If there’s an H1N1 swine flu pandemic, vaccine makers should be able to churn out “at least” 1 billion to 2 billion doses of H1N1 swine flu vaccine within four to six months, the World Health Organization (WHO) estimates.

As of May 6, there were 1893 confirmed cases in 23 countries, including 642 cases in 44 states in the U.S.