Effect of transfusions on serologic testing for antibody to varicella

Risk of Inappropriately Timed Live Vaccination After Pediatric Cardiovascular Surgery

OBJECTIVE

The American Academy of Pediatrics (AAP), Advisory Committee on Immunization Practices (ACIP), and Centers for Disease Control and Prevention (CDC) recommend delaying live vaccinations up to 11 months after transfusions of certain blood products due to the risk of immunoglobulins decreasing immunization efficacy. Because vaccination schedules recommend live immunizations at 12 months, infants aged 5 to 12 months who undergo cardiac surgery requiring blood products are potentially at risk for improper vaccination. The objective of this study was to identify the risk of inappropriately timed live vaccination in pediatric patients after cardiovascular surgery.

METHODS

This single-center, retrospective chart review included 345 patients 5 to 12 months of age who underwent cardiovascular surgery between January 1, 2010, and December 31, 2016. Included patients received packed red blood cells (PRBCs) and/or platelets during the surgical admission and a live vaccine within the first 18 months of life. The primary endpoint was the incidence of live vaccine administration within 7 months of receiving PRBCs and/or platelets.

RESULTS

Of the 345 included patients, 67% (n = 230) were inappropriately vaccinated after receiving platelets and/or PRBCs during cardiac surgery.

CONCLUSIONS

Infants who undergo cardiac surgery between the ages of 5 and 12 months are at risk for inappropriate live vaccination timing. A clinically significant percentage of pediatric patients who received blood products during a cardiac surgical admission later received live vaccines at times that were inconsistent with AAP, ACIP, and CDC recommendations. Future interventions aimed at educating providers and patients may be warranted.

Managing varicella zoster virus contact and infection in patients on anti-rheumatic therapy

Chickenpox and shingles can be more severe and occasionally life threatening in immunosuppressed patients. As such, some groups warrant a more detailed history, serological testing and consideration of prophylaxis following contact with the virus. Active disease may also require more aggressive treatment with antivirals. Guidance for the use of varicella zoster immunoglobulin has recently been updated by Public Health England with important implications for rheumatology patients.

Diphtheria, tetanus, and varicella immunity in health care workers in neonatal units

BACKGROUND

Susceptible health care workers are at risk of acquiring and transmitting vaccine-preventable diseases to or from patients. The objective of this study was to assess antibody levels against diphtheria, tetanus, and varicella in healthcare workers.

METHODS

Antibody levels against diphtheria, tetanus, and varicella were measured in health care professionals in 2 neonatal units at the Federal University of São Paulo, Brazil.

RESULTS

Between September and November 2002, 215 of 222 (96.8%) health care workers were studied. Of those, 122 (56.7%) gave oral information regarding their vaccination status against diphtheria and tetanus and only 9 (4.2%) had their vaccination cards. Geometric mean antibody levels against diphtheria, tetanus, and varicella were 0.89 IU/mL (95%CI, 0.73 to 1.08), 0.86 IU/mL (95%CI, 0.68 to 1.07) and 1.10 IU/mL (95%CI, 0.98 to 1.24), respectively. Using internationally accepted definitions, 200 (93.0%) and 182 (84.7%) individuals had full protection against diphtheria and tetanus, respectively. Regarding varicella, 213 (99.1%) individuals were immune and 2 (0.9%) had equivocal immunity against varicella. Of 65 (30.2%) individuals without previous history of the illness, 63 (96.9%) were immune against varicella zoster virus.

CONCLUSIONS

Based on serologic screening, most professionals were immune to diphtheria, tetanus, and varicella. Absence of previous history of varicella was an unreliable identifier of susceptibility to varicella zoster virus in the health care workers studied.

Fatal varicella zoster virus encephalitis in two patients following allogeneic hematopoietic stem cell transplantation

BACKGROUND

Reduced cellular immunocompetence following allogeneic hematopoietic stem cell transplantation (aHSCT) increases susceptibility to viral infections. Varicella zoster virus (VZV) reactivation in this setting most commonly manifests as dermatomal herpes zoster but in some cases life-threatening VZV encephalitis occurs.

STUDY DESIGN/RESULTS

We describe the cases of two patients who presented with shingles 3 and 18 months, respectively, after HLA-matched peripheral blood stem cell transplantation (PBSCT). Unfortunately, in the further clinical course both patients developed fatal VZV encephalitis, despite initial high-dose intravenous therapy with acyclovir and in one case with additional VZV-immunoglobulin.

CONCLUSION

These two cases suggest that rapid intervention with systemic treatment is warranted and raise the question whether initial combination therapy with intravenous acyclovir and foscarnet, VZV vaccination or long-term low-dose acyclovir are needed to improve treatment and clinical outcome in immunocompromised patients, having undergone allogeneic HSCT.

