If you are an expatriate living in the US, additional medical coverage should be purchased for the period that you will be in the country. You will want to ensure this coverage protects you in case of an accident, a medical emergency as well as repatriation. You should investigate if you will need this insurance before entering the country and if the insurance needs to come from your home country, the U.S. or both!
Health insurance in the United States is any program that helps pay for medical expenses, whether through privately purchased insurance, social insurance, or a social welfare program funded by the government. Synonyms for this usage include "health coverage", "health care coverage", and "health benefits". In a more technical sense, the term "health insurance" is used to describe any form of insurance providing protection against the costs of medical services. This usage includes private insurance and social insurance programs such as Medicare, which pools resources and spreads the financial risk associated with major medical expenses across the entire population to protect everyone, as well as social welfare programs like Medicaid and the Children's Health Insurance Program, which both provide assistance to people who cannot afford health coverage.