|
|
|
|
|
| How serious a
disease is varicella? |
 |
| Prior to the
availability of varicella vaccine there were approximately 4 million
cases of varicella a year in the U.S.
Though usually a mild disease in healthy children, an estimated 150,000
to 200,000 people developed complications, about
10,000 people required hospitalization and 100 people died each year
from varicella. Varicella tends to be more severe in
adolescents and adults than in young children. The most common
complications from varicella include bacterial superinfection
of skin lesions, pneumonia, central nervous system involvement, and
thrombocytopenia. |
| |
| How is
varicella transmitted and for how long is an infected person contagious? |
|
| Chickenpox spreads from person to person
by direct contact or through the air by coughing or sneezing. It is
highly
contagious. It can also be spread through direct contact with fluid from
a blister of a person infected with chickenpox, or
from direct contact with a sore from a person with shingles. People with
chickenpox are infectious for at least 6-7 days
after the appearance of spots and until all lesions are crusted over. |
|
| How are
we doing as a nation in vaccinating children and adolescents against
varicella? |
|
| From 1997 to mid-2009, vaccination with
1 dose of varicella vaccine increased from 26% to 93% among 19-35 month
old children, according to the National Immunization Survey (NIS). In
addition, NIS data in 2009 for adolescents 13–17 years showed 87% had
one or more doses of varicella vaccine. As of September 2010,
vaccination requirements for one dose of varicella vaccine exist in all
but one state (Idaho) and, evidence of two doses is required in more
than half of the states for either for children in child care settings,
schools, or both. These are all remarkable achievements during the short
period of time following the licensure of the vaccine in 1995. |
|
| Do all states have varicella
vaccination requirements before school entry? |
|
| No. To find out which states have laws
regarding varicella vaccine requirements, go to IAC's website at www.immunize.org/laws. In 2005, CDC recommended expanding the
requirements to cover students in all grade levels. Government health
agencies at the state level should take necessary steps, including
developing and enforcing school immunization requirements, to ensure
that students at all grade levels (including college) and children in
child care centers are protected against varicella and other
vaccine-preventable diseases. |
|
| How has widespread use of varicella
vaccine in children impacted disease? |
|
| Substantial reductions in varicella
morbidity and mortality have occurred following the licensure of
vaccine. Information from three active varicella surveillance areas
reported varicella cases had declined by 83%--93% by 2004, and varicella
hospitalizations and deaths declined by more than 90%. |
|
What can be done to protect a patient
without evidence of immunity who is exposed to varicella and is at high
risk for severe
disease and complications? |
|
| These patients should receive varicella
zoster immune globulin (VZIG). If given within 96 hours of exposure,
VZIG can modify or prevent clinical varicella disease. In 2006, an
investigational VZIG product, VariZIG, became available to requestors
from the sole authorized U.S. distributor, FFF Enterprises. Details on
the use of VZIG may be found in the 1996 varicella ACIP statement (MMWR
1996; 45 [RR-11]:20-24), and details on the use of VariZIG can be found
in the MMWR (MMWR 2006; 55[08]:209-210) found at www.cdc.gov/nip/publications/ACIP-list.htm |
|
|
|
|
|
| Who is recommended to be vaccinated
against varicella? |
|
| All children, beginning at age 12
months, as well as adults without other evidence of immunity (see next
question) should be vaccinated with 2 doses of varicella vaccine.
