While the number of confirmed cases of H1N1 flu virus in New York City rose to 62 by late Saturday, health officials reassured the public that all the cases have been mild.

All but three of those cases are associated with St. Francis Prep High School in Fresh Meadows, Queens, according to the city Department of Health.

The school has been closed all week after hundreds of students came down with flu-like symptoms, and an SAT test that was supposed to be held there Saturday was postponed until May 16.

After meeting with state and local leaders on Friday, the school's principal, Brother Leonard Conway said the building has been scrubbed and the ventilation system purified.

"They have purged the air system. We have been running on 100 percent outside air. And 'purging,' I'm told, means the inside air goes outside and the fresh air comes inside," said Conway.

Five of the confirmed cases are from nearby P.S. 177, another Queens school near St. Francis Prep that plans to reopen on Wednesday, according to Mayor Michael Bloomberg.

Of the three confirmed cases of H1N1 virus not connected with St. Francis Prep, two are associated with travel to Mexico, where the particular strand originated and has killed at least 16 people.

Only one confirmed case in the city is neither associated with St. Francis Prep nor Mexican travel.

Another 17 probable cases of H1N1 flu were being tested on Saturday by the Centers for Disease Control, and of those 14 cases are associated with St. Francis Prep.

Bloomberg said the city is doing a great job dealing with the outbreak.

"It looks like we're getting through this in a nice way and I don't detect any fewer people in the subway or in the stores or people canceling trips," said the mayor. "The bottom line is that its safe to come to the city."

"We haven't seen severe illness. That's what we were concerned about," said City Health Commissioner Thomas Frieden. "That doesn't mean we won't, but its reassuring a week into have not seen a single case of severe illness with flu."

By late Saturday, the number of confirmed H1N1 cases nationwide had risen to at least 160 in more than 20 states.

In his weekly address, President Barack Obama said his administration is working aggressively to avoid a potential pandemic.

He said since people have not developed an immunity to the new strain of flu, it has the potential to cause greater harm.

Obama also said he asked Congress for $1.5 billion to buy more medicine and equipment in case they are needed.

"It is my greatest hope and prayer that all of these precautions and preparations prove unnecessary," said the president. "But because we have it within our power to limit the potential damage of this virus, we have a solemn and urgent responsibility to take the necessary steps. I would sooner take action now than hesitate and face graver consequences later."

Obama said the CDC has asked schools and daycare facilities with confirmed cases of the flu virus to close for up to two weeks.

He also urged employers to let any infected workers take off as many sick days as they need to recover.

CDC officials said they were in the process of sending out courses of anti-influenza drugs to 30 states.

"Here in the U.S. we're trying to act aggressively and quickly so that if it does turn out to be a moderate or severe influenza strain, that we're prepared, that we have the resources to treat people, that we can reduce the spread," said Anne Schuchat of the CDC.

The CDC also sent testing kits to states to relieve pressure on its Atlanta office.

In response to the H1N1 outbreak, some airlines are cutting service to Mexico, where more than 350 people have been infected.

Continental Airlines said it would cut its Mexican flights and slash capacity by 50 percent by using smaller aircraft.

As for passengers who want to cancel flights to Mexico they have already booked, Continental is waving change fees until May 31.

United Airlines said it plans to slash its weekly flights for next month by more than half, and Delta said it would also reduce service but by Saturday had not said by how much.

Mexican officials said there were indications the virus has not been nearly as deadly as first thought.

The country's health secretary said Friday that only 16 people had died from H1N1, instead of 150 as previously reported.

But the virus is still spreading around the globe, with more than 700 confirmed cases worldwide by Saturday.

The CDC confirmed Saturday one case of the H1N1 virus in Costa Rica - the first case in Latin America outside of Mexico.

Officials in South Korea and China confirmed those countries' first cases of the virus on Friday.

China had suspended flights from Mexico to Shanghai.