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Background
Decreasing the Risk of Catching Pandemic Influenza by Increasing Social Distance
Background
Pandemic Influenza is overdue. When the pandemic occurs, vaccine will initially be unavailable or delayed. There are insufficient antivirals to use as protection against pandemic influenza for the general public. During an influenza pandemic, the main protection against influenza may be Social Distancing Groups who use Social Distancing Safe stores as personal decisions for individuals and their families.
At this time, the vaccine needed to protect against the pandemic strain will not be available for at least 6 months. When the vaccine becomes available, it will be distributed to priority groups over several months. Currently, the world population is 6 billion persons and the world’s capacity per year to produce annual influenza vaccine at the current formulation of 15 mg per dose is 900 million doses. Experts expect it will take 2-doses of the new strain vaccine to protect an individual. One vaccine manufacturer to date has produced a vaccine to protect against the H5N1 avian influenza strain. Clinical trials estimate two 90 mg vaccines one month apart would be required for protection. This decreases the world output of influenza vaccine to enough for 150 million people per year. Therefore the number of doses needed during a pandemic far exceed the world’s ability to manufacturer enough vaccine for the world’s population
Currently, several countries are stockpiling oseltamivir (Tamiflu) antivirals. The current worldwide demand for Tamiflu has created a two or more year backlog in shipment to countries. There is also no creditable evidence that Tamiflu would be effective against the H5N1 influenza strain.
Influenza is spread by droplets during face-to-face contact. There is also good evidence that influenza is spread through airborne spread, which means transmission could occur in enclosed spaces containing many people. Airborne spread may be reduced by avoiding enclosed spaces containing many people. Theoretically the use of medical masks, especially types like N95 masks, could help protect against influenza. There is some evidence that influenza may be spread by contaminated inanimate objects (fomites) which contaminate hands which then spread the infection to mucous membranes. This suggests that basic infection control measures, like proper hand washing could lessen the change of influenza transmission.
Incubation period is usually 1-3 days after contact with the virus. People infected with influenza are contagious or infectious 24-48 hours before symptoms appear and they are contagious after symptoms appear. Adults are contagious for 3-5 days after symptoms appear and children are contagious up to 7 days.
Since there are no adequate medical preventive measures, e.g. vaccine and antivirals, the infection control measures the general public choose may be critical to slowing the spread of influenza. Slowing the spread will spread the utilization of the medical care system for a longer time even if the same number of people became ill. In addition, slowing the spread may result in some people delaying contacting influenza long enough for them to be protected by vaccine and avoid pandemic influenza infection all together.
The most important measure patients with influenza can choose is to isolate themselves until 1 week (respiratory isolation) after they become ill with influenza. People who are not infected with influenza may need to choose to avoid all people who may be potentially infected (social distancing).
Social distancing (SD) may be the best chance for the general public to avoid the pandemic influenza infection until vaccine is available. Below, in order of potential effectiveness, are various aspects of SD:
Become part of a social distance group (SDG). A group may be as small as one person.
Avoid exposure within 3 feet of those outside your SDG.
Avoid enclosed spaces containing crowds, e.g., movie theatres, Wal-Mart, grocery stores, gas stations, schools, malls.
Use medical masks, like N95 masks, if you must get within 3 feet of anyone outside your SDG or if you must go into an enclosed space containing crowds. At this time there is no specific evidence that masks are effective, but they are not dangerous to use.
Wash hands after touching any item touched by someone outside your social distance group.
Social distancing will not be able to be done by many people. In addition, not every one who strictly applies its principles will avoid infection. But it should be able to protect some people. Since medical preventive measures such as vaccines and antivirals will not be available for at least months, one is faced with either no protective measures or trying something like this SDG concept.
Draft 12/14/05 by J. P. Lofgren, M.D.
Last Modified: June 20, 2006 09:10 PM