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PHC 6517: “Varicella: A Case Example of Immunization, PEP & Work

Restriction Challenges”

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• Caused by varicella-zoster virus (VZV)

• Acute viral illness

• 70-90% adults in temperate zones immune (less in tropical areas)

• Incubation period ranges 10-21 days

• Spread by direct contact, aerosols from lesions, or aerosolized respiratory tract secretions

• Hospitalized cases require Contact & AirbornePrecautions

About Varicella

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Varicella (chickenpox)

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Centers for Disease Control1983 & 1998 Guidelines

Category IB Recommendation:

“Non-immune personnel exposedto varicella

should be excluded from workbeginning on the 10th day

after the first exposure until 21 days after the last exposure”

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Category IA & Category IB• Category IA: Strongly recommended for all

hospitals & strongly supported by well-designed experimental or epidemiologic studies

• Category IB: Strongly recommended for all hospitals & reviewed as effective by experts in the field & a consensus of Hospital Infection Control Practices Advisory Committee on the basis of strong rationale & suggestive evidence, even though definitive scientific studies have not been done

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Problems with Implementing CDC Guidelines

• # of employees with directpatient contact

• # of varicella exposures

• Not every exposure results incontracting varicella

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Community Survey:35 Hospitals in

San Francisco Bay Area

• 74% (26) Follow CDC Guidelines:

– 73%(19) Apply to all areas

– 23%(6) Apply to employees with direct patient contact

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8 (23%) Had Alternative Plans

• 4 - Employees work unmasked with daily screening

• 2 - Employees reassigned to non-susceptible areas or home

• 1 - Employees assigned non-patient care areas with immune personnel

• 1 - Employees work masked unless disease develops; no screening

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Employees Sent Home WhoDidn’t Get Varicella

22 (63%)

3- x1

9- x2-4

1- 10-20x

1- 9:1 Ratio

1- Few

1- Numerous

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Santa Clara ValleyMedical Center

3800 Employees:

• 1210 with (-) or (?) varicella history (serological testing done)

• 223 (18%) of history (-), non-immune, or equivocal

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SCVMC Policies

1. All employees tested for VZ upon initial employment or at yearly PPD

2. Verbal history of varicella not accepted

3. Non-immune employees asked to notify Infection Control for home, work or other chickenpox exposures

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SCVMC Policies

4. Allow exposed non-immune employees to work masked unless varicella develops

5. Asked to screen self daily for symptoms

6. If vaccine rash, EH evaluates & sent home if VZ developed

7. If wearing mask, no exposure

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Exposure Data1/85-7/93

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• 134 Varicella Exposure Incidents

• 2,976 employees; 1,235 patients

exposed

• 45 non-immune employees

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Evaluation

• 45 non-immune employees masked post-exposure:

• 4 employees developed varicella–50% Home exposures

–50% Work exposures

• 41 employees did not develop varicella

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Work Days Saved41 non-immune employees

did not develop varicella post-exposure

If restricted from work, would have resulted

in a maximum of lost days

(If they worked all 12 days of incubation period)

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References

• Haiduven DJ, Hench CP, Stevens DA. – Postexposure varicella management of non-immune

personnel: An alternative approach. (1994). Infection Control & Hospital Epidemiology (ICHE), 15: 329-334.

• Haiduven et al:– Postexposure varicella management: further comments.

ICHE 1994 Dec; 15(12): 740-1.

– Postexposure varicella management of nonimmune personnel: an alternative approach. ICHE 1994 May;15(5): 329-34.

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purifying-respirator-apr-also-known-as-a-filtering-facepiece-respirator/attachment/respirator-works-

as-an-air-purifying-respirator-apr-also-known-as-a-filtering-facepiece-respirator

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Questions • What is definition of a

chickenpox exposure?

• Should vaccine be mandated, encouraged, not offered?

• Should there be work restrictions for vaccinated employees post-chickenpox exposure?

• What is (+) history?

• How to manage vaccinated employees exposed to natural varicella?

• Test employees post-vaccination?

• How to handle results of post-vaccination titers?

• Treat positive titers differently in vaccinated vs. unvaccinated employees?

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Definition of Exposure• There were no standardized ones

• How long a contact is needed?

• How do I define it?

• How would you define it?

• Also need herpes zoster exposure definitionSee RR#3 for most current exposure definition

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About the Vaccine

• Live attenuated vaccine

• “Varivax”- Merck

• Safe >2 million in Japan

• 9,454 children & 1,648 adults in U.S. trials

• Licensed in 1995

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CDC Guideline for Infection Controlin Healthcare Personnel, 1998

• Administer vaccine to susceptible personnel, especially those in contact with patients at high risk for serious complications (Cat. IA)

• Do NOT routinely perform post vaccination testing of personnel for antibodies (Cat. IB)

• Develop guidelines for vaccinated personnel:1) exposed to wild-type varicella, 2) who acquire a rash post-vaccine, & 3) who have contact with susceptible persons at high risk for varicella complications (Cat. IB)

See RR#4

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Vaccine PROS

70-90%

protection

against

infection

95% protection against severe disease

for 7-10 years

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Vaccine CONS 10-30% NOT

protected

27% Chance of

breakthrough cases

Vaccine virus

transmission?

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SCVMC Policies

1. All employees tested for VZ

2. Vaccine encouraged- not mandatory

3. Consider vaccinated employees as non-immune

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SCVMC Policies

4. Allow exposed, vaccinated employees to work masked unless varicella develops

5. If vaccine rash, EH evaluates

6. Post-vaccine serologies not done at this time

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1. Is it safe to assume thatstaff will wear masks constantly

when these devices arealmost universally

regarded asuncomfortable & annoying?

