Adults can best protect themselves against the regular seasonal flu by getting shots instead of a nasal spray; that's the finding of a new study just published in the New England Journal of Medicine.

"They both prevent influenza but, in our studies, in healthy adults, the injected vaccine worked better than the nasal spray vaccine," said Dr. Arnold Monto.

The University of Michigan study found nasal spray was about half as effective as the shots for adults: 68-percent effectiveness for the shot; 36-percent effectiveness for the nasal spray.

But in children"the nasal spray vaccine may actually work better than the injected," said Monto.

Nasal spray maker Medimmune says other studies have shown its product to be just as effective for adults and children.

"So in adults, really, the jury's still out. In children, however, we've consistently seen that flu mist recipients, or children receiving flu mist, get less influenza than those receiving the flu shot," said Dr. Ambrose with Medimmune.

The Michigan study, done during the flu season two years ago, suggests adults might not get the same kind of protection from live-virus nasal sprays because they've been exposed to different flu strains before. Because most young children have not been exposed, their immune systems have a stronger response.

Because the H1N1 flu virus is completely new to all age groups, the director of this study believes adults and children could be protected by either a shot or a nasal spray!

"I would take the one that's available first," said Monto.

That's encouraging news, with the first H1N1 vaccines just weeks away. In all, the U.S. government has ordered more than 250 million doses of H1N1 vaccine.