Which countries in the world have seen social security system collapse or major accidents?

In the real world, the development of social security is still very uneven. According to the data provided by the International Labour Organization, at present, only 20% of the people in the world enjoy full security, and 50% of the population does not enjoy social security. The developed countries have relatively sound social security systems, with social security coverage close to 100% and social security expenditure accounting for16-25% of GDP. In middle-income countries, its coverage rate is 20-60%; Africa has the lowest level of social security. In sub-Saharan Africa, the coverage is only 5- 10%, and social security expenditure accounts for 4.3% of GDP. The groups lacking social security are concentrated in the informal sector in developing countries, mainly employees in small workplaces, temporary workers, migrant workers and self-employed, with the largest number of women workers. These groups are either not supported by social security, or the level of social security is low, which can not meet their basic needs such as medical care and old-age care.