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025_Damage_Controlman_1st_Class_Rebecca_Thomas,_from_San_An

tonio,_uses_irritant_smoke_to_test_the_seal_of_a_respirator_durin.jpg

CONCERNS

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Concerns cont’d

2. Will staff change masks every 30-60 minutes or when the mask becomes moist?

2. Will message to employees be-"We no longer take varicella exposures seriously"?

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If masks don’t work, why do we use them for:

• Surgery

• Tuberculosis

• Isolation Cases

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• Work in non-clinical areas with other non-immune employees

• Chart review for clinical staff

• Duties outside clinical areas for non-clinical staff

Alternatives Proposedby Critics

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How to Handle Exposed Vaccinated Employees?

• Consider non-immune

• Ask to notify I.C. if exposed to cp

• Work masked 10-21 days post-exposure

• Screen self daily for symptoms

• Go to E.H. if symptoms develop

• Go home if VZ developshttp://www.cs.odu.edu/~toida/nerzic/390teched/figures/decision-tree-2.jpg

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Algorithms

• #1 Initial & Annual Management of Employees

• #2 Management of Employees Exposed to Varicella

• #3 Management of Post-vaccination Period for Employees

• #4 Management of Pediatric Inpatients

See Accompanying Material

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Ethical Issue with Varicella Vaccine:

Mandate or encourage?

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What is chance of getting herpes zoster if vaccinated?

• VAERS rate of HZ after varicella vaccination was 2.6/100,000 vaccine doses distributed (CDC, 1998, unpublished data). HZ after natural infection among healthy children <20 years 68/100,000 person years &, for all ages, 215/100,000 py.

• A 2008 study HZ incidence, at 1.00 case/1000 person-years.Somewhat lower than previously observed rates of HZ among unvaccinated populations, which ranged from 2.15 -4.05 cases/1000 person-years. Consistent with hypothesis that immunocompetent, vaccinated individuals relatively protected against HZ, compared with unvaccinated persons harboring wild-type VZV. Not known at this time

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Questions

• What is definition of exposure?

• Should vaccine be mandated, encouraged, not offered?

• Should there be work restrictions for vaccinated employees post-chickenpox exposure?

• What is (+) history?

• How to manage vaccinated employees exposed to natural varicella?

• Test employees post-vaccination?

• How to handle results of post-vaccination titers?

• Treat (+) titers differently in vaccinated vs. unvaccinated?

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Definitions

• Varicella Exposure Incidents

• Contagiousness & Masking Period

• Mask

• Non-immune to varicella

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Implications & Necessary Conditions

• Careful evaluation of each exposure

• Daily screening for symptoms

• Education

• Strategies carefully considered & adequately discussed (e.g., committees)

• Policies consistent with existing management of non-immune employees

Consider this approach in appropriate settings

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Reference

Algorithm-based policiesFollow- up data

Haiduven DJ, Hench CP, Simpkins SM, Scott KE & Stevens DA. Infect Control Hosp Epidemiol (ICHE). Management of varicella-vaccinated patients & employees exposed to varicella in the healthcare setting 2003 Jul; 24(7): 538-43.

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Journal Article #1

Wurtz, R. & Check, I. J. (1999). Breakthrough varicella infection in a healthcare worker despite immunity after varicella vaccination. Infection Control & Hospital Epidemiology, 20, 561-562.

• A nurse with one dose of vaccine had local reaction, antibody (+) using IFA

• 9 months later acquired wild-type varicella from son 14 days after his rash

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Journal Article #2Weinstock, D. M., Rogers, M., Lim, S., Eagan, J. & Sepkowitz, K. A. (1999). Serconversion rates in healthcare workers using a latex agglutination assay after varicella virus vaccination. Infection Control & Hospital Epidemiology, 20, 504-507

• Of 57 HCWs who received 2 doses of vaccine, 31 (81.6%) were (+); 7 (18.4%) (-)

• Vaccinated, seronegative employees furloughed day 10-21 post-exposure

• Conclude testing to be used post-vaccination to identify potentially susceptible HCWs

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Journal Article #3• Johnson, C. E., Stancin, T., Fattlar, D., Rome, L.,

& Kumar, M. L. (1997). A long-term prospective study of varicella vaccine in healthy children. Pediatrics, 100, 761-766.

• In 137 seroconverters (97.9%), 25 (18%) acquired varicella

• In 129 seroconverters (93.5%), 22 (17%) acquired varicella

• Used FAMA (fluorescent antibody to membrane antigen)

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What’s New Since This Happened?

• Varicella vaccine PEP in susceptible persons from 3-5 days post-exposure

• Now VariZIG -(immune suppressed, neonates, premature infants, & pregnant women) up to 10 days PEP; then varicella vaccine 5 months later

• 2 doses of varicella vaccine in kids & adults• After 15 million doses, VAERS data report <10 cases of

vaccine virus transmission• Secondary transmission not documented in absence of

vesicular rash post-vaccination• MMRV for children- impacts policies• HZ vaccine for those 60 years & > See S.R. #2

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Future Considerations

• Changing disease epidemiology

• Changing clinical presentation

• Disease recognition challenging & need for laboratory testing

• Higher risk in those emigrating from tropics & subtropics

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Discussion

Extra Credit

Assignment #3