It has been a week since news of an international outbreak of the so-called swine flu raised fears of a pandemic with an unknown potential for countless deaths.
But so far, the flu's oink has been worse than its bite.
New York City officials reported Friday that the swine flu still has not spread beyond a few schools, and in Mexico, the suspected origin of the outbreak, very few relatives of flu victims seem to have caught the virus.
As further evidence that this strain of the H1N1 influenza virus is looking a little less ominous, a U.S. health official says it lacks the genes that made the 1918 pandemic strain so deadly.
And a flu expert in New York says there's no reason to believe the new virus is a more serious strain than seasonal flu.
Even so, we aren't in the clear yet. New flu cases are still popping up, from Hong Kong to Pennsylvania. And there is concern in the United States that some states haven't stockpiled enough anti-flu drugs.
President Obama said the flu may have run its course "like ordinary flus," however, the government is preparing for worst-case scenarios, such as the virus' potential reappearance this fall in more sinister form.
The Centers for Disease Control and Prevention said Friday the strain of flu is "a very unusual" four-way combination of human genes and genes from swine viruses found in North America, Asia and Europe.
CDC flu chief Dr. Nancy Cox said the good news is "we do not see the markers for virulence that were seen in the 1918 virus."
Still, U.S. authorities are pledging to eventually produce enough swine flu vaccine for everyone, but the shots won't begin until fall, at the earliest.
Scientists are racing to prepare the key ingredient to make a vaccine against the never-before-seen flu strain — if it's ultimately needed.
But it will take several months before the first pilot lots begin required human testing to ensure the vaccine is safe and effective.
"We think 600 million doses is achievable in a six-month time frame" from that fall start, Health and Human Services Assistant Secretary Craig Vanderwagen said.
"I don't want anybody to have false expectations. The science is challenging here," Vanderwagen told reporters. "It's a question of can we get the science worked on the specifics of this vaccine."
Researchers will get a better idea of how dangerous this virus is over the next week to 10 days, said Peter Palese, a leading flu researcher with Mount Sinai Medical School in New York.
So far in the United States, he said, the virus appears to look and behave like the garden-variety flus that strike every winter. "There is no real reason to believe this is a more serious strain," he said.
The Centers for Disease Control and Prevention have reported 141 cases of swine flu in 19 states. Some 430 of the nation's 130,000 public and private schools have closed, while high school, college and professional sporting events have been called off nationwide due to increasing fears.
On Friday, the World Health Organization, or WHO, raised its tally of confirmed human cases to 331, up from 257.
Cox, the CDC official, said the manufacture of a vaccine for the new virus would not interfere with the manufacture of a seasonal flu vaccine for the upcoming flu season. She said that, if it becomes necessary to make a supplemental swine flu vaccine, that vaccine would be prepared "in parallel" with the seasonal vaccine.
In a news conference Friday, the WHO said scientists believe the seasonal flu vaccine will not protect against swine flu. Although the seasonal vaccine has long-contained a version of the H1N1 flu virus, this is very different than the H1N1 swine flu virus researchers are now seeing, Marie-Paule Kieny, director of the WHO's initiative for vaccine research, told a news conference.
Because of this, world scientists are in agreement, for now, that the seasonal vaccine offers no protection, she said.
"We have no doubt making a successful vaccine is possible," Kieny said.
The reason why the vaccine will take so long to produce is because scientists must first isolate the virus and then adapt it to be made into a vaccine. It is believed that the adapted virus should be ready by the end of May. After this, the virus is injected into eggs where it will grow. From there, scientists will remove it, kill it and then formulate it into a vaccine.
After that, clinical trials in humans must be performed to ensure it's safety and effectiveness. Later, it will need to receive approval by national regulatory authorities, Kieny said.
The WHO is now reporting 11 countries have confirmed cases, including Germany, which confirmed Friday the first case of swine flu transmission within the country. This does not include Hong Kong and Denmark, which confirmed cases mid-morning Friday.
Although the CDC has tallied just 141 swine flu cases in the U.S., state health experts say the count is likely much higher. Among the U.S. cases confirmed by the Centers for Disease Control and Prevention are 51 in New York, 16 in Texas and 14 in California, as well as scattered cases in Kansas, Illinois, Connecticut, Florida, Massachusetts, Michigan, Arizona, Indiana, Nevada, Ohio, Maine and South Carolina.
State officials also confirmed cases in Minnesota, Georgia, Delaware, Utah, New Jersey, Virginia and Colorado.
Education Secretary Arne Duncan said Friday schools will continue to take their cues from public health officials as to whether to remain open or closed. He said schools with 1 or more confirmed cases, or schools where family members of students have tested positive for the flu are advised to close for up to 14 days.
He encouraged teachers to rework their lesson plans so that students can continue their studies at home and to continue to communicate with students by e-mail, online or the phone. Duncan also encouraged parents to make sure their children continue to focus on their studies while at home and for students themselves to make sure they don't fall behind their peers across the country whose schools are still in session.
Even though scientists say the new virus is more pig than human, the WHO said it plans to no longer call it "swine flu" to avoid confusion over the risk from pigs and eating pork. Health officials have stressed repeatedly that the disease is being transmitted human to human and that there is no risk from eating pork.
WHO spokesman Dick Thompson says the name change comes after the agriculture industry and the U.N. food agency expressed concerns that the term "swine flu" was misleading consumers and needlessly causing countries to order the slaughter of pigs.
He told reporters in Geneva "we're going to stick with the technical scientific name H1N1 influenza A."
Several countries have put a ban a pork imports. Hog futures fell for the sixth time in seven sessions on Thursday because of continued speculation that people will stop eating pork.
On Wednesday, the WHO boosted its alert level to one level below a full-fledged pandemic. The Phase 5 alert, indicating a pandemic could be imminent.
The U.S., the European Union and other countries have discouraged nonessential travel to Mexico. Some countries have urged their citizens to avoid the United States and Canada as well. Health officials said such bans would do little to stop the virus.
Where Did Virus Originate?
Medical detectives have not pinpointed where the outbreak began. Scientists believe that somewhere in the world, months or even a year ago, a pig virus jumped to a human and mutated, and has been spreading between humans ever since.
China has gone on a rhetorical offensive to squash any suggestion it's the source of the swine flu after some Mexican officials were quoted in media reports in the past week saying the virus came from Asia and the governor of Mexico's Veracruz state was quoted as saying the virus specifically came from China.
One of the deaths in Mexico directly attributed to swine flu was that of a Bangladeshi immigrant, said Mexico's chief epidemiologist Miguel Angel Lezana.
Lezana said the unnamed Bangladeshi had lived in Mexico for six months and was recently visited by a brother who arrived from Bangladesh or Pakistan and was reportedly ill. The brother has left Mexico and his whereabouts are unknown, Lezana said. He suggested the brother could have brought the virus from Pakistan or Bangladesh.
By March 9, the first symptoms were showing up in the Mexican state of Veracruz, where pig farming is a key industry in mountain hamlets and where small clinics provide the only health care.
The earliest confirmed case was there: a 5-year-old boy who was one of hundreds of people in the town of La Gloria whose flu symptoms left them struggling to breathe.
The Associated Press and Reuters contributed to this report.