OTTAWA—The Bank of Canada says the national economy will go in reverse for the first quarter of 2021, hammering the hardest-hit workers again on the path to a recovery that rests on the rollout of vaccines. Workers in high-contact service industries will carry the burden of a new round of lockdowns, which the central bank warns will exacerbate the pandemic’s uneven effects on the labour market. As a result, the bank announced it is keeping its key interest rate on hold at 0.25 percent, citing near-term weakness and the “protracted nature of the recovery” in its reasoning. But the short-term pain is expected to give way to a brighter outlook for the medium-term with vaccines rolling out sooner than the central bank expected. Still, the bank warns in its updated economic outlook that a complete recovery from COVID-19 will take some time. Nor does the Bank of Canada see inflation …