Is one dose of chickenpox vaccine enough
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NEW YORK (Reuters Health) -- Kids are less likely to get chickenpox if they get two doses of the chickenpox vaccine instead of just one, suggests a new study. Most infected people simply feel miserable -- with symptoms including an itchy, blister-like rash, fever, headache and fatigue -- but some do develop serious complications. While routine vaccination has made a big dent in the number of chickenpox cases in the U.S. over the past 15 years, it
doesn’t offer perfect protection -- either because the vaccine didn’t work the first time, or because its effects can eventually wear off. Seeking to solve that problem, the U.S. Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics (AAP) in 2006 recommended a second dose of the vaccine for kids ages 4 to 6. The first dose is typically given at 12 to 18 months of age. “Despite the reasonably (high) effectiveness of one dose of the vaccine, there were
still outbreaks in schools and daycare centers -- even though there was a pretty good rate of vaccination,” Dr. Eugene Shapiro, the study’s lead author from the Yale University School of Medicine in New Haven, Connecticut, told Reuters Health. In the current study, published in The Journal of Infectious Diseases, Shapiro and his colleagues tested the effectiveness of adding the second dose by comparing kids with chickenpox and kids without chickenpox to see how many doses of the vaccine
both had received. Starting right after the CDC updated its recommendation through the beginning of 2010, Shapiro and colleagues found 71 infected children age 4 and up from local pediatricians’ offices. For each of those kids, the researchers found two others who were the same age and saw pediatricians from the same practice. Then they reviewed their medical records for vaccinations. Of the 71 patients with chickenpox, none had gotten two doses of the vaccine. Sixty-six of
them had received one dose, while five hadn’t been vaccinated at all. Out of the 140 kids who had never had chickenpox, 22 of them had been vaccinated twice, 117 once, and only one had never gotten the vaccine. Based on those findings, the authors calculated that one dose of the vaccine protected 86 percent of kids, while two doses were 98 percent effective. Although the study was relatively small and didn’t directly compare outcomes for kids who had gotten none, one, or two
doses of the vaccine, doctors are still optimistic about the results. “We are now in the second period of (chickenpox) control,” an editorial in the journal notes, “and version 2.0 looks promising indeed.” “For most children, one dose (is) enough,” said Dr. Margaret Fisher, who was on the AAP committee that recommended adding the extra vaccine dose. “But to really stop the breakthrough cases, we need to add that second dose. I’m delighted now that we have a study that shows that it works.” Two of the study’s authors have financial ties to Merck, the company that sells the vaccine. One dose costs about $80. The chickenpox vaccine sometimes causes soreness or swelling, a fever, or a mild rash, and very rarely more serious reactions. According to the CDC, side effects are more common after the first dose of the vaccine than after the second dose. Although kids who get chickenpox after receiving a single dose generally have a milder version of the virus than kids who haven’t been vaccinated, they can still spread chickenpox to others. And, Shapiro said, those kids may also be at a higher risk of getting shingles, a painful rash that is caused by the same virus as chickenpox, later down the road. “The recommendation for a second dose ... certainly carries the direct cost of additional vaccine doses,” Sarah Clark, of the Child Health Evaluation & Research Unit at the University of Michigan, told Reuters Health in an email. “But (the vaccine) may be helpful in reducing some of these other costs that are incurred because of breakthrough cases,” she added. Shapiro said that despite the study’s convincing results, no one can be sure how the effectiveness of the second dose of the vaccine will hold up many years after vaccination. When he and his colleagues completed their research, Shapiro said, “It was only three and a half years since the new recommendation was made. It remains to be seen what will happen over the long term.” Both Shapiro and Fisher said the take-away message from the study was that parents should make sure their children get a second dose of the vaccine, if they haven’t received it already. SOURCE: bit.ly/i82eIL and bit.ly/hygWB4 Journal of Infectious Diseases, online January 5, 2011. for-phone-onlyfor-tablet-portrait-upfor-tablet-landscape-upfor-desktop-upfor-wide-desktop-up The chickenpox vaccine protects against chickenpox infection. Find out about the vaccine and possible side effects.
