Controlling varicella in the healthcare setting: barriers to varicella vaccination among healthcare workers

Prevention and Control of Nosocomial Varicella During the United States Varicella Vaccination Program Era

The United States varicella vaccination program has successfully reduced varicella incidence and hospitalizations by ≥90%, consequently reducing the risk of nosocomial exposures. However, patients and healthcare personnel (HCP) continue to introduce varicella zoster virus (VZV) into healthcare settings. Herpes zoster (HZ) is less contagious than varicella, but it can also result in exposures. Unrecognized varicella and HZ may lead to extensive contact investigations, control efforts, and HCP furloughs that result in significant disruption of healthcare activities as well as substantial costs. Robust occupational health and infection prevention programs that ensure healthcare personnel immunity and prompt recognition and isolation of patients with varicella or HZ will lower the risk of VZV transmission and reduce or eliminate the need to furlough exposed HCP and associated costs.

Seroprevalence Survey of Varicella, Measles, Rubella, and Hepatitis A and B Viruses in a Multinational Healthcare Workforce in Saudi Arabia

Objective.

To determine the prevalence of the vaccine-preventable diseases caused by varicella, measles, rubella, and hepatitis A and B viruses in a multinational healthcare workforce.

Design.

Prospective cohort study.

Setting.

A 750-bed tertiary care center located in Riyadh, Saudi Arabia.

Methods.

In compliance with hospital policy, newly recruited healthcare workers (HCWs) were enrolled in the study from September 2001 to March 2005. Serum samples were collected from all HCWs during the initial hiring process and tested for IgG antibodies against each of the 5 viral agents. Nonimmune HCWs were subsequently vaccinated at the earliest opportunity.

Results.

A total of 4,006 newly hired (international and local) employees were included in the study. All underwent serologic testing for IgG antibodies against varicella, measles, rubella, hepatitis A, and hepatitis B viruses. Of the total, 63% were female and 37% were male. Middle Eastern employees comprised 47% of the total, followed by employees from the Far East (35%), the West (10%), and Africa (8%). Forty-two percent were nurses, 27% were in administration, 18% were medical technicians, and 13% were physicians. Among the 4,006 newly hired HCWs, 14% had negative IgG antibody test results for varicella virus, 13% for measles virus, 10% for rubella virus, 33% for hepatitis A virus, and 43% for hepatitis B virus. More women than men were susceptible to hepatitis A (40% vs. 24%; P< .001), whereas more men were susceptible to hepatitis B (55% vs. 35%; P< .001). Varicella susceptibility was more common among HCWs from the Far East (19%), whereas susceptibility to measles, rubella, hepatitis A, and hepatitis B was highest among HCWs from the Middle East. Both relative youth and male sex were associated with lack of antibodies against hepatitis B virus and rubella virus. In contrast, female sex and younger age were associated with lack of antibodies against hepatitis A virus (P< .001).

Conclusion.

Seroprevalence surveys of vaccine-preventable diseases among HCWs, although labor intensive, are invaluable in caring for a multinational workforce.

Clinical and economic impact of various strategies for varicella immunity screening and vaccination of health care personnel

BACKGROUND

Exposure to patients with varicella or herpes zoster causes considerable disruption to a health care facility's operations and has a significant health and economic impact. However, practices related to screening for immunity and immunization of health care personnel (HCP) for varicella vary widely.

METHODS

A decision tree model was built to evaluate the cost-effectiveness of 8 different strategies of screening and vaccinating HCP for varicella. The outcomes are presented as probability of acquiring varicella, economic impact of varicella per employee per year, and cost to prevent additional cases of varicella. Monte Carlo simulations and 1-way sensitivity analyses were performed to address the uncertainties inherent to the model. Alternative epidemiologic and technologic scenarios were also analyzed.

RESULTS

Performing a clinical screening followed by serologic testing of HCP with negative history diminished the cost impact of varicella by >99% compared with not having a program. Vaccinating HCP with negative screen cost approximately $50,000 per case of varicella prevented at the current level of U.S. population immunity, but was projected to be cost-saving at 92% or lower immunity prevalence. Improving vaccine acceptance rates and using highly sensitive assays also optimize cost-effectiveness.

CONCLUSION

Strategies relying on screening and vaccinating HCP for varicella on employment were shown to be cost-effective for health care facilities and are consistent with current national guidelines for varicella prevention.

Susceptibility to measles, rubella, mumps, and varicella-zoster viruses among healthcare workers

BACKGROUND

It is important to identify and immunize susceptible healthcare workers to prevent and control hospital infections. Our aim was to evaluate the specific antibodies against the measles, mumps, and rubella viruses and the varicella zoster virus among healthcare workers in a tertiary-care hospital.

PATIENTS AND METHODS

A total of 284 healthcare workers (89 men and 195 women; mean age, 33.5 ± 11 years), including 111 nurses, 87 physicians, 34 laboratory technicians, and 52 members of the housekeeping staff, of Van Training and Research Hospital were enrolled in this study. Antibodies were detected with an enzyme-linked immunosorbent assay.

