Significance of the number of viable units in BCG vaccines

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Protective Efficacy and Pulmonary Immune Response Following Subcutaneous and Intranasal BCG Administration in Mice
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Protective Efficacy and Pulmonary Immune Response Following Subcutaneous and Intranasal BCG Administration in Mice

Published on: September 19, 2016

G Nyerges, M Drinóczy

    Developments in Biological Standardization
    |January 1, 1986
    PubMed

    Insights

    The study found that a stronger Bacillus Calmette-Guérin (BCG) vaccine lot resulted in more suppurative lymphadenitis but similar tuberculin positivity compared to a weaker lot in newborns. This impacts infant vaccination strategies.

    Area of Science:

    • Immunology
    • Pediatrics
    • Vaccinology

    Background:

    • Bacillus Calmette-Guérin (BCG) vaccination is crucial for preventing tuberculosis in infants.
    • Different BCG vaccine strengths may influence post-vaccination outcomes, including adverse reactions and tuberculin sensitivity.
    • Understanding the relationship between vaccine strength and adverse events is vital for public health.

    Purpose of the Study:

    • To determine the incidence of suppurative lymphadenitis in newborns vaccinated with BCG vaccines of varying strengths.
    • To investigate the post-vaccination tuberculin positivity in children who received different BCG vaccine strengths.
    • To compare the safety and immunogenicity of two BCG vaccine lots with different viable unit concentrations.

    Main Methods:

    • A study involving 51,000 newborns, divided into two groups based on BCG vaccine strength (2 x 10^5 VU/dose vs. 0.5 x 10^5 VU/dose).
    • Monitoring the incidence of suppurative lymphadenitis in both vaccination groups.
    • Conducting tuberculin tests (RT-23) two years post-vaccination to assess immune response.

    Main Results:

    • The incidence of suppurative lymphadenitis was significantly higher in the group receiving the stronger BCG vaccine (6.84 per 1,000) compared to the weaker vaccine group (0.87 per 1,000).
    • Tuberculin positivity rates were 19.8% in children who received the stronger vaccine and 16.4% in those who received the weaker vaccine.
    • While the stronger vaccine increased lymphadenitis, the difference in tuberculin positivity was less pronounced.

    Conclusions:

    • BCG vaccine strength influences the risk of suppurative lymphadenitis in newborns.
    • The stronger BCG vaccine lot demonstrated a higher rate of local adverse reactions.
    • Both vaccine strengths induced comparable levels of tuberculin positivity two years after vaccination, suggesting similar long-term efficacy.

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