Special consideration should be given to vaccinating adults who (1) have
close contact with people at high risk for severe disease (e.g.,
healthcare workers and family contacts of immunocompromised people), or
(2) are at high risk for exposure or transmission (e.g., teachers of
young children; child care employees; residents and staff members of
institutional settings, including correctional institutions; college
students; military personnel; adolescents and adults living in
households with children; non-pregnant women of childbearing age; and
international travelers). |
|
| What are the criteria for evidence of
immunity to varicella? |
|
| ACIP considers evidence of
immunity to varicella to be |
|
| • |
|
Documentation of 2 doses
of vaccine given no earlier than age 12 months, with at least 3
months between doses for children younger than age 13 years, or at
least 4 weeks between doses for people age 13 years and older |
| • |
|
U.S.-born before 1980* |
| • |
|
A healthcare provider's diagnosis of
varicella or verification of history of varicella disease |
| • |
|
History of herpes zoster, based on
healthcare provider diagnosis |
| • |
|
Laboratory evidence of immunity or
laboratory confirmation of disease |
| |
|
*Note: year of birth is not
considered as evidence of immunity for healthcare personnel,
immunosuppressed people, and pregnant women. |
|
|
| Please review the recommendations for
routine second doses of vaccine for everyone, including children. |
|
| In June 2006, ACIP voted to recommend
that all children be given 2 doses of varicella vaccine routinely. The
first dose should be given at age 12-15 months and the second dose at
age 4-6 years. ACIP also recommended "catch-up" vaccination with a
second dose for all adolescents and adults who may have missed a second
dose. For children ages 12 months through 12 years, the minimum interval
between doses is 3 months; for people age 13 years and older, the
minimum interval is 4 weeks. |
|
| Concerning the recommendation for a
second dose of varicella vaccine, does CDC recommend that children who
received 1 varicella vaccine dose 10 years ago (when they were preschool
age) get a second dose now? |
|
| Yes. The current recommendation is for 2
doses regardless of age, for anyone school age and older without
evidence of immunity. For everyone whose varicella immunity is based on
vaccination, 2 doses of varicella vaccine are recommended. |
|
| Why did ACIP revise its
recommendations to add a second dose of varicella vaccine for all
children? |
|
| In the ten years following vaccine
licensure in 1995, there was a significant decline in varicella disease,
as well as varicella-related hospitalizations and deaths. Although a
1-dose regimen was estimated to be 80%-85% effective, breakthrough
disease was still occurring in highly vaccinated populations. A 2-dose
regimen was adopted in 2006 to further reduce the risk of disease among
vaccinated people whose numbers would accumulate over time, which could
lead to varicella disease later in life when it can be more severe. |
|
| Should a child who has had chickenpox
prior to the first birthday get the first dose of varicella vaccine at
age 1 year? |
|
| If the child had confirmed varicella
disease or laboratory evidence of prior disease, it is not necessary to
vaccinate regardless of age at infection. If there is any doubt that the
illness was actually varicella, the child should be vaccinated. |
|
| How important is it to vaccinate
older children and adults? |
|
| It is critical to vaccinate susceptible
older children and adults whenever the opportunity arises. With younger
children being routinely vaccinated, the chance of being exposed to
cases of chickenpox is decreasing. Older children, adolescents, and
adults who have not had chickenpox now have a greater chance of
remaining susceptible. These older individuals, when they contract
chickenpox, are more likely to become seriously ill and have disease
complications than younger children. |
|
| If an adult or child has not had
documented chickenpox but has had shingles, is varicella vaccination
recommended? |
|
| No. Shingles is caused by varicella
zoster, the same virus that causes chickenpox. A history of shingles
based on a healthcare provider diagnosis is evidence of immunity to
chickenpox. Therefore, a person who has had shingles does not need to be
vaccinated against varicella. He/she should still receive zoster
vaccine, however, if it is not contraindicated and he/she is age 60 or
older. |
|
| How safe is varicella vaccine? |
|
| Varicella vaccine is very safe. About
20% of vaccine recipients will have minor injection site complaints,
such as pain, swelling, or redness. Less than 5% of recipients develop a
localized or generalized varicella-like rash 5-26 days after
vaccination. These rashes have an average of 2-5 lesions, and may be
maculopapular rather than vesicular. Fever following varicella vaccine
is uncommon. |
|
| If a child has a very mild case of
chickenpox (e.g., only 5-10 pox), is s/he immune or should s/he be
vaccinated? |
|
| A mild case of chickenpox produces
immunity to varicella as does a moderate or severe case. A child with a
reliable history of chickenpox does not need to receive varicella
vaccine. However, if there is any doubt that the mild illness really was
chickenpox, it is best to vaccinate the child. There is no harm in
vaccinating a child who is already immune. |
|
| If a child had 1 varicella
vaccination and developed a vesicular (chickenpox-like) rash at the
vaccination site 7 to 10 days after vaccination, does the patient still
need the second dose? What if the rash covered the entire body? |
|
| If you believe the child had varicella
disease (that is, breakthrough varicella) after the first dose, the
child does not need another dose. If you are uncertain whether the child
had varicella, the second dose should be administered on schedule. If in
doubt, plan to give the second dose. If this was a case of breakthrough
varicella, a second dose will not be harmful.
