Inadequate Titers Research Articles

Immune response to rabies post-exposure prophylaxis in patients with non-HIV secondary immunodeficiencies

BackgroundThis study sought to determine the proportion of individuals with non-HIV secondary immunodeficiencies presenting inadequate antibody titers after rabies post-exposure prophylaxis (PEP) and to identify variables associated with inadequate response. MethodsA retrospective review of the records of immunocompromised patients having received a full course of PEP after a rabies exposure and having been tested for post-PPE antibody titers in two French Antirabies Clinics, between 2013 and 2018, was conducted. Antibody titers < 0.5 EU/ml (ELISA) were classified as inadequate. ResultsA total of 28 individuals were included, 6 had inadequate post-PPE titers. None of the tested variable was independently associated with inadequate titers. ConclusionsInadequate response was unpredictable and not explained either by the characteristics of patients or by the PEP regimen they received. These findings support the WHO recommendation to systematically assess post-PEP response in immunocompromised patients to detect non-responders, who might require an additional dose.

Role of carriers in the transmission of pneumonia in bighorn sheep (Ovis canadensis)

ABSTRACTIn the absence of livestock contact, recurring lamb mortality in bighorn sheep (Ovis canadensis) populations previously exposed to pneumonia indicates the likely presence of carriers of pneumonia-causing pathogens, and possibly inadequate maternally derived immunity. To investigate this problem we commingled naïve, pregnant ewes (n=3) with previously exposed rams (n=2). Post-commingling, all ewes and lambs born to them acquired pneumonia-causing pathogens (leukotoxin-producing Pasteurellaceae and Mycoplasma ovipneumoniae), with subsequent lamb mortality between 4-9 weeks of age. Infected ewes became carriers for two subsequent years and lambs born to them succumbed to pneumonia. In another experiment, we attempted to suppress the carriage of leukotoxin-producing Pasteurellaceae by administering an antibiotic to carrier ewes, and evaluated lamb survival. Lambs born to both treatment and control ewes (n=4 each) acquired pneumonia and died. Antibody titers against leukotoxin-producing Pasteurellaceae in all eight ewes were ‘protective’ (>1:800 and no apparent respiratory disease); however their lambs were either born with comparatively low titers, or with high (but non-protective) titers that declined rapidly within 2-8 weeks of age, rendering them susceptible to fatal disease. Thus, exposure to pneumonia-causing pathogens from carrier ewes, and inadequate titers of maternally derived protective antibodies, are likely to render bighorn lambs susceptible to fatal pneumonia.

Incidence and variables associated with inadequate antibody titers after pre-exposure rabies vaccination among veterinary medical students

BackgroundThis study sought to determine the proportion of subjects with inadequate antibody titers at two years after pre-exposure rabies vaccination and identify variables associated with inadequate antibody titers. MethodsA retrospective chart review of vaccination records of veterinary students in Michigan, 2004–2009, was conducted. Antibody titers <0.5IU/ml as estimated by rapid fluorescent focus inhibition test were classified as inadequate. Variables were compared between the two groups to identify factors associated with inadequate titers at two years. ResultsA total of 603 subjects (mean age 24.1±4.2 years, male:female 106:497) were included. Nearly one third (177/603, 29.4%) had inadequate titers at two years. Male gender (adjusted odds ratio (AOR) 1.87, 1.07–3.27; p=0.029), vaccine manufacturer (AOR 1.49, 1.16–1.92; p=0.002), BMI >25 (AOR 1.61, 1.02–2.54; p=0.043), and duration between first and third doses of vaccine >21 days (AOR 2.49, 1.26–4.97; p=0.009) were independently associated with inadequate titers. ConclusionsTwenty-nine percent of subjects had inadequate antibody titers against rabies at 2 years. Gender, vaccine type/manufacturer, BMI of 25 or greater, and more than 21 days between the first and third doses of vaccine were independently associated with inadequate antibody titers at two years. Our data would support modifying the recommendations, so the third dose is recommended at 21 days rather than 21–28 days.

Four-year follow up of hepatitis C patients vaccinated against hepatitis B virus

Patients with chronic hepatitis C have been recommended to receive vaccinations against hepatitis B. Our study aimed at evaluating the hepatitis B immunogenicity and efficacy against hepatitis B virus infection 4 years after primary immunization series in a group of patients with chronic hepatitis C. We recruited 36 out of 48 hepatitis C virus (HCV) infected individuals who were vaccinated against hepatitis B virus (20 mug of recombinant HBsAg at 0-1-6 mo schedule) in 1998. Here we measured anti-HBs titers and anti-HBc 4 years after delivery of the third dose of primary immunization series. After 4 years a total of 13/36 (36%) HCV infected patients had seroprotective titers of anti-HBs compared with 9/10 (90%) in the control group, (P<0.05). Similarly the mean concentration of anti-HBs found in hepatitis C patients was significantly lower than that found in healthy subjects (18.3 and 156.0 mIU/mL respectively (P<0.05). None of the HCV infected patients or controls became infected with HBV during the study period as confirmed by anti-HBc negativity. We demonstrated that 4 years after HBV immunizations' more than 60% of vaccinated HCV patients did not maintain seroprotective levels of anti-HBs, which might put them at risk of clinically significant breakthrough infections. Further follow-up studies are required to clarify whether memory B and T lymphocytes can provide protection in chronic hepatitis C patients in the absence or inadequate titers of anti-HBs.

Immunization Status of Internationally Adopted Children

To the Editor. Many internationally adopted children arrive in the United States with incomplete or uncertain vaccination status. Some have suggested that even children who have received adequate numbers of vaccines for tetanus and polio have inadequate titers, resulting from poor immunogenicity of the vaccines, impaired immune responses (possibly attributable to malnutrition), or incorrect records.1,,2 Some physicians recommend revaccinating all international adoptees at arrival in the United States.3We …

Immune status of children one to four years of age as determined by history and antibody measurement.

Measurement of serum antibody levels in children one to four years old, living in three city and one suburban census tract, revealed that 63 per cent of the total study population were susceptible to rubella and approximately 33 per cent had inadequate titers of measles antibody. Antitoxin levels to diphtheria and tetanus were low in 24 and 7 per cent respectively of the entire study group. A large proportion (57 per cent) of these children had serum antibody levels of less than 10 to one or more types of poliovirus. Many had low antibody levels after the recommended number of immunizations; others had not received adequate poliomyelitis vaccine. Although those with low levels may not contract paralytic disease, if reinfected with wild poliovirus, they may spread the infectious agent to susceptible persons in the environment. Increased effort should be made to immunize all preschool children. Advisory committees should consider the need for periodic reimmunization. (N Engl J Med 289:231–235, 1973)