RESULTS

The numbers of workers with serological susceptibility to mumps, measles, rubella, or chicken pox were 26 (9.2%), 18 (6.3%), 7 (2.5%), and 5 (1.8%), respectively. Although the difference was not statistical significant, the rate of seroprevalence of antibodies was lowest for measles (90.8%; p>0.05). Susceptibility to measles, mumps, and rubella, and chicken pox was more prevalent among young healthcare workers (p<0.001). Not all healthcare workers born before 1957 were immune to these vaccine-preventable diseases.

CONCLUSION

These data confirm that screening and vaccination of susceptible healthcare workers is essential regardless of age.

[Susceptibility to measles and varicella in healthcare workers in a tertiary hospital in Catalonia]

INTRODUCTION

To estimate the susceptibility to measles and varicella (chickenpox) in healthcare workers in a public tertiary level teaching hospital, in Catalonia.

METHODS

A prevalence study was conducted from January 2006 to December 2008 on 2,752 workers who had serology performed for the determination of measles or varicella by ELISA test during a health examination. Data were analysed by, sex, age, professional category and work unit.

RESULTS

A total of 153 healthcare workers were susceptible to measles and 187 to varicella. The susceptibility of healthcare workers to measles was 6.04% (95% CI: 5.78 to 6.30), and to varicella it was 7.45% (95% CI: 7.14 to 7.75). The highest susceptibility to measles was in resident physicians with 14% (95% CI: 10.8 to 18.5). In high-risk services, where highly immunocompromised patients are attended, the susceptibility of workers was slightly higher than the rest to measles (6.32% vs 5.93%) and varicella (8.34% vs 7.09%). Healthcare workers born after 1980 were 20 times (95% CI: 11.0 to 37.2) more likely to be susceptible to measles, and 2 times (95% CI: 1.2 to 3.2) more likely to be susceptible to varicella than those those born before 1965.

CONCLUSIONS

The susceptibility to measles in healthcare workers in our centre is higher in younger cohorts, with values higher than expected in a community with high vaccination coverage against measles, mumps, rubella vaccine (MMR) in the paediatric population for many years.

Seroprevalence survey of varicella, measles, rubella, and hepatitis A and B viruses in a multinational healthcare workforce in Saudi Arabia

OBJECTIVE

To determine the prevalence of the vaccine-preventable diseases caused by varicella, measles, rubella, and hepatitis A and B viruses in a multinational healthcare workforce.

DESIGN

Prospective cohort study.

SETTING

A 750-bed tertiary care center located in Riyadh, Saudi Arabia.

METHODS

In compliance with hospital policy, newly recruited healthcare workers (HCWs) were enrolled in the study from September 2001 to March 2005. Serum samples were collected from all HCWs during the initial hiring process and tested for IgG antibodies against each of the 5 viral agents. Nonimmune HCWs were subsequently vaccinated at the earliest opportunity.

RESULTS

A total of 4,006 newly hired (international and local) employees were included in the study. All underwent serologic testing for IgG antibodies against varicella, measles, rubella, hepatitis A, and hepatitis B viruses. Of the total, 63% were female and 37% were male. Middle Eastern employees comprised 47% of the total, followed by employees from the Far East (35%), the West (10%), and Africa (8%). Forty-two percent were nurses, 27% were in administration, 18% were medical technicians, and 13% were physicians. Among the 4,006 newly hired HCWs, 14% had negative IgG antibody test results for varicella virus, 13% for measles virus, 10% for rubella virus, 33% for hepatitis A virus, and 43% for hepatitis B virus. More women than men were susceptible to hepatitis A (40% vs. 24%; P<.001), whereas more men were susceptible to hepatitis B (55% vs. 35%; P<.001). Varicella susceptibility was more common among HCWs from the Far East (19%), whereas susceptibility to measles, rubella, hepatitis A, and hepatitis B was highest among HCWs from the Middle East. Both relative youth and male sex were associated with lack of antibodies against hepatitis B virus and rubella virus. In contrast, female sex and younger age were associated with lack of antibodies against hepatitis A virus (P<.001).

CONCLUSION

Seroprevalence surveys of vaccine-preventable diseases among HCWs, although labor intensive, are invaluable in caring for a multinational workforce.