|
|
| If a child breaks out in 5-10
maculopapular spots 2 weeks following varicella vaccination, can s/he go
to school? |
|
| Transmission of varicella vaccine virus
is a rare event, and appears to occur only when the vaccinated person
develops a vesicular rash. A maculopapular rash 2 weeks after varicella
vaccine may not have been caused by the vaccine. If the rash were caused
by the vaccine, the risk of transmission is very small; however, the
child should avoid close contact with people who do not have evidence of
varicella immunity and who are at high risk of complications of
varicella, such as immunocompromised people, until the rash has
resolved. |
|
| If a vaccinated child gets 5-10
vesicular lesions 2 weeks after vaccination, can s/he attend school? |
|
| You cannot distinguish a mild case of
varicella disease from a rash caused by the vaccine. The child may have
been infected with varicella at about the same time s/he was vaccinated.
The conservative approach would be to treat the child as if s/he had
chickenpox and restrict her/his activities until all the lesions crust
over. |
|
| If a child gets breakthrough
varicella infection, ~50 lesions, can s/he go to school? |
|
| Breakthrough varicella represents
replication of wild varicella virus in a vaccinated person. 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. |
|
I understand that varicella vaccine
can be used in postexposure settings. How soon after exposure does the
vaccine need to be
given? |
|
| Varicella vaccine is effective in
preventing chickenpox or reducing the severity of the disease if used
within 72 hours (3 days), and possibly up to 5 days, after exposure.
However, not every exposure to varicella leads to infection, so for
future immunity, varicella vaccine should be given, even if more than 5
days have passed since an exposure. |
|
| 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 at 12-15
months of age. |
|
| Does varicella vaccine affect
tuberculosis skin test readings in the same way that MMR does? |
|
| There is currently no information on the
effect of varicella vaccine on reactivity to a tuberculin skin test (TST).
Until information is available, it is prudent to apply the same rules to
varicella vaccine as are applied to MMR: a TST (i.e., PPD) may be
applied before (preferably) or simultaneously with varicella vaccine. If
vaccine has been given, delay the TST for at least 4 weeks. |
|
|
|
|
|
| What is the recommended schedule for
vaccinating a child? What about adults? |
|
| For infants, the first dose should be
given at age 12 months with a second dose given at age 4-6 years.
The second dose could be given earlier, if necessary, as long as
there is a 3-month interval between doses. All other children age
13 years and older as well as adults without evidence of immunity
should also have documentation of 2 doses of varicella vaccine, separated
by a minimum interval of 4 weeks. |
|
| Many children in my practice have had
only 1 dose of varicella vaccine. Is there a problem waiting until the
11- to 12-year-old visit to give them the second dose? |
|
| Don't delay giving the second dose of
varicella vaccine. Give the second dose the next time the child or teen
is in your office. The recommendation to routinely give a second dose at
age 4-6 years is intended to provide improved protection in the 15-20%
of children who do not adequately respond to the first dose. |
|
| What should we do if a child younger
than age 13 years was given a second dose with only a 4
week interval? |
|
| ACIP recommends that if the interval
was at least 28 days it doesn't need to be repeated. |
|
| Under what circumstances should I
obtain a varicella titer after vaccination? |
|
| Postvaccination serologic testing is
not recommended in any group, including
healthcare workers. |
|
| Which of my patients should have varicella
serology prior to receiving varicella vaccine? |
|
| ACIP does not recommend serologic
testing for people younger than age 13 years. At least 90% of
adolescents and adults from the U.S. can be expected to be immune to
varicella, including those who do not recall having had the disease. As
a result, serologic screening may be considered for people age 13 years
and older who do not have a history of chickenpox, a strategy that may
be cost effective, depending on the cost of the serologic test. However,
it is safe to give varicella to people already immune to the disease, so
screening is not required under any circumstance. |
|
| Should I test women for varicella
immunity at their first prenatal visit? |
