The U.S. Food and Drug Administration’s approval of an H1N1 vaccine clears the way for a wide-scale immunization program. The first 45 million to 52 million doses are expected to be distributed by mid-October.

Human trials suggest a single 15 microgram dose will be enough to protect adults against the virus. That means those doses will cover more people than originally expected. Researchers initially thought most people would require two separate doses of as much as 30 micrograms each to produce immunity. Studies for the proper dosage in children are still underway.

Meanwhile, there is news from the transportation sector about measures to cut down on the spread of H1N1 and disease in general.

The Washington Metro Area Transit Authority has announced its using an “environmentally friendly disinfectant” to clean contact surfaces — such as fare boxes, seats, grab bars and poles — in its buses and trains to prevent the spread of influenza. Workers are doing this on a weekly basis. But transit officials say the cleanings may become more frequent if necessary. An estimated 1 million people ride D.C. Metro vehicles each day.

Meanwhile, two British companies — BAE Systems and Quest International UK — have announced new technology to inhibit the spread of H1N1 and other pathogens on board jetliners. Developers of AirManger say their filtration system eliminates virtually all airborne viruses and bacteria. For more on this device, see my On the Scene Blog.