A Cluster of Primary Varicella Cases Among Healthcare Workers With False-Positive Varicella Zoster Virus Titers

2003 ◽  
Vol 24 (3) ◽  
pp. 202-206 ◽  
Author(s):  
Amy Behrman ◽  
D. Scott Schmid ◽  
Anne Crivaro ◽  
Barbara Watson
Keyword(s):  
Varicella Zoster Virus ◽  
False Positive ◽  
Healthcare Workers ◽  
Screening Program ◽  
Varicella Vaccine ◽  
Varicella Zoster ◽  
Control And Prevention ◽  
Serologic Screening ◽  
Positive Results

AbstractBackground:Five cases of primary varicella zoster virus (VZV) were diagnosed among hospital healthcare workers (HCWs). All had complied with a pre-employment VZV screening program and had been considered immune.Objectives:To summarize the investigation of VZV among un-immunized HCWs and to provide recommendations for avoiding false-positive serologic tests.Design:Risk of transmission of VZV to susceptible HCWs is minimized through serologic screening. Varicella vaccine is recommended for susceptible HCWs. A commercially available latex bead agglutination assay (LA) is widely used because it is rapid and easy to perform. LA was compared with the whole-cell varicella ELISA standardized in the Centers for Disease Control and Prevention (CDC) National Herpes Laboratory.Setting/Population:Large inner-city, tertiarycare hospital with a diverse employee population.Results:In a year, 5 HCWs presented with laboratory-confirmed primary varicella infection. Four had VZV exposures 2 weeks prior to presentation. All had documented positive VZV titers by LA performed at hire. None were offered VZV vaccination. The original LAs were judged false-positives.Intervention/Follow-Up Investigation:Fifty-three consecutive VZV LA samples from the hospital laboratory were retested at the CDC. Forty-four samples concurred. Of the remaining 9, 4 were positive by hospital LA but negative by CDC IgG ELISA. Four were equivocal by hospital LA but negative by CDC IgG ELISA and LA. One was positive by hospital LA but negative by LA and equivocal by ELISA at the CDC.Conclusion:LA may be prone to false-positive results and inappropriate for screening hospital HCWs.

Screening Healthcare Workers for Varicella-Zoster Virus: Can We Trust the History?

2004 ◽  
Vol 25 (7) ◽  
pp. 595-598 ◽  
Author(s):  
Maha Almuneef ◽  
Ziad A. Memish ◽  
Mostafa F. Abbas ◽  
Hanan H. Balkhy
Keyword(s):  
Varicella Zoster Virus ◽  
Predictive Value ◽  
Healthcare Workers ◽  
Middle Eastern ◽  
Enzyme Linked Immunosorbent Assay ◽  
New Employees ◽  
Varicella Zoster ◽  
History Of ◽  
Serologic Screening ◽  
New Recruits

AbstractObjective: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.

scholarly journals Long -Term Persistence of Antibodies Against Varicella in Fully Immunized Healthcare Workers: An Italian Retrospective Cohort Study

2021 ◽  
Author(s):  
Francesco Bianchi ◽  
Silvio Tafuri ◽  
Angela Larocca ◽  
Cinzia Germinario ◽  
Pasquale Stefanizzi
Keyword(s):  
Varicella Zoster Virus ◽  
Healthcare Workers ◽  
Varicella Vaccine ◽  
Serious Adverse Events ◽  
Biological Risk ◽  
Varicella Zoster ◽  
Vaccine Booster ◽  
History Of ◽  
Study Population

Abstract Background. Chickenpox is a highly contagious disease caused by the varicella zoster virus (VZV), and in infants, adolescents, adults, pregnant women, and the immunocompromised it can be serious. The best way to prevent chickenpox is immunization with the varicella vaccine. Protective levels of antibodies induced by the varicella vaccine decline over time, but there is currently no formal recommendation for testing anti-varicella zoster virus (VZV) IgG levels in immunized healthcare workers (HCWs). Methods. The aims of this study were to evaluate the seroprevalence of circulating anti-VZV IgG in a sample a sample of students and residents of the medical school of the University of Bari, the long-term immunogenicity of the varicella vaccine, and the effectiveness of a strategy consisting of a third vaccine booster dose. The study population was screened as part of a biological risk assessment conducted between April 2014 and October 2020. A strategy for the management of non-responders was also examined. Results. The 182 students and residents included in the study had a documented history of immunization (two doses of varicella vaccine). The absence of anti-VZV IgG was determined in 34% (62/182; 95%CI=27.2–41.4%), with serosusceptibility more common among males than females (p<0.05). After a third varicella dose, seroconversion was achieved in 100% of this previously seronegative group. No serious adverse events were recorded. Conclusions. One-third of the study population immunized against VZV lacked a protective antibody titer, but a third dose of vaccine restored protection. Since it is highly unlikely that VZV will be eliminated in the immediate future, the loss of immunity in a substantial portion of the population implies a risk of varicella outbreaks in the coming years. Screening for varicella immunity in routine assessments of the biological risk of medical students and HCWs may help to prevent nosocomial VZV infections.

scholarly journals Long -term persistence of antibodies against varicella in fully immunized healthcare workers: an Italian retrospective cohort study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Francesco Paolo Bianchi ◽  
Silvio Tafuri ◽  
Angela Maria Vittoria Larocca ◽  
Cinzia Annatea Germinario ◽  
Pasquale Stefanizzi
Keyword(s):  
Varicella Zoster Virus ◽  
Healthcare Workers ◽  
Varicella Vaccine ◽  
Serious Adverse Events ◽  
Biological Risk ◽  
Varicella Zoster ◽  
Vaccine Booster ◽  
History Of ◽  
Study Population

