Some 300 people in Hong Kong remain quarantined at a hotel after a guest tests positive for swine flu.
St. Francis Prep School in Queens reopens.
Latest numbers from WHO: More than 1,000 cases, 21 countries, 26 deaths.
The virus has spread to 19 countries, including China. The Chinese government quarantines 70 Mexicans.
Three more people in Mexico die from swine flu overnight. The number of cases in the U.S. jumps more than 25 percent since Saturday night.
Still, health officials say the outbreak may have turned a corner. Mexico's health ministry says it may not be any worse than a normal seasonal flu and says the worst of it has passed.
Italy and Costa Rica become the 16th and 17th countries with confirmed cases of swine flu. There are more than 650 confirmed cases worldwide.
New developments suggest the virus is not as serious as previously thought. Mexico says that of its suspected cases, fewer than half of the people actually had swine flu. Of the more than 300 people that did, 16 died.
The CDC says is encouraged by the news, but will continue preparing for the worst just in case.
In the U.S., there are 160 confirmed cases of swine flu in 21 states. The majority of them did not travel to Mexico.
Dr. Michael J. Ryan, director of the WHO's global alert and response team, says an increase to alert level 6 -- signaling a pandemic -- could be imminent regardless, explaining that "pandemic" suggests the disease's geographic spread as opposed to its severity.
Despite repeated assurances that pork is safe to eat, concerns grow in Canada after pigs there test positive for the virus and that farm is placed under quarantine.
An estimated quarter of a million schoolchildren in the U.S. are out of school. In some cities, officials have closed entire school districts due to a single illness. Besser says a school should only be closed if it has a confirmed case of the flu.
President Obama says the U.S. is still preparing for the worst, but adds that this could end up falling short of a pandemic and run its course just "like ordinary flus."
Head of the CDC's influenza division, Dr. Nancy Cox, says preliminary research suggests the makeup of this virus lacks some key components of the 1918 flu pandemic.
An estimated 160,000 children in the U.S. are out of school in 14 states, including 80,000 students in Fort Worth due to worries about swine flu.
Vice President Joe Biden veers off message, suggesting Americans should take precautions above and beyond those previously suggested by the government. In an interview on NBC's "Today" show, Biden suggests people should avoid mass transit to guard themselves against the flu. Government officials scurry to correct the record.