We analyze whether central bank credit lines and government-backed guarantees helped mitigate the impact of the pandemic's sudden stop, marked by the abrupt withdrawal of international capital, using administrative data on the universe of Chilean firms. Our regression discontinuity design reveals that eligible firms increased domestic borrowing at lower costs. These policies reduced the cost of domestic debt compared to foreign debt, easing access to capital. An open economy model explains the complementarity of both interventions--credit lines and guarantees--in relaxing collateral constraints, reducing financial intermediaries' risk aversion and boosting domestic credit supply amidst shrinking international flows.