Does ACIP recommend immunization of health care workers?
ACIP recommends that all health care workers ensure that they are immune to
varicella, since nosocomial transmission of varicella is well-recognized.
Varicella immunization is
particularly recommended for susceptible health care workers who have close
contact with persons at high risk for serious complications, including a)
premature infants born to susceptible mothers, b) infants who are born at <
28 weeks of gestation or who weigh < 1,000 g at birth (regardless of maternal
immune status), c) pregnant women and d) immunocompromised persons.
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Should health care workers be tested for VZV immunity prior to vaccination?
Data available to date indicate that in the health care setting, a positive
history of disease is a reliable predictor of positive immune status. Among
tested health care workers > 97-99% of those with a positive history had
antibodies when tested. Employees who do not have a convincing history of prior
varicella should be considered susceptible and serological testing can be
offered to determine immune status. Serologic screening of adults with a
negative or uncertain history is cost-saving compared with vaccinating all those
without a definite history, because 70% to 90% are actually immune when tested.
Health care workers from tropical climates are more likely to be susceptible to
varicella as adults than persons born in the U.S. For ensuring that Health care
workers assigned to high risk patients are immune, hospitals may elect to do
serology testing for all such employees irrespective of disease history.
health care workers be tested after vaccination to ensure that they
The ACIP does not recommend routine testing for varicella immunity after two
doses of vaccine because 99% of adults seroconvert after two doses of vaccine.
Additionally, there are difficulties interpreting negative lab tests
post-vaccination since commercially available tests may not be sensitive enough
to detect low levels of antibody post-vaccination. For institutions that choose
to do post-vaccination testing, it is suggested that if EIA tests are used for
initial screening post-vaccination, then further tests should be conducted on
those with negative results using a more sensitive test (e.g.FAMA (flourescent
antibody-to-membrane antigen), latex agglutination).
- How should vaccinated health care workers be managed after exposure to
Hospitals should develop guidelines for management of vaccinated health care
workers who are exposed to varicella. Seroconversion after varicella vaccination
does not always result in full protection against disease. Therefore, the
following measures should be considered for health care workers who are exposed
to natural varicella: a) serological testing for varicella antibody immediately
after VZV exposure; b) retesting 5-6 days later to determine if an anamnestic
response is present; and c) possible furlough or re-assignment of personnel who
do not have detectable antibody.
Should health care workers be furloughed if they develop a rash after
ACIP suggests that hospitals develop their own policies for managing rash
post-vaccination. Uncontrolled trials suggest that approximately 3% of adults
develop a varicella-like rash (with a median of 2 lesions) at the injection
site, and approximately 5.5% develop a generalized rash (median 5 lesions) 2-6
weeks following the first dose of vaccine. The risk of any rash is much lower
after the second dose (<1%). The rash may be atypical for varicella with
macules or papules rather than vesicles. Health care workers who develop a rash
should be evaluated by the occupational health service at the hospital or
medical facility where they work and managed according to hospital policy.
What policies have hospitals developed for managing post-vaccination rash in
Two large university hospitals (Columbia Presbyterian Medical Center in New
York City and Stanford University Hospital in Palo Alto) have instituted the
following policy: a) Employees are instructed that they may develop a rash 2-6
weeks after vaccination and that this rash may be either a localized rash at the
site of vaccination or a diffuse varicella-like rash. Either rash may be
atypical with macules or papules rather than vesicles. Employees are instructed
to report immediately to the occupational health office if a rash develops. b)
Employees with either an injection site rash or a generalized rash are
furloughed until the rash resolves (usually in 2-3 days). The occupational
health office verifies that the rash has resolved and they are not potentially
infectious to others before allowing the employee to resume patient care duties.