Abstract Background Chickenpox is a highly contagious disease caused by the varicella zoster virus (VZV), and in infants, adolescents, adults, pregnant women, and the immunocompromised it can be serious. The best way to prevent chickenpox is immunization with the varicella vaccine. Protective levels of antibodies induced by the varicella vaccine decline over time, but there is currently no formal recommendation for testing anti-varicella zoster virus (VZV) IgG levels in immunized healthcare workers (HCWs). Methods The aims of this study were to evaluate the seroprevalence of circulating anti-VZV IgG in a sample a sample of students and residents of the medical school of the University of Bari, the long-term immunogenicity of the varicella vaccine, and the effectiveness of a strategy consisting of a third vaccine booster dose. The study population was screened as part of a biological risk assessment conducted between April 2014 and October 2020. A strategy for the management of non-responders was also examined. Results The 182 students and residents included in the study had a documented history of immunization (two doses of varicella vaccine). The absence of anti-VZV IgG was determined in 34% (62/182; 95%CI = 27.2–41.4%), with serosusceptibility more common among males than females (p < 0.05). After a third varicella dose, seroconversion was achieved in 100% of this previously seronegative group. No serious adverse events were recorded. Conclusions One-third of the study population immunized against VZV lacked a protective antibody titer, but a third dose of vaccine restored protection. Since it is highly unlikely that VZV will be eliminated in the immediate future, the loss of immunity in a substantial portion of the population implies a risk of varicella outbreaks in the coming years. Screening for varicella immunity in routine assessments of the biological risk of medical students and HCWs may help to prevent nosocomial VZV infections.

Varicella-Zoster Virus (Varicella and Shingles)

2021 ◽  
Author(s):  
Anne Gershon
Keyword(s):  
Varicella Zoster Virus ◽  
Varicella Vaccine ◽  
The United States ◽  
Primary Immune Response ◽  
Wild Type Virus ◽  
High Dose ◽  
Healthy Children ◽  
Zoster Vaccine ◽  
Live Attenuated Vaccine ◽  
Varicella Zoster

A live attenuated vaccine against varicella (later also used to prevent zoster) was developed in 1974 by Takahashi and colleagues. Varicella vaccine was licensed for universal immunization of healthy children in the United States in 1995. It is also now used for this purpose in at least 15 additional countries all over the world. Varicella is disappearing in the US. Varicella vaccine has proven extremely safe and side effects are unusual, mild, and less serious than varicella or its complications. 85% of children are protected completely after 1 dose; the 15% who develop varicella despite immunization usually (but not always) have mild infections. These 15%, however, can transmit the wild type virus to others. Therefore, for optimal effect, 2 doses are required, mostly to address children who did not have an optimal primary immune response after the first dose. Waning immunity does not seem to pose a serious problem, but surveillance of vaccinees is continuing. It was demonstrated in 2005 that at a high dose of vaccine – 15 times higher than that used for prevention of varicella in children - zoster in adults can also be safely prevented. The live attenuated zoster vaccine is effective in approximately 50% of healthy individuals over age 60 who have had varicella in the past, and therefore have latent infection with varicella-zoster virus. It is given as one dose, but its effect runs out about 8 years after vaccination. In 2017, a new vaccine against zoster was also introduced. This is a subunit vaccine which does not contain contagious virus. It is even more effective than the older zoster vaccine and is over 95% effective in adults 50–≥70 years of age in preventing zoster and post herpetic neuralgia.

Chromogranin a Measurement in Metastatic Well-Differentiated Gastroenteropancreatic Neuroendocrine Carcinoma: Screening for False Positives and a Prospective Follow-Up Study

2011 ◽  
Vol 26 (2) ◽  
pp. 94-101 ◽  
Author(s):  
Delphine Vezzosi ◽  
Thomas Walter ◽  
Agnès Laplanche ◽  
Jean Luc Raoul ◽  
Clarisse Dromain ◽  
...  
Keyword(s):  
False Positive ◽  
Chromogranin A ◽  
Morphological Changes ◽  
Surrogate Marker ◽  
False Positive Result ◽  
Gastroenteropancreatic Neuroendocrine Tumors ◽  
Follow Up Study ◽  
Well Differentiated ◽  
Positive Results

Background Multiple causes of false-positive chromogranin A (CgA) measurement have been reported that may affect its impact as a surrogate marker of RECIST progression in well-differentiated gastroenteropancreatic neuroendocrine tumors (WDGEPNET). Aims 1) To evaluate the frequency of false-positive CgA results. 2) To prospectively compare CgA variations with RECIST morphological changes in patients without known causes of false-positive CgA measurements. Methods First, the conditions responsible for potentially false-positive CgA measurements were screened in 184 consecutive patients with metastatic WDGEPNET. Secondly, a variation in CgA at a 6-month interval was compared to RECIST results at 6 months in 46 patients. Results Among 184 patients, elevated CgA was found in 130 cases (71%) including 99 patients with at least one cause of a false-positive result. Impaired kidney function as well as medication with proton pump inhibitors were found to be the 2 major causes of false-positive results. The sensitivity and specificity of CgA measurements compared with morphological tumor changes according to the RECIST criteria were 71% and 50%, respectively, at 6 months. Conclusion Routine screening for the causes of false-positive CgA measurements is mandatory in WDGEPNET patients. Our study does not validate the use of CgA as a surrogate marker of tumor progression.

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