Which country's government will be the most affected by the COVID-19 global pandemic, and be the first to go bankrupt, and default?
In my opinion, countries in the top poor and not having drastic measures to prevent pandemic in the first place are likely to go bankrupt and default first. They don't have enough human and financial resources to fight for a long time, before major countries (countries can help them) quell the epidemic and the world economy temporarily recover.
Good thing they are not hit hard now compared to the big countries, like the top 3 countries which has the highest cases, they are rich countries so they can handle the situation, once they find the vaccine, the poor countries will also benefit, so the poor countries measures now should be very strict to avoid a significant increase which they might be able to handle in the long run.