Preparing to Cope With a Pandemic Flu

A large-scale avian-flu computer-modeling project has recently been reported by the Los Alamos National Laboratory that predicts rapid vaccine development will be more effective than infection control in coping with a pandemic flu. The project, details of which are presented in the National Academy of Science Online, is based upon a “super-computer” model that uses actual data on current travel and work associations over a range of infectious disease parameters.

The information developed could be an important tool for planning community responses to cope with the potential of a flu pandemic because it would allow those responding to engage in a “what if” strategy session to determine the best disposition of always limited resources.  

Pandemic flu has two primary parameters that differentiate it from normal colds and influenza.  First, a pandemic flu is very communicable. Communicability refers to the potential of one person passing the flu to another person through casual contact. Not all diseases are communicable, and relatively few are spread by airborne means such as sneeze droplets. Evidence developed thus far indicates that the current avian flu spread by migratory birds is not communicable from human to human.  

The second characteristic of a pandemic flu is its lethality. Most colds and influenza do not pose a significant risk for healthy adults. Typically, flu will kill those who are not healthy to begin with as well as the very old, and infants. A pandemic flu, however, defeats the normal healthy human immune system and poses a very real risk not just to individuals but to large masses of people. The lethality of the current avian flu appears to be high not only in birds but also among poultry workers.  

Vaccines, Anti-Virals, and Isolation

Flu pandemics can be stopped or managed by two primary methods.  First, a vaccine can be given to non-exposed people to prepare their immune systems to fight the pandemic influenza. The problem here is that influenza is constantly shifting its genetic make-up.  This constant shifting is a challenge for vaccine makers if only because the vaccine for one strain of flu usually is not effective against other strains.

There is currently no vaccine against the avian flu. Other medications, called “anti-virals,” can be administered to treat an infection after it occurs. In general, though, these medications are much less effective than one administered before a person has been infected.  In the avian-flu cases detected and analyzed thus far, it appears that treatment with anti-viral medications is not very effective.

The second strategy is to prevent the exposure of people to the flu virus so that person-to-person spread is stopped before it starts. The cancellation of school classes, meetings, sporting events, and other gatherings is among the steps that can be employed. The wearing of masks is another safeguard that has been used effectively, most recently in the SARS epidemic of 2003.  

The quarantine of infected people is generally ineffective in fighting a pandemic flu because infection still will occur in some people who do not display obvious symptoms. They do not feel ill, and are not feverish, but are nonetheless capable of spreading the disease.  

The Los Alamos model will allow variable communicability and what-if lethality parameters to be tested against the known patterns of U.S. population movements to replicate a variety of scenarios. The use of masks and cancellation of events can be tested, for example, against the use of vaccines and medications. In the Los Alamos Model, the rapid development of vaccination seems to be the most effective way to fight the avian flu.

Because EMS (emergency medical services) providers and the nation’s medical systems probably will be the first community-response assets to be exposed, a credible case can be made that vaccine priority should be given to EMS hospital personnel.