Effect of transfusion of fresh-frozen plasma on recipients' antibodies to hepatitis B surface antigen and hepatitis B surface antigen status in countries where hepatitis B virus is endemic

BACKGROUND AND OBJECTIVES

Antibodies to hepatitis B virus (HBV) that are passively acquired through transfusions may lead to confusion and inappropriate clinical decisions. We evaluated the effects of transfusing fresh-frozen plasma (FFP) on serological tests for HBV antibodies in patients without such antibodies.

MATERIALS AND METHODS

Tests for HBV surface antigen (HBsAg), and for antibodies to HBV surface antigen (anti-HBs) and HBV core antigen (anti-HBc), were carried out using enzyme immunoassay on the FFP and sera of 50 patients transfused with FFP containing anti-HBs.

RESULTS

After FFP transfusion, the incidences of 'false' positivity for anti-HBs and anti-HBc were 64% (32/50) and 100% (seven of seven), respectively, and of 'false' negativity for HBsAg was 18.8% (three of 16) in previously positive patients. The post-transfusion seropositivity for antibodies results from passive transmission, whereas the inability to detect HBsAg is the result of decreased detectable levels.

CONCLUSIONS

Laboratory staff and clinicians alike should be cautious in interpreting the results of the HBV marker tests in patients who have recently been transfused, and in obtaining specimens for such studies.

Neonatal antibody titers against varicella-zoster virus in relation to gestational age, birth weight, and maternal titer

OBJECTIVE

Varicella-zoster virus (VZV) can cause severe disease in premature neonates. The fetus receives protective maternal VZV-immunoglobulin G (IgG) mainly in the third trimester of pregnancy. Therefore, premature neonates are considered at risk for VZV infection. Administration of varicella-zoster immunoglobulin (VZIG) within 96 hours after exposure effectively prevents severe illness in susceptible patients. The objectives of this study were to define the major determinants of the neonatal VZV-IgG titer and to determine the half-life of transplacentally acquired VZV-IgG. Guidelines provided by the Centers for Disease Control and Prevention for the use of VZIG in (premature) neonates were evaluated.

METHODS

VZV-IgG titers were measured in sera of 221 neonates and 43 mothers using a quantitative enzyme-linked immunosorbent assay. In 27 neonates, VZV-IgG titers were followed for up to 14 weeks.

RESULTS

In a linear regression model, the maternal antibody titer was the major determinant of the neonatal titer (beta = 0.89); gestational age was only of minor importance (beta = 0.18). The median half-life of VZV-IgG in neonates was 25.5 days (range: 14.6-76.0 days). In the first weeks of life, major fluctuations of the VZV-IgG titer occurred in >50% of the neonates. The predictive value of Centers for Disease Control and Prevention guidelines for identification of neonates who should receive VZIG in case of exposure to VZV was poor: positive and negative predictive values were 0.80 and 0.43, respectively.

CONCLUSIONS

The neonatal VZV-IgG titer is predominantly predicted by the maternal VZV-IgG titer, whereas birth weight and gestational age are much less predictive than previously reported.

Active immunization of children with leukemia and other malignancies

Active immunization against measles, Haemophilus influenza B, tetanus, diphtheria, hepatitis B, influenza, poliomyelitis, and, when indicated varicella and pneumococcus induces long-lasting immunologic protection in most healthy pediatric vaccine recipients. Among children receiving immunosuppressive therapy for cancer, possible early loss of specific immunity acquired from prior vaccination or disease, and likely diminished responsiveness to initial or booster vaccination must be considered. In addition, the safety of vaccine administration requires separate study in this population. Published evidence demonstrates preservation of vaccine-induced antibody titers against tetanus, diphtheria, poliomyelitis and (in children treated for lymphoma) pneumococcus. In contrast, prior immunity to varicella, influenza, and hepatitis B (when naturally acquired), and measles (acquired by vaccination) is compromised during and/or after antineoplastic therapy. Studies of immunologic protection acquired by prior vaccination against hepatitis B, varicella, and H influenza have not been published. The safety of administering toxoids and inactivated vaccines in this population is well documented. In contrast, morbidity must be expected if live attenuated vaccines (oral polio vaccine, attenuated measles vaccine or attenuated varicella vaccine) are administered to children receiving anti-cancer therapy. The risks of using live vaccines should be measured against demonstrable benefits in any vaccine program. The response to initial or booster immunizations against tetanus and diphtheria are similar to those in healthy children. For all other immunizations reviewed, responsiveness is diminished during periods of chemotherapy, more strikingly in children treated for leukemia than for solid tumors. Antibody responses to these vaccines range from slightly blunted (in the case of H influenza B) to marginal (influenza) or completely useless (pneumococcus and hepatitis B in children treated for leukemia).