Increased Susceptibility to Varicella‐Zoster Virus among Israeli Physicians and Nurses Born in the Middle‐East Region

Nosocomial transmission of varicella-zoster virus (VZV) is recognized as a significant cause of morbidity in health care workers as well as in high-risk patients. The current study aimed to investigate the presence of VZV antibodies among physicians and nurses, to assess the variables affecting it, and to compare it with previous international studies. Data were obtained by a questionnaire regarding sociodemographic and occupational characteristics and by determination of serum antibodies to varicella-zoster. The seroprevalence of varicella-zoster among the 335 study participants was 94.8% (95%CI: 91.9%-96.9%), with no significant difference between nurses (94%) and physicians (97%). Decreased risk for the virus was observed in workers who immigrated to Israel from the Asia or Africa (OR=0.15; 95% CI: 0.04-0.51). Reduced immunity among these workers remained significant in a multivariate model, which also included age, gender, years of education, number of siblings, and crowding at childhood. Our data suggest that in spite of the high immunity among Israeli physicians and nurses in general, the implementation of small-scale vaccination programs aimed at workers from warmer and tropical areas, should be seriously considered.

Cost-effectiveness of varicella vaccination of healthcare workers

OBJECTIVE

Although transmission of VZV is recognized as an important cause for morbidity in health care workers (HCWs), there is no general agreement on the recommended immunization policy. This study aimed to evaluate several of such prevention policies in economic terms.

SETTINGS

Analysis of the cost per avoided future varicella cases among HCWs in Israel.

METHODS

A cost-effectiveness analysis was performed by comparing the cost per avoided case of varicella among a theoretical cohort of 63,353 physician and nurses aged less than 45 years in Israel. Four policies were examined: (a) do nothing (status quo); (b) vaccination of susceptible workers using VZV serotesting; with (c) or without anamnestic history of chickenpox; and (d) presumptive mass vaccination of all eligible workers. A Markov-based model was developed using data from our recent seroepidemiological study in target population and from the literature.

RESULTS

Screening and vaccination of susceptible workers using anamnestic selection is expected to reduce future cases, within 20 years since vaccination, from 58.3 to 33.0 with an incremental cost of 23,713 US dollars per avoided cases. Using only serological tests to detect susceptible workers would prevent additional 5.7 cases with an incremental cost of 206,692 US dollars per avoided case. Vaccinating all HCWs without serotesting, raises the costs markedly, with almost identical effectiveness, resulting in an incremental cost of 10.4 million US dollars per avoided case. Sensitivity analyses do not alter the ranking of the options.

CONCLUSION

From the employer's perspective, routine varicella vaccination program for HCWs with or without selection of susceptible workers is extremely expensive compared to other high-cost practiced approaches. Substantial reduction in cost of vaccination may alter this conclusion.

Screening healthcare workers for varicella-zoster virus: can we trust the history?

OBJECTIVE

To determine the relationship between immunity and a history of chickenpox based on a self-administered questionnaire.

METHODS

We investigated immunity to varicella-zoster virus in a cohort of newly recruited employees with different job categories and different nationalities using enzyme-linked immunosorbent assay IgG.

RESULTS

There were 1,058 new recruits. Of these, 890 (84%) were immune and 168 (16%) were susceptible. The susceptibility rate was 23% (n = 77) for Asian, 15% (n = 14) for South African, 13% (n = 66) for Middle Eastern, and 9% (n = 11) for Western employees. Physicians were more likely to be immune (93%) than were nurses (85%), medical technicians (75%), or administrative clerks (84%). Seropositivity was not affected by age or gender. The positive predictive value of a history of chickenpox for the seropositivity was 89% (511 of 574); the negative predictive value was 22% (105 of 484). History of chickenpox had a sensitivity of 57% (511 of 890) and a specificity of 63% (105 of 168).

CONCLUSIONS

The varicella-zoster virus seroprevalence among new employees was low, posing an important risk to existing employees and patients. Positive or negative history of chickenpox was an unreliable indicator of susceptibility among healthcare workers of different nationalities. Serologic screening of all employees and vaccination of those susceptible was recommended.

Varicella zoster antibodies in healthcare workers from two neonatal units in São Paulo, Brazil—assessment of a staff varicella policy

Although frequently reported in the literature, a staff varicella policy is not standard in many hospitals even in developed countries. In the present study, we assessed varicella zoster immunity in staff from two neonatal units from hospitals in São Paulo, Brazil. Ninety-seven percent of all staff working in both units agreed to participate. A simple and cost-effective varicella policy was subsequently set up, based on costs and data from serology and a history of previous varicella infection. Our results confirm that a varicella vaccination programme can be implemented in a healthcare facility, even in developing countries.

Varicella and paediatric staff: current practice and vaccine cost-effectiveness

This study was undertaken to audit staff varicella policy for UK paediatric centres, and to estimate the cost-effectiveness of implementing a staff varicella vaccine policy. A telephone survey of 22 hospitals was performed to determine the policy regarding varicella immune status among healthcare workers (HCWs). All hospitals surveyed except one recorded immune status of informed HCWs, and had a policy of exclusion from work if they developed chickenpox. The total cost of vaccine implementation for nurses at the John Radcliffe Hospital neonatal unit over 5 years was estimated at 1601 pounds sterling versus 2474 pounds sterling for the estimated total cost of varicella exposure. Therefore it is likely that vaccination represents a cost-effective intervention.