|
| Test pregnant women who lack either (1)
documentation of receipt of 2 doses of varicella vaccine or (2)
healthcare-provider diagnosis or verification of varicella or herpes
zoster disease. Women who are not immune should begin the 2-dose
vaccination series immediately postpartum. |
|
| What is the appropriate lab test to
use to determine whether there has been previous
chickenpox disease? |
|
| Commercially available laboratory tests
for varicella antibody are usually based on a technique called EIA
(enzyme immunoassay). Though these tests
are sufficiently
sensitive to detect antibody resulting from varicella zoster virus infection,
they are generally not sensitive enough to detect vaccine-induced antibody. The
more sensitive assays needed to detect vaccine-induced antibody are not widely
available. This is why CDC does not recommend antibody testing after varicella
vaccination. |
|
|
|
|
|
| What are the recommendations for the
use of varicella vaccine in children with HIV or other
immunodeficiencies? |
|
| ACIP recommends varicella vaccination of
children with humoral (but not cellular) immunodeficiencies. In
addition, vaccination should be considered for children with HIV
infection in CDC class N, A, or B who have CD4+ T-lymphocyte percentages
of 15% or higher. For additional details of these recommendations, click
here. |
|
| 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 7-21 days following vaccination, it is prudent
that they avoid prolonged close contact with the susceptible person
until the rash resolves. |
|
| After receiving varicella vaccine,
should healthcare personnel avoid contact with immunocompromised
patients? |
|
| No. This is not necessary unless the
person who was vaccinated develops a rash. |
|
| Is there any concern when giving
varicella vaccine to a child who lives with a susceptible pregnant woman
or an immunocompromised individual? |
|
| ACIP recommends varicella vaccine for
healthy household contacts of pregnant women and immunosuppressed
people. Although there may be a small risk of transmission of varicella
vaccine virus to household contacts, the risk is much greater that the
susceptible child will be infected with wild-type varicella, which could
present a more serious threat to household contacts. |
|
| If a patient is breast-feeding her
six-month old baby, can she receive varicella vaccine without the risk
of transmitting the vaccine virus to her baby? |
|
| Yes. There have been no reports of
mother to child transmission of varicella vaccine virus. However,
transmission of vaccine virus to household contacts has been documented
so transmission to a breast-fed infant from its vaccinated mother is at
least theoretically possible. If the susceptible mother were to be
infected with wild varicella virus, the risk of transmission to the
infant would be much higher. So, if the mother is at high risk of
exposure to varicella, the benefits of vaccination probably outweigh the
risk of transmission to the infant. |
|
|
|
|
|
| What are the recommendations for
varicella vaccination before and after pregnancy? |
|
| Live varicella vaccine should not be
given to a woman who is known to be pregnant or who plans to become
pregnant within one month. If a woman who is planning to become pregnant
in the future comes in for a visit or an annual exam, her varicella
history should be obtained and if indicated, 2 doses of vaccine should
be given, spaced 4-8 weeks apart. Pregnant women should be assessed for
evidence of varicella immunity and if non-immune, should receive the
first dose of varicella vaccine following termination or completion of
the pregnancy and prior to hospital discharge. A second dose should be
given 4–8 weeks later. |
|
| Can a pregnant healthcare worker with
a history of varicella infection care for a patient with varicella? Is
it possible for her to have a declining titer, thus making her
susceptible to the virus again? |
|
| People with a reliable history of
varicella can be considered to be immune. A reliable history would
consist of (1) a healthcare provider's diagnosis of varicella or
verification of history of varicella disease; (2) a history of herpes
zoster, based on healthcare provider diagnosis; or (3) laboratory
evidence of immunity or laboratory confirmation of disease. Immunity
following disease or vaccination is probably life-long. More than one
primary infection with varicella is unusual. |
|
| Should all pregnant women have
serology screening for varicella? |
|
| No. Serologic testing for varicella
