The flu is continuing to circulate through Clark County, spreading faster and earlier than previous years.The increasing flu activity has health officials urging everyone 6 months and older to get vaccinated and has prompted hospitals to impose visitor limitations to protect patients and staff.For three consecutive weeks, the flu virus has been well above 10 percent positivity in Clark County. That means more than 10 percent of the people reporting flulike symptoms tested positive for the flu.During the week of Dec. 15-21, about 33 percent of tests came back positive. The following week, about 30 percent of tests were positive, and the next week, nearly 44 percent were positive, according to Clark County Public Health.Two types of influenza A — H3N2 and H1N1 — and influenza B strains of the virus have been circulating in communities across the country. The circulating strains are a good match to the strains included in this year’s flu vaccines, according to the Centers for Disease Control and Prevention.The most prominent strain in Clark County, the state and the rest of the country has been H1N1, the 2009 “swine flu” virus that caused a pandemic. H1N1 viruses have continued to circulate since 2009, but this is the first season the virus has circulated at high levels since the pandemic, according to the CDC.