MONDAY, Jan. 28 (HealthDay News) -- A drop of vaccine placed under the tongue might one day ward off the flu.

Not only would the new method, so far tested only in mice, be more convenient, it also appears to be more effective than the flu shot or nasal spray, the South Korean researchers noted.

"This has the potential to be widely accepted by people who are afraid of needles, but it's clearly an introductory study and needs to be further studied in humans," said Dr. William Reisacher, an assistant professor of otolaryngology at Weill Cornell Medical College in New York City.

And in developing countries, there is another advantage: indirect prevention of other diseases.

"Sublingual [under the tongue] vaccination elicits broad spectrums of systemic and mucosal immunity. This route is needle-free so that developing countries' people would most benefit to avoid contamination/infection by reused needles," said study senior author Mi-Na Kweon, chief of the Mucosal Immunology Section at the International Vaccine Institute in Seoul.

And according to Kweon, whose study was in this week's issue of the Proceedings of the National Academy of Sciences, "several clinical trials using sublingual route are now ongoing so that it might be not so far away for humans."

Most flu vaccines are delivered via injection, though recently a nasal spray (FluMist) has become available. The flu shot, which contains killed virus, is approved for use in people older than 6 months. The nasal spray is made with live but weakened flu viruses, and is approved for healthy people aged 2 to 49 who are not pregnant.

According to background information in the study, most environmental pathogens, such as the flu virus, enter the body through the respiratory, gastrointestinal and genital tracts.

The sublingual vaccine would provide protection at the point of entry, so to speak. And unlike other oral vaccines, it would avoid subjecting the vaccine to enzymes and acids in the stomach.

Sublingual therapy is already used for allergy drugs in children, primarily in Europe.

In this study, mice were given two doses of either live or inactivated flu virus two weeks apart. Both delivery methods were effective in stimulating the immune system.

When later exposed to a severe form of influenza virus, the animals were fully protected.

Delivering vaccine under the tongue also prevented viruses from traveling to the central nervous system, which is a rare but dangerous complication of the nasal spray.

"They basically showed that the vaccine was able to affect change in the immune system and protected against the flu," Reisacher said. "It's an effective way of exposing a vaccine to the immune system. With sublingual delivery, the vaccine is not absorbed that rapidly but it is maintained in the lining of the mouth -- the mucosa -- allowing the antigen to be exposed [to the immune system]."

More information

For more on current flu vaccines, visit the U.S. Centers for Disease Control and Prevention.

MONDAY, Jan. 21 (HealthDay News) -- Current and former smokers with the lung disease idiopathic pulmonary fibrosis (IPF) have a worse prognosis than nonsmokers, says a British study.

IPF is untreatable, and patients usually die within five years of diagnosis. Previous research had suggested that current smokers with IPF may live longer than former smokers, but the authors of this new study said that was likely due to a "healthy smoker effect."

"Smoking is associated with a higher degree of mortality in IPF, and an earlier finding, suggesting the contrary, was almost certainly due to the fact that smokers tend to stop smoking when disease becomes more severe -- and so current smoking is linked to milder disease," research leader Dr. Athol U. Wells, of the Interstitial Lung Disease Unit at the Royal Brompton Hospital in London, said in a prepared statement.

Publishing in the second issue for January of the American Journal of Respiratory and Critical Care Medicine, Wells and his colleagues analyzed the medical records of 249 IPF patients and found nonsmokers survived longer than current or former smokers.

"We speculate as to whether this reflects disease co-morbidity -- that is, excess mortality from non-pulmonary disease ascribable to smoking -- or an effect of smoking in driving progression of lung disease," Wells said.

The team is doing further research in this area.

"The next step is to pursue the idea that mechanisms linked to smoking cause progression of pulmonary fibrosis. If we can then understand these mechanisms better, this may give us new treatment options," Wells said.

More information

The U.S. National Heart, Lung, and Blood Institute has more about idiopathic pulmonary fibrosis.

WEDNESDAY, Dec. 12 (HealthDay News) -- Infants delivered by elective Caesarean section are up to four times more likely to have breathing problems than babies born vaginally or by emergency C-section, says a Danish study published in the Dec. 12 online issue of the British Medical Journal.

Researchers analyzed data on 34,000 births and found the 2,687 infants delivered by elective Caesarean section had a nearly fourfold increased risk of breathing problems if they were delivered at 37 weeks' gestation, a threefold increased risk at 38 weeks' gestation, and twice the risk at 39 weeks' gestation.

For example, 2.8 percent of infants delivered by intended vaginal delivery (which includes both vaginal delivery and emergency Caesarean) at 37 weeks gestation had general respiratory problems, compared with 10 percent of infants delivered by elective Caesarean section.

At 38 weeks, the rates were 1.7 percent versus 5.1 percent, and at 39 weeks, 1.1 percent versus 2.1 percent.

The reasons why elective Caesarean increases the risk of respiratory problems aren't clear. The study authors suggested that certain hormonal and physiological changes associated with labor are necessary for an infant's lungs to mature. These changes may not occur in infants delivered by elective Caesarean section.

Postponing elective Caesarean section until 39 weeks gestation may greatly reduce the risk of breathing problems in infants, the researchers noted.

More information

The Nemours Foundation has more about Caesarean section  .