Inoculation Age of Bacillus Calmette-Guérin Tokyo-172 Strain and Vaccine-related Adverse Reactions in Taiwan Birth Cohort of 2012–2017

Abstract

Abstract Background In 2016 in Taiwan, inoculation with the Bacillus Calmette-Guérin (BCG) Tokyo-172 vaccine was postponed from 24 hours after birth to 5–8 months of age. We reviewed BCG-induced adverse reactions reported to the Vaccine Injury Compensation Program (VICP) to identify differences between early and delayed BCG inoculation. Methods Clinical presentations of BCG-related adverse reactions reported to VICP for the 2012–2017 birth cohort were reviewed until the end of 2019. The correlations between inoculation age and complications were evaluated. Results We analyzed 233 BCG adverse reactions, including regional lymphadenitis (33.9%), injection site reactions (35.2%), osteitis/osteomyelitis (27.9%), and distant soft tissue infections (3.0%). The incidence of osteitis/osteomyelitis was lower when vaccination was done after 5 months of age (relative risk [RR], 0.32; 95% confidence interval [CI], .16–.64). Injection site reactions (RR, 8.82; 95% CI, 5.04–15.44) and lymphadenitis (RR, 2.24; 95% CI, 1.44–3.45) were significantly more common in vaccinees older than 5 months. Shorter onset durations of mild adverse reactions (lymphadenitis and injection site reactions) were reported in vaccinees older than 5 months, while no statistical significance was found regarding osteitis/osteomyelitis. Conclusions Osteomyelitis and distant soft tissue infection may occur less frequently when BCG inoculation occurs after 5 months of age, although mild adverse reactions can be more frequent, symptom onset times can be shortened. As few severe reactions might occur more than 2 years after BCG inoculation and the policy of delayed BCG inoculation was implemented in 2016, a longer observational period is needed to clarify the exact severe complications decrement.