Note: There is another varicella vaccine called Zostavax®. This is to protect against shingles and is not given to children. What is chickenpox vaccine?Chickenpox vaccine protects against infection from the varicella zoster virus, which causes chickenpox infection. The virus is easily spread by sneezing and coughing, or by contact with weeping chickenpox blisters. You can even catch the chickenpox virus from touching clothing or other objects that have fluid from the blister on them. The chickenpox vaccine is a live vaccine which is made using chickenpox viruses that have been weakened (or attenuated), before being included in the vaccine. After vaccination, the weakened vaccine viruses replicate (grow) inside you. This means a very small dose of virus is given to stimulate a response by your immune system. Live attenuated vaccines don't usually cause disease in vaccinated people who have a healthy immune system. When a live attenuated vaccine does cause any illness, it is usually milder than if you had caught the disease. Live attenuated vaccines given by injection are generally effective after one dose. Why is vaccination against chickenpox important?In most people, chickenpox is a mild disease that doesn't cause any lasting problems. Around 1 in 20 healthy children develop a bacterial skin infection from chickenpox, which needs antibiotic medicine. Untreated bacterial skin infections can lead to bacterial infection in other parts of your body, including pneumonia and blood stream infection (septicaemia). Other complications of chickenpox are rare and include encephalitis (brain inflammation) and inflammation of your joints, kidneys and liver. Chickenpox tends to be more severe in adolescents and adults, pregnant women and their unborn babies and people of any age with poorly functioning immune systems. Read more about chickenpox. Pregnant womenChickenpox during pregnancy can spread to your baby. The highest risk is during the first 20 weeks of pregnancy. Up to 2 in 100 infants exposed to chickenpox before birth are born with congenital varicella syndrome and may have skin scarring, eye, limb and brain abnormalities, developmental delay and a poor outcome. Up to 30 in 100 newborn babies with chickenpox develop severe disease that can result in death. Pregnant women should not be given the chickenpox vaccine. The vaccine’s safety in the unborn baby has not yet been demonstrated, although no harmful effects have been described following inadvertent administration to pregnant women. When you get vaccinated, you should avoid getting pregnant for at least 1 month afterwards. If you're planning a pregnancy, check in early with your midwife or doctor to see whether you need to be vaccinated against chickenpox. Who should be vaccinated against chickenpox?Chickenpox vaccination is recommended and funded in New Zealand for the following groups:
The vaccine is funded for certain high-risk individuals and/or their close contacts, regardless of age. People with a weakened immune system are at high risk, but may not be able to have the vaccination themselves, so it's recommended that close contacts of these people be vaccinated. Discuss this with your GP. Chickenpox vaccination is also recommended, but not funded, for:
Who should NOT be vaccinated against chickenpox?Chickenpox vaccine is a live vaccine. This means that it can cause chickenpox, although it is usually milder, and it should not be used for certain groups of people who have reduced infection-fighting ability (immunity), such as if you:
How effective is the chickenpox vaccine?A single chickenpox vaccine dose provides about 99% protection against severe disease and 80% protection against chickenpox infection of any severity. It is still possible to get chickenpox after having the vaccine, but the infection is usually mild. How is the chickenpox vaccine given?The chickenpox vaccine is given as an intramuscular injection (injected into the muscle either in your thigh or upper arm). It is usually given as 1 dose, but 2 doses may be recommended for some people. What are the side effects of chickenpox vaccine?Like all medicines vaccines can cause side effects, although not everyone gets them.
Where can I get vaccinated?The best place to go for vaccinations is your family medical clinic. They have your medical records and can check to see if you’ve already had a particular vaccination. Either your doctor or a nurse can give the vaccination. Learn moreThe following links have more information on chickenpox vaccines:
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