Only written documentation of receipt of vaccines was accepted as evidence of prior immunization. Conditional logistic regression was used to calculate matched ORs for the effects of time since vaccination and age at the time of vaccination, as well as to adjust for effects of possible confounders, including sex, race, attendance at group day care, asthma, use of steroids, and receipt of varicella vaccine within 28 days after receiving the measles-mumps-rubella MMR vaccine.
Three separate conditional logistic regression models were run: one to assess the effect of time since vaccination a dummy-coded variable , one to assess the effect of age at the time of vaccination also a dummy-coded variable , and one to assess the interaction between age and time since vaccination. All P values are 2-sided. As a strategy to assess whether there might have been bias introduced in the selection of the controls, we compared the proportion of subjects who had received the MMR vaccine among both the cases and the controls.
A significant difference could indicate that selection bias may have been a problem since this may be a marker for use of medical care. We also performed an analysis in which we assessed the vaccine's effectiveness for potential cases whose PCR test results were negative ie, children who did not have chickenpox by our definition.
If, using the same methods, the study showed that the vaccine's effectiveness in preventing PCR-positive varicella was good but the vaccine was not effective in preventing PCR-negative potential cases of varicella, it would be strong evidence that the results were not attributable to bias since all potential cases and controls were selected in the same manner.
Information was complete for the case and at least 1 matched control for matched case-control groups in which the results of the PCR assays in the potential case subjects were positive. Data from these subjects formed the basis for the analyses of the effectiveness of the vaccine.
Characteristics of the subjects included in the analyses of the vaccine's effectiveness are shown in Table 1. Cases and controls were similar in demographic characteristics but differed in receipt of varicella vaccine and in the proportions vaccinated at younger than 15 months and at 12 months or less before the onset of varicella in the case subjects.
The numbers of cases who were enrolled each year who were included in the analyses were 75, 71, 68, 48, 33, 43, and 1, respectively. The results of the unadjusted estimate of the overall effectiveness of the vaccine are shown in Table 2. Of the case-control groups, had 2 matched controls and 9 had 1 matched control.
The effectiveness was virtually unchanged after controlling for potential confounders sex, race, location of care during the day, history of asthma, use of corticosteroids, and receipt of varicella vaccine within 28 days after being immunized with the MMR vaccine. Chickenpox was significantly more severe in unvaccinated children mean [SD] and median [interquartile range] severity scores, 7. The trend for the decrease in the vaccine's effectiveness with time was not linear.
Consequently, we combined the estimates of the vaccine's effectiveness for years 2 through 8 Table 3. The vaccine's effectiveness in year 1 vs years 2 to 8 was also significantly different if the child was 15 months or older at the time of vaccination but not if the child was younger than 15 months at the time of vaccination. Although there was a substantial difference in the proportions of cases and controls who had received varicella vaccine, all but 1 case and 1 control had received the MMR vaccine, initial administration of which is recommended at approximately the same age as for the varicella vaccine Table 1.
There were potential cases for whom the PCR test result was negative and for whom information about the potential case and at least 1 matched control was complete. The matched OR was 1. Both of these analyses suggest that bias did not have a substantial effect on the results of this study. This study indicates that at least through the first 8 years after vaccination, the overall effectiveness of live, attenuated varicella vaccine remains good, although breakthrough varicella is not rare.
Most vaccinated children who develop chickenpox have mild disease, regardless of their age at the time of vaccination or the time since vaccination, at least up to 7 to 8 years after vaccination ie, the vaccine's effectiveness against moderate to severe disease is excellent throughout the period of the study.
However, there is a substantial, statistically significant decrease in the vaccine's overall effectiveness in the second year after vaccination, after which the decrease in the vaccine's effectiveness is not statistically significant, at least through years 7 to 8 after vaccination. We do not know the explanation for this phenomenon, although it is consistent with observations in other studies 4 - 6 that the risk of breakthrough infection increases over time.
Presumably, this is a result of waning immunity in a proportion of immunized children in addition to occasional primary vaccine failure. The vaccine's effectiveness in the first year after vaccination is substantially lower in children who are vaccinated at younger than 15 months. It is not known how long a vaccinated person is protected against varicella.
But, live vaccines in general provide long-lasting immunity. Effectiveness over time of varicella vaccine. Ten year follow-up of healthy children who received one or two injections of varicella vaccine.
Pediatr Infect Dis J. Why is the chickenpox vaccine important? What is chickenpox? Chickenpox is caused by a virus. Symptoms of chickenpox include: A red, itchy skin rash with blisters Fever Feeling tired Not feeling hungry Headache Chickenpox usually spreads when a person touches chickenpox or shingles blisters — or if they breathe in the virus. Who needs to get the chickenpox vaccine?
Children Children age 12 months and older need to get the chickenpox vaccine as part of their routine vaccine schedule. See the routine vaccination schedule for infants and children. Who should not get the chickenpox vaccine? What are the side effects of the chickenpox vaccine? Side effects are usually mild and go away in a few days.
Although most breakthrough disease is very mild, the child is contagious and activities should be restricted to the same extent as an unvaccinated person with varicella disease. Can a young child, who was recently vaccinated for chickenpox, spread the vaccine virus to other household members? Available data suggest that healthy children are unlikely to transmit vaccine virus. Transmission of vaccine virus to a household contact has rarely been documented.
