The U.S. government is committing to purchase an additional 180 million rapid COVID-19 tests for $1 billion, adding to the $2 billion test buying plan it announced in September, a top U.S. health official said on Wednesday. The combined purchases will help quadruple the United States’ test output by December to around 200 million tests per month, Jeff Zients, the White House coronavirus response coordinator, said during a press call. “We’ll continue to pull every lever to expand manufacturing production of tests which will have the impact of driving down the cost per test and making sure that tests are widely available and convenient,” Zients said. The government will also double the number of pharmacies it partners with to provide free COVID-19 tests to 20,000 pharmacies, Zients added. Surging demand for COVID-19 tests from U.S. employers has exacerbated a nationwide shortage of rapid tests in recent weeks and is driving …