Here in Uruguay CoronaVac is head to head with Pfizer in preventing death for those infected, 95% to 94% respectively. It is true that infection prevention rates are way better for Pfizer, at 79% vs CoronaVac's ~63%, but I can't imagine calling that "not very effective".
Source: https://www.gub.uy/ministerio-salud-publica/sites/ministerio...