Defense has vested interest in tracking flu

In April, officials at an Air Force laboratory in San Antonio and a Navy lab in San Diego discovered something unexpected. Throat cultures taken from three sick patients, family members of active-duty military personnel in Texas and California, tested positive for a new virus similar to a type of influenza that occurs in pigs. The labs, part of the Defense Department's vast network of facilities on constant lookout for infectious disease, discovered the first three North American cases of what initially was called swine flu.

"If it wasn't for the [Defense Department's] surveillance system it would have been much later before we realized novel H1N1 [virus] even existed," says Army Lt. Col. Wayne Hachey, director of preventive medicine and surveillance at the Office of the Assistant Secretary of Defense for Health Affairs.

The military has a vested interest in tracking infectious disease, the result of hard lessons learned nearly a century ago, when illness proved as potent on the battlefield as howitzers and chemical weapons. Half the U.S. troops who died in World War I were felled by the 1918 influenza virus that swept the world. "We look out for this all the time, whether it be influenza or other infectious disease, because these things can be showstoppers," Hachey says.

The 2009 H1N1 virus, which first emerged in Mexico last spring, shows no signs of having anything like the virulence of the 1918 strain. And it isn't behaving like seasonal flu, which poses the gravest danger to infants, the elderly and those with weakened immune systems. In this case, children and young adults appear most vulnerable. For the military services, where the bulk of combat troops are between the ages of 18 and 24, that's a huge concern. So when the vaccine for H1N1 flu becomes available, likely in October, U.S. troops are among those who will receive it first.

"If all goes well, we would expect to start vaccinating sometime in October," says Hachey. Defense is purchasing 2.7 million doses of vaccine through the Health and Human Services Department, which has the lead in responding to flu. Health officials predict individuals will need only one shot of vaccine to be protected against the virus, but that could change as the virus evolves.

While Defense expects to have enough vaccine eventually to immunize all service members, those first in line for the shots will be deployed troops, new recruits in training, sailors aboard ships and personnel with critical roles in vital operations. "Any place where we take people and cluster them pretty tightly and put them under stressful conditions, those are the people we want to protect first" because they are subject to the highest rates of transmission, Hachey says.

The President's Council of Advisors on Science and Technology reported in August that a "plausible" scenario for the expected resurgence of H1N1 virus was that anywhere from 30 percent to half the U.S. population could become infected this fall and winter, leading to 1.8 million hospital admissions and between 30,000 and 90,000 deaths. To put the predicted death rate in context, every year 30,000 to 40,000 Americans die of seasonal flu or its related complications.

To cut down on transmission rates, the military services screen troops before they deploy overseas, and when they arrive in theater. When several dozen troops on their way to Iraq showed flulike symptoms this summer, they were quarantined in Kuwait where they were treated with antiviral drugs and monitored until they were deemed free of the virus before being allowed into Iraq.

"We have public health guidelines for both large and small units to decrease the chances of transmission," Hachey says. One recommendation for small units operating in remote locations for extended periods is that they carry antiviral medications, so at the first sign of illness the entire unit can begin treatment before individuals fall ill.

"In 1918, half of the [influenza] deaths resulted from bacterial infections after people got the flu. We stockpile antibiotics to counter that possibility," Hachey says. The department has 8 million antiviral treatment courses on hand for such a possibility, he adds.

At a media briefing in early September, Thomas Frieden, director of the Centers for Disease Control and Prevention, said, "So far, everything that we've seen, both in this country and abroad, shows that the virus has not changed to become more deadly. That means that although it may affect lots of people, most people will not be severely ill." But Frieden also noted that H1N1 influenza is unpredictable, which means health officials must be prepared to change their approach as the virus evolves.

The council's report noted that the 1918 pandemic began with a relatively mild wave of illness in the spring, followed by much more severe second and third waves during the following year.

"This pattern could conceivably be repeated with the 2009 H1N1 virus," the report stated.

If the virus were to follow a similar pattern, something "highly unlikely" in the council's view, it could spawn a national crisis. In recent years, the government has spent a great deal of time, money and energy developing a national response framework and detailed planning documents for just such an event. But as the council also noted, "These systems have never been tested by an event of the scope and scale described here."