This systematic review and meta-analysis aimed to recalculate the
efficacy of these two vaccine strains, and to discuss the main variables
associated with controlled trials to evaluate bovine brucellosis
vaccines efficacy. The most used vaccine strain was S19, at the dose of
10 colony forming units (CFU), followed by the
vaccine strain RB51 at 10 CFU. The most used
challenge strain was B. abortus 2308, at the dose of 10
CFU by intraconjunctival route. For the
meta-analysis, trials were grouped according to the vaccine strain and
dose to recalculate protection against abortion (four groups) or
infection (five groups), using pooled risk ratio (RR) and vaccine
efficacy (VE). For protection against abortion (n = 15 trials), S19
vaccine at 10 CFU exhibited the highest protection
rate (RR = 0.25, 95% CI: 0.12 to 0.52; VE = 75.09%, 95% CI: 48.08 –
88.05), followed by RB51 10 (RR = 0.31, 95% CI:
0.16 to 0.61; VE = 69.25%, 95% CI: 39.48 – 84.38). For protection
against infection (n = 23 trials), only two subgroups exhibited
significant protection: S19 at 10 CFU (RR = 0.28,
95% CI: 0.14 to 0.55; VE = 72.03%, 95% CI: 57.70 – 81.50) and RB51
at 10 CFU dose (RR = 0.43, 95% CI: 0.22 to 0.84;
VE = 57.05%, 95% CI: 30.90 – 73.30). In conclusion, our results
suggest that the dose of 10 CFU for S19 and 10
CFU for RB51 are the most suitable for the
prevention of abortion and infection caused by B. abortus.
Efficacy of Brucella abortus S19 and RB51 vaccine strains: a systematic review and meta-analysis
