By CARLA K. JOHNSON
AP Medical Writer
The United States has improved its surveillance system for tracking new coronavirus variants such as omicron, boosting its capacity by tens of thousands of samples since early this year. The U.S. got a slow start compared to other nations where labs were conducting genetic sequencing on many more virus samples. Now, federal money is revving up the U.S. efforts. Scientists are able to find and track new versions of the coronavirus by analyzing the genetic makeup of a portion of samples that test positive. Government-run labs, universities and commercial labs then share the data in a global endeavor to monitor for new, potentially dangerous variants.