should be considered only for women who do not have evidence of immunity
(reliable history of chickenpox or documented vaccination). Once a
person has been found to be seropositive, it is not necessary to test
again in the future. |
|
| If a woman receives varicella
vaccine, how long should she wait before becoming pregnant? |
|
| Contrary to the information provided in
the vaccine package insert, which states that pregnancy should be
avoided for 3 months, the ACIP recommends that a wait of 1 month is
sufficient. |
|
| If a woman receives varicella vaccine
and subsequently finds out that she is pregnant, what should she be told
about the risk to the fetus? |
|
| There is no information available
concerning the risk to a fetus if a pregnant woman is inadvertently
given varicella vaccine. However, the risk of congenital varicella
syndrome following varicella disease is small, so the risk of congenital
anomalies following vaccination with live attenuated varicella vaccine
is probably very small. In order to clarify this risk, CDC and Merck
have established a Varicella Vaccination in Pregnancy registry, similar
to that which was established for rubella vaccine inadvertently given
during pregnancy. Healthcare providers are encouraged to report such
incidents by calling the Merck Pregnancy Registry at (800) 986-8999. |
|
|
|
|
|
| How should varicella vaccine be stored
in my clinic? |
|
| Varicella vaccine must be kept frozen
at a temperature of +5°F (-15°C)
or colder until it is reconstituted. Most relatively new frost-free freezers
will maintain this temperature but older dormitory-style refrigerators without
a separate freezer compartment are not adequate. Freezer temperature must be
carefully checked prior to ordering the vaccine. The diluent should be kept separately
in the refrigerator or at room temperature. The vaccine must be administered
within 30 minutes of reconstitution. |
|
| What happens if you put varicella
vaccine in the refrigerator instead of the freezer? |
|
| It's possible that the vaccine could
be damaged if not stored according to the manufacturer's instructions.
However, it may still be possible to use the vaccine.
Put the affected vaccine vials back into the freezer after you have marked them
so that they are not confused with the unaffected vials, then call the Merck
Vaccine Division at 800-9-VARIVAX right away. Merck will make a recommendation
regarding whether the vaccine is still usable, and if so, give you a new expiration
date. Do not administer the vaccine until you have consulted with Merck. Similarly,
if you have inadvertently left your vaccine at room temperature instead of in
the
freezer or have experienced a power failure, the same instructions apply. |
|
| How can I transport varicella vaccine
to a clinic that doesn't have a freezer? |
|
Varicella vaccine is less stable than
other vaccines you routinely handle. Varicella
vaccine must be stored
at 5°F (-15°C) or less in order for the expiration date printed on
the package to be valid. Potency of the vaccine begins to decline within minutes
of being exposed to temperatures above 5°F. Consequently, the vaccine should
be kept at freezer temperature at all times, including during transport between
clinics.
Temperature
can be maintained by transporting the vaccine in the original shipping container
(or a container of comparable insulating quality) with an adequate amount (at
least 6 pounds) of dry ice.
|
If dry ice is not available the vaccine
may be stored at refrigerator temperature 36-46°F (2-8°C)
for up to 72 hours. However, once the vaccine has been removed from
the freezer it should not be refrozen, and must be discarded after
72 hours at refrigerator temperature. Do not, under any circumstances,
use varicella vaccine that has been out of the freezer for more than
72 hours unless it has been kept on dry ice continuously. If you discover
varicella vaccine in the refrigerator, and cannot determine exactly
how long it has been there, the vaccine must be discarded. Never risk
giving your patients varicella vaccine that has been mishandled.
|
If your vaccine supply has been thawed
because of a catastrophic event, such as a power failure, it may still
be potent enough to use. Keep the vaccine cold and estimate the temperature
to which the vaccine was exposed. You must then contact the Merck Vaccine
Division (800-9-VARIVAX) to determine if the vaccine is still usable.
If the vaccine was purchased with state or federal funds, you should
also contact your
state immunization program as soon as possible. |
|
| Reviewed on 9/10 |
A-Z
IAC Home