The protests shaking the country since last week – and the police response to them – threaten to thwart efforts to contain the coronavirus outbreak just as it seemed they were finally controlling it in the United States. It is vital that people who catch it remember who they were in contact with so they can alert others and also to try to determine who caught them. But in massive concentrations, it is almost impossible to list the people with whom you came in contact. That process, on the other hand, depends largely on something that may be in short supply: Trust in government. “This going on compromises the trust that is needed,” said Sandro Galea, dean of the Boston University School of Public Health. “If we don’t have that, I’m afraid our ability to contain the virus will be limited.”