Persistent urinary antigen excretion in infants vaccinated with Haemophilus influenzae type b capsular polysaccharide conjugated with outer membrane protein from Neisseria meningitidis
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J G Goepp1, M Hohenboken, J Almeido-Hill
1Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Insights
Urinary antigen tests may show positive results for up to 30 days after Haemophilus influenzae type b conjugate vaccination in infants. Physicians should not use these tests to diagnose invasive disease in vaccinated infants during this period.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Haemophilus influenzae type b (Hib) is a significant cause of invasive bacterial disease in infants.
- Conjugate vaccines, such as PedvaxHIB, are highly effective in preventing Hib infections.
- Urinary antigen detection is a diagnostic tool for invasive bacterial infections.
Purpose of the Study:
- To evaluate the duration of urinary capsular polysaccharide antigen excretion following vaccination with a Hib conjugate vaccine.
- To determine the reliability of urinary antigen tests for diagnosing Hib disease in infants post-vaccination.
Main Methods:
- Urine samples were collected from 40 Navajo infants aged four months who received PedvaxHIB vaccine.
- A control group of 12 infants received a placebo.
- Urine samples were analyzed for Hib antigen at multiple time points up to 30 days post-injection.
Main Results:
- All vaccine recipients excreted Hib antigen in their urine for a median of 14 days post-vaccination.
- Positive antigen excretion was detected in 41-89% of vaccinees between Day 1 and Day 30.
- Placebo recipients showed significantly lower rates of positive urinary antigen tests.
Conclusions:
- Vaccination with Hib conjugate vaccine leads to prolonged urinary antigen excretion.
- Urinary antigen detection tests are unreliable for diagnosing invasive Hib disease in infants for at least 30 days after vaccination.
- Alternative diagnostic methods are necessary for infants presenting with suspected invasive disease within 30 days of receiving the Hib conjugate vaccine.
Abstract:
Testing for urinary excretion of capsular polysaccharide antigen was carried out in 40 four-month-old Navajo infants who had received injections of a Haemophilus influenzae type b Neisseria meningitidis outer membrane protein conjugate vaccine (PedvaxHIB; Merck, Sharp and Dohme Research Laboratories) as part of an ongoing efficacy trial of the vaccine. Urine from 12 placebo recipients was also analyzed. Urine samples were collected on the day of injection (the first voided urine following the injection) and 3, 7, 10, 14, 21 and 30 days later. All vaccine recipients had at least 1 positive specimen. Vaccine recipients excreted antigen for a median period of 14 days after injection. On the first day 54% of vaccinees excreted antigen. Antigen was excreted by 89% of vaccinees on Day 3, 79% on Day 7, 82% on Day 10, 64% on Day 14, 56% on Day 21 and 41% on Day 30. Urine from placebo recipients tested positive in 12% on Day 1, 18% on Day 3, none on Day 7, 14% on Day 10, 11% on Day 14, 10% on Day 21 and none on Day 30. The rate of positive test results was significantly higher among vaccine recipients than among controls. Physicians should not rely on urinary antigen detection tests for predicting the presence of invasive disease caused by H. influenzae type b in infants for at least 30 days after injections with this conjugate vaccine, and possibly longer.