News Blog readers will have read of the hypothesis that withdrawal of vaccination against small-pox exacerbated the HIV epidemic since the antibodies elicited by the small-pox vaccine cross-react with HIV. Other readers know that BCG vaccine (anti-TB) can prove effective against malignant melanoma and other cancers. Kandsomy and colleagues systematically reviewed 77 papers dealing with unintended (non-specific) beneficial effects of common childhood vaccines. Many examples were found where vaccinations against one disease created a biochemical response that should be effective against another. However, clinical effects were not reported, and even the laboratory based results reported were short-term so we do not know how persistent they were. The very next paper in the BMJ tries to answer the clinical question by examining all-cause mortality in clinical trials, cohort studies and case-control studies of vaccines. They found reductions in all-cause mortality greater than could be plausibly attributed to reductions in the targeted disease for BCG and measles vaccines, but the risk appears increased for the ‘triple’ (diphtheria, pertussis and tetanus) vaccine. The reductions in all-cause mortality following measles and BCG vaccination were confirmed when the analysis was restricted to RCTs, so it seems to be real. The issue of the effect of different sequencing regimes are unknown because few high-quality studies have examined this issue.
— Richard Lilford, CLAHRC WM Director
- Weinstein RS, Weinstein MM, Alibek K, Bukrinsky MI, Brichacek B. Significantly reduced CCR5-tropic HIV-1 replication in vitro in cells from subjects previously immunized with Vaccinia Virus. BMC Immunol. 2010; 11: 23.
- Kandasamy R, Voysey M, McQuid F, et al. Non-specific immunological effects of selected routine childhood immunisations: systematic review. 20116; 355: i5225.
- Higgins JPT, Soares-Weiser K, López-López JA, et al. Association of BCG, DTP, and measles containing vaccines with childhood mortality: systematic review. BMJ. 2016; 355: i5170.