and only gives them a mild experience of the disease? That is the message the experts are trying to get across to parents now, and close the transmission "gap" for good.

"Varicella Prevention in the United States: A Review of Successes and Challenges."
Marin, Mona, Meissner, H. Cody, Seward, Jane F.
Pediatrics, Vol. 122 No. 3, e744-e751, Published online September 1, 2008.
DOI:10.1542/peds.2008-0567.
http://pediatrics.aappublications.org/cgi/citmgr?gca=pediatrics;122/3/e744

From http://www.medicalnewstoday.com/articles/120188.php






iVillage Member
Registered: 07-17-2005
Sun, 09-14-2008 - 10:43pm

"The US was the first country in 1995 to bring in a single-dose chickenpox (varicella) vaccination program for all children."

Does that mean that every single American ran out and got that vaccine in 1995? How many did get it immediately? And that would leave how many un"protected" from chicken pox? Some states, not all, might offer this new vaccine free to the public immediately. Since it costs money, most people would pass until they made it mandatory to "go to school" (big fat lie). And how many illegal aliens go to public school without vaccination at all I wonder? OK, I'm guessing there were few with the vaccine and a whole lot without.

"* The single dose chickenpox vaccine was 80 to 85 per cent effective at preventing the disease, whether mild or severe, and over 95 per cent effective at preventing the severe form."

Are they saying they followed every single child who got that vaccine and asked 5 or 6 years later whether they got chicken pox or not? So 15 - 20% of kids DID get the pox?

I wonder what they meant by different "forms"? How many forms of chicken pox do we have?

"* The single dose vaccination program reduced disease incidence by 90 per cent, hospitalizations by 88 per cent, and deaths by over 74 per cent."

90 Per cent and they need a second shot? I'm confused - 90 per cent of whom??? And in the previous quote - that 95 per cent effective rate - of who - the general population or in the vaccinated population? Or would that be 10 people in a trial?

Thanks, if anyone can help me understand this I would appreciate it!

iVillage Member
Registered: 07-17-2005
Sun, 09-14-2008 - 10:47pm

"around two hundred per year"

When was that?

iVillage Member
Registered: 07-17-2005
Sun, 09-14-2008 - 10:55pm

"There is still a culture of the "chickenpox sleepover" among some parents, where news that one child has chickenpox causes them to place their non-infected children in close contact with the infected child so they become infected in a "planned" way."

And parents believe that this will work. They want it to work, they want their kids to have life-long immunity. This comes only via natural disease - the vaccine(s) will wane over time. Unfortunately, I have anecdotal evidence that chicken pox parties don't always work. I wish we had all had enough money to get all those kids titres run! But try and tell some people that you can have antibodies without a vaccine and they just cannot wrap their brains around the idea. Proof all around but no, doctors don't tell us this so it must be a lie! (eyeroll)