E-poster presented during the Union World Conference 2020.
Y. Smit, E.W. Tiemersma, N.T. Huong, N.V. Nhung, F. Cobelens, P.T. Pelzer, KNCV Tuberculosis Foundation.
Background
- BCG is known to prevent TB in young children ▪ Evidence for protection by BCG vaccination against Mtb infection is controversial
- A similar study in Tanzania found children with a BCG scar had lower odds of tuberculn skin test (TST) positivity than children without BCG scar
- Protection of BCG against Mtb may vary according to geographical latitude
Methods
- Secondary analysis of tuberculin surveys amongst Vietnamese schoolchildren,1988 – 2001
- Aim was to examine the association between BCG and Mtb ascertained by TST, adjusting for BCG-induced variation by applying different cut-off values for a positive TST
Results
- Figure displays OR for the association between BCG and TST positivity 10-26 mm in 3 different regions of Vietnam
- The trend for the OR with increasing induration cut-off was significantly different in the South’
- The OR did not drop below 1 with any induration cut-off, i.e. there was no inverse association between BCG vaccination and TST induration size
Discussion
- We found no inverse association of BCG against Mtb infection as ascertained by TST, indicating no protective direction of the association between BCG and Mtb
- These findings are unexplained and may be ascribed to geographical differences and high prevalence of Beijing genotype in Vietnam. Beijing genotype has been associated with reduced IGRA conversion among BCG vaccinated