It appears that transmission of vaccine occurs mostly, or perhaps even exclusively, when the vaccinated person develops a rash following vaccination. If a person develops a rash after receiving varicella vaccination, does he need to be isolated from susceptible people who are either pregnant or immunosuppressed? Transmission of varicella vaccine virus is rare. However, if a pregnant or immunosuppressed household contact of a vaccinated person is known to be susceptible to varicella, and if the vaccinee develops a rash 7 to 21 days following vaccination, it is prudent that they avoid prolonged close contact with the susceptible person until the rash resolves.
An 8-month-old was erroneously given varicella vaccine. What might the consequences be? What should we do now? An 8-month-old is likely to have residual passive varicella antibody from his or her mother. The vaccine probably will have no effect, and no action is necessary. The dose should not be counted, and the child should be revaccinated on schedule at 12 through 15 months of age. Varicella zoster immune globulin VariZIG, Saol Therapeutics is a human blood product prepared from plasma obtained from healthy, volunteer blood donors identified by routine screening to have high antibody titers to varicella-zoster virus.
The first varicella zoster immune globulin, VZIG, became available in According to CDC the decision to administer VariZIG depends on three factors: 1 whether the patient lacks evidence of immunity to varicella, 2 whether the exposure is likely to result in infection, and 3 whether the patient is at greater risk for varicella complications than the general population.
For high-risk patients who have additional exposures to varicella-zoster virus 3 weeks or longer after initial VariZIG administration, another dose of VariZIG should be considered.
The most recent recommendations for the use of VariZIG were published in and are available at www. What groups of patients are eligible for VariZIG? VariZIG is recommended for patients without evidence of immunity to varicella who are at high risk for severe varicella and complications, who have been exposed to varicella or herpes zoster, and for whom varicella vaccine is contraindicated. What is the recommended dosage of VariZIG? VariZIG is supplied in IU vials and should be administered intramuscularly as directed by the manufacturer.
The minimum dose is For ordering information see varizig. A one-month-old infant was exposed for the last 6 days to chickenpox. What should be done to protect the exposed infant, who is too young to vaccinate? There is no evidence that healthy full-term infants born to women in whom varicella occurs more than 48 hours after delivery are at increased risk for serious complications such as pneumonia or death.
Varicella zoster immune globulin, VariZIG, can be given up to 10 days after exposure but is only recommended for newborn infants whose mothers have signs and symptoms of varicella around the time of delivery 5 days before to 2 days after , hospitalized premature infants born at 28 or more weeks of gestation whose mothers do not have evidence of immunity to varicella, or hospitalized premature infants born at less than 28 weeks of gestation or who weigh 1, grams or less at birth regardless of their mothers' evidence of immunity to varicella.
Assuming this is an infant at home, VariZIG would not be recommended. Varicella, if it develops, would be managed as for any child. Storage and Handling Back to top How should varicella vaccine be stored in my clinic? These vaccines can deteriorate rapidly after they are removed from the freezer. A stand-alone storage unit that is frost-free or has an automatic defrost cycle is preferred.
Frozen vaccines should not be stored in the freezer compartment of a combination unit because household freezers cannot maintain proper storage temperatures for frozen vaccines. This applies to both temporary and long-term storage of frozen vaccines. The diluents should be kept separately in the refrigerator or at room temperature.
Live varicella-containing vaccines must be administered within 30 minutes of reconstitution. What happens if you put varicella vaccine in the refrigerator instead of the freezer? Vaccine will be damaged if not stored according to the manufacturer's instructions. However, it may still be possible to use vaccine that has not been properly stored. Put the affected vaccine vials into the freezer after you have marked them so they are not confused with the unaffected vials, then call the manufacturer at VARIVAX for further guidance about whether the vaccine is still usable.
Unreconstituted varicella vaccine may be stored in the refrigerator for up to 72 hours before use. If refrigerated varicella vaccine is not used within 72 hours, it should be discarded. If you have inadvertently left your vaccine at room temperature instead of in the freezer or have experienced a power failure, label the affected vaccine to keep it separated from unaffected vaccine and return it to recommended storage conditions in a freezer promptly, then contact the manufacturer for further guidance.
Do not administer the vaccine until you have consulted with Merck. How can I transport varicella vaccine? What if I do not have access to a portable freezer? The vaccine manufacturer does not recommend transporting varicella-containing vaccines varicella, MMRV. Do not use dry ice, even for temporary storage. Any stand-alone freezer that maintains these temperatures is acceptable. I was told by a coworker that varicella vaccine can be stored at refrigerator temperature for up to three days and still be used.
Is this true? Back to top This page was updated on February 19, This page was reviewed on September 5, Immunization Action Coalition. Sign up for email newsletter.
ACIP Recommendations. Package Inserts. Additional Immunization Resources. Adult Vaccination. Screening Checklists. Ask the Experts. Shop IAC. CDC Schedules. Standing Orders for Vaccination. Clinic Tools. State Laws and Mandates.
Handouts for Patients and Staff. Technically Speaking. Honor Rolls for Patient Safety. Unprotected People Stories. IAC Express. Vaccine Information Statements. View All Materials. Pregnancy and Vaccines.
Top Handouts. Topic Index. Vaccine Index. Schedules for Patients. Language Index. Administering Vaccines. Standing Orders Templates. Adolescent Vaccination. Storage and Handling.
Strategies and Policies. Temperature Logs. Documenting Vaccination. Vaccine Confidence. Healthcare Personnel. Vaccine Recommendations. Managing Vaccine Reactions. Promotional Materials. Parent Handouts. What's New: Handouts. Related Tools:. Documenting Vaccinations. IAC Express - Subscribe.
Scheduling Vaccines. Image Library. Screening for Contraindications. Vaccinating Adults Guide. Translations Index.
0コメント