Medicare and Social Security taxes

I am new to United States on a H1B Visa. This is my first month here. I asked HR about giving me a dummy paycheck so I know how much to expect at the end of the month. On there I saw that Medicare is deducted along with income tax and California state tax. In most likelihood I will not stay here for more than five years. Can I not pay the Medicare each month? Can I claim that back?

The Internal Revenue Service website has information that addresses how wages of most people from other countries who work in the U.S. for American or foreign employers are subject to the same Social Security and Medicare taxes as U.S. citizens. It also discusses what visa types are excluded from these taxes. I’m not an expert in tax law but it looks to me like your type of visa is not excluded. Social Security withholding is 6.2% and Medicare withholding is 1.45%. If you have any other questions about these taxes, I’d talk with your employer’s HR department.
https://www.irs.gov/individuals/international-taxpayers/aliens-employed-in-the-us-social-security-taxes