In an early-morning announcement today, researchers reported that an experimental HIV (human immunodeficiency virus) vaccine effectively reduced the number of people who contracted the virus by nearly a third.

Tested in a U.S.-sponsored trial that involved more than 16,000 volunteers in Thailand, the vaccine was administered in six injected doses starting in 2006 to half of the group, and the other half received a placebo. Seventy-four people in the placebo group had contracted HIV by the end of the trial, whereas only 51 of the vaccinated group tested positive.* The injections consisted of two vaccines that had proven unsuccessful on their own: Sanofi-Aventis SA's ALVAC and VaxGen Inc.'s AIDSVAX.

The results came as a surprise to HIV-vaccine skeptics in the AIDS (acquired immunodeficiency syndrome) research field, whose numbers have increased after years of failed vaccine trials. "It's safe to say that the scientific community is caught off-guard," Mitchell Warren, director of the AIDS Vaccine Advocacy Coalition, told Bloomberg News. Before the announcement, Marie-Paule Kieny, director of the World Health Organization's Initiative for Vaccine Research, told the news service: "I don't think that there is a lot of expectation that the efficacy of this vaccine will be very high." A 2007 clinical trial of a vaccine made by Merck was stopped when researchers found that, in fact, more people who received the active vaccine (49) than the placebo (33) had contracted HIV.

The U.S. Food and Drug Administration approved the long-awaited vaccines for the H1N1 "swine" flu virus this afternoon. It is expected to be available in a month at about 90,000 locations nationwide, the Associated Press reported. 

"We will have enough vaccine available for everyone," Kathleen Sebelius, Health and Human Services Secretary, said in an address to Congress today, the AP reports. The government, which does not expect everyone to get the vaccine, has an order out for 195 million doses, but only about 45 million are expected to be available by mid-October. The announcement from the National Institutes of Health (NIH) last week that one dose is sufficient to protect against the virus means supplies will be more robust than they might otherwise have been. Nevertheless, the government is prepared to order more if necessary.

Here is who should be first in line this fall when the H1N1 vaccine becomes available, the U.S. Centers for Disease Control announced today: Pregnant women, all children (except those under six months old), teens and young adults up to 24 years old, people with babies under six months old, health care workers and nonelderly adults who have underlying medical conditions.

“We really should go out full force to make sure these groups get addressed,” Anne Schuchat, the CDC National Center for Immunization and Respiratory Disease director, said at a press conference in Atlanta, Ga.

The entire group, estimated to sum up to just under 149 million people, will be the primary targets for the first rounds of vaccine but in no particular order. Only in rare situations of shortages, Schuchat noted, would certain sectors within that larger group be prioritized (bringing the total number of the core down to about 41 million).

The first vaccines against H1N1 in humans will be put to the test starting tomorrow. The Australia-based pharmaceutical company CSL, Ltd., will commence the trials in Adelaide by giving 240 healthy volunteers the shot, Bloomberg News reported today.

“The world will be watching to see the immunogenicity results of this first clinical trial,” the World Health Organization (WHO) director of vaccine research told Bloomberg. The crucial result she refers to is exactly how much antigen it will take to fend off the virus. And that amount, the report notes, will provide more concrete data about how many doses companies will be able to make this year. The WHO has recommended that when a vaccine does become available, healthcare workers be the first in line to receive it.

As the World Health Organization (WHO) today acknowledged the spreading swine influenza virus by moving the pandemic threat awareness level up one notch to 5, the U.S. Centers for Disease Control (CDC) worked to get drug companies the materials they need to create a vaccine. Meanwhile, the U.S. Department of Health and Human Services (HHS) said it is unlikely that any new swine flu vaccine would be included in the batches of seasonal influenza vaccines already in production for the typical August vaccine ship date.

CDC and others are working to create the virus reference strain by the end of May that drug companies need to make a vaccine, says Bruce Gellin, director of HHS's National Vaccine Program Office and the agency's deputy assistant secretary for health. Once these companies make the necessary adjustments to their facilities and processes (which usually takes two or more weeks), he adds, they begin developing a pilot vaccine that the National Institutes of Health (NIH) tests to determine the amount of antigen per dose and number of doses, as well as information on safety.

With swine flu infections now being reported in six different countries, and concern mounting for even more, researchers are looking for ways to keep the outbreak in check. Influenza's unpredictability has stymied efforts to create a universal vaccine that could be mass-produced in advance of a pandemic threat and used to treat a variety of different virus strains.

Instead, drug companies annually try to predict which strains are most likely to circulate and then make enough of a particular flu vaccine to address those strains. Unfortunately, the wrong type of influenza vaccination provides little protection: for example, vaccination with seasonal influenza vaccine containing human influenza A (H1N1) would not be expected to provide protection against swine influenza A (H1N1) viruses, according to the U.S. Centers for Disease Control. The H and N refer to viral proteins, hemagluttinin and neuraminidase, that help the virus infect cells and reproduce within a host. Even viruses that share the same major subtypes—in this case, the H1 and N1—can have subtler differences and a vaccine against one might not generate antibodies that are effective against the other.

Minnesota health officials are reporting an unusual death linked to a strain of polio once used in vaccines.

The Minnesota Department of Health said yesterday that a man, whom they did not identify, with symptoms of the paralyzing disease died last month. The officials said that he was infected with a strain of polio used in an oral, live-virus polio vaccine that was discontinued in the U.S. in 2000, suggesting that he caught the infection from someone who had received the live vaccine before it was pulled from the market. Polio vaccines used in the U.S. today are injected and contain only inactivated virus, though live-virus vaccines are still used in some developing countries, according to the Centers for Disease Control and Prevention (CDC).

The number of cases of polio last year climbed – and spread into countries where it was previously wiped out — despite an aggressive worldwide effort to eradicate the potentially paralyzing virus in the nations still battling it half a century after the introduction of the polio vaccine.

An estimated 350,000 cases of the disease occurred annually in 1988, when world leaders launched the Global Polio Eradication Initiative to eliminate the virus in the 125-plus countries where it still existed. By 2006, polio remained endemic to just four countries – Nigeria, Afghanistan, India and Pakistan – and by 2007, the number of reported cases was down to 1,315. But over the next year, infections rose by 26 percent, to 1,655 cases, according to the Morbidity and Mortality Weekly Report (MMWR).

Cytomegalovirus (CMV), a form of herpes, is the most commonly transmitted infection between pregnant women and their babies, affecting 30,000 U.S. newborns a year and leaving some 8,000 of them with permanent damage ranging from mental retardation to vision and hearing loss. Scientists have had a tough time trying to come up with a vaccine against the virus, which is harmless in healthy adults, though it can cause eye inflammation and changes in blood cell count and the gastrointestinal tract in people with AIDS or other immune system conditions.

But one experimental vaccine is showing promise in preventing women from becoming infected with CMV. (As Scientific American noted in its January issue, CMV vaccines are also being tested in brain tumor patients, because many of the malignancies are found to contain the virus.)

Could the common cold become a thing of the past? Scientists have unraveled the genetic code for all 99 strains of the rhinovirus, but there may be a disconnect between excitement over the feat in the lab versus at pharmaceutical companies that would ordinarily develop a cure or vaccine against infection.

The discovery, published this week in Science, means that, in theory, drug or vaccine developers have a map of possible targets against the cold virus. "There is real promise now, based on full understanding of this virus, that we have never had before," study co-author Stephen Liggett, a professor of medicine at the University of Maryland School of Medicine, told the Baltimore Sun. "Let's get, perhaps, a single pill [that] will kill the virus that day, that moment, and within six hours you are cured. It is possible."