Swine Flu

Is it possible to prevent swine flu if the swine flu vaccine (or other flu strain vaccines) is not readily available?

Although vaccination is the best way to prevent the swine flu, there may be times in the future when the swine flu vaccine may not be available. There are no shortages of the trivalent flu vaccine that contains H1N1 antigens. However, during the 2009 H1N1 pandemic, this situation did occur so people wanted to know what they could do to protect themselves. If, in the future, vaccine supplies do not meet demands, there are some things people can do to try and prevent infection. Without vaccination, the best strategy is to not allow any virus type to contact a person’s mucus. Quarantining any virus-infected people is an extreme measure that may work in some instances (for example, China used this method), but even with quarantining, the virus may still spread by people who have minimal or no symptoms.

The next step, that is easier to be implemented by individuals, is for people with the disease to self-quarantine until they become noninfectious (about seven to 10 days after flu symptoms abate). Infected people can wear surgical masks to reduce the amount of droplet spray from coughs and sneezes and throw away contaminated tissues. Unfortunately, these approaches depend on the compliance of many other people, and the likelihood that such methods will be highly successful in preventing flu virus infections, at best, is only fair. Such methods did not stop the 2009 H1N1 pandemic, although they may have some benefit for a few individuals.

Yet there are still some other methods available to individuals. Perhaps the best way for individuals to try to prevent flu virus infection is a combination of methods that are aimed at fulfilling the very basic principle that if the virus doesn’t reach an individual’s mucus membrane cells, infection will be prevented. The methods are as follows:

1. Kill or inactivate the virus before it reaches a human cell by using soap and water to clean your hands; washing clothing and taking a shower will do the same for the rest of your body.
2. Use an alcohol-based hand sanitizer if soap and water are not readily available, and use sanitizers on objects that many people may touch (for example, doorknobs, computer keyboards, handrails, phones), although some researchers suggest that such sanitizers are generally ineffective.
3. Do not touch your mouth, eyes, nose, unless you first do items 1 or 2 above.
4. Avoid crowds, parties, and especially people who are coughing and sneezing (most virus-containing droplets do not travel more than 4 feet, so experts suggest 6 feet away is a good distance to stay). If you cannot avoid crowds (or parties), try to remain aware of people around you and use the 6-foot rule with anyone coughing or sneezing. Do not reach for or eat snacks out of canisters or other containers at parties.
5. Avoid touching anything within about 6 feet of an uncovered cough/sneeze, because the droplets that contain virus fall and land on anything usually within that range.
6. Studies show that individuals who wear surgical or N95 particle masks may prevent inhalation of some H1N1 virus, but the masks may prevent only about 50% of airborne exposures and offer no protection against surface droplets. However, masks on H1N1 infected people can markedly reduce the spread of infected droplets.

These six steps can help prevent individuals from getting H1N1 and other types of infection, but for many people, adherence to them may be difficult at best. However, there are some additional strategies that may also help prevent viral infections in unvaccinated people according to some investigators. Saline nasal washes and gargling with saline (or a commercial product) as a way to reduce or eliminate viral virus from mucus membranes has been suggested. Proponents of these methods base their rationale on the fact that flu viruses usually take about two to three days to proliferate in nasal/throat cells. While nasal washes and gargling may be soothing to some people, there are no studies that indicate H1N1 or other viruses are killed, inactivated, or completely removed by these methods; conversely, there are no data suggesting these methods cannot have any effect on H1N1. However, with long-term nasal washes using Neti pots, sinus infection with other pathogens may be encouraged.

Other investigators and physicians have offered additional methods that may help reduce exposure to H1N1 virus. For example, Dr. Gerberding, a former CDC director, had several suggestions about how to avoid H1N1 infection on an airplane. She suggested the following:

1. If a person is next to you or near (within 6 feet) and is coughing/sneezing, ask the flight attendant to offer the person a mask.
2. If there are available seats 6 feet or more away from the coughing/sneezing person, ask to change your seat (planes are good means of travel because the air is recirculated through HEPA filters that can capture viruses, but even the filters will not help if people touch areas where droplets have landed; HEPA filters are usually not available in buses, cars, ships, or trains).
3. Turn away from the coughing/sneezing person and turn the air vent toward the person to blow the droplets away from yourself.

Variations of her suggestions may be applicable in many different social or work, or travel situations, but there are no data to prove these methods are effective. In addition, common-sense precautions such as not drinking or eating things touched by others, avoiding casual physical contacts (for example, handshakes, social hugs or kisses, public water fountains [these are OK if you touch nothing and lips only touch flowing water], banisters on stairways, and restroom door handles) will limit exposure to H1N1 and other viruses. Again, these common-sense suggestions lack data substantiation.

Many investigators suggest that people stay well hydrated, take vitamins, and get plenty of rest, but these precautions will not prevent H1N1 or other viral infections, although they may help reduce the effects of infection by strengthening the person’s immune system to fight infection. Similarly, current antiviral medications (described in the preceding section) act on H1N1 and other viruses that have already infected cells; they work by preventing or reducing viral particles from aggregating and being released from infected cells. Timing is important; if only a few cells are infected and the antiviral medications are administered quickly (usually before flu symptoms develop or within 48 hours), the viruses are reduced in number (they cannot easily bud out from the cell surface), so few, if any, other respiratory or mucus membrane cells become infected. This can result in either no flu symptoms or, if a larger number of cells were initially infected, less severe symptoms. The overall effect for the person is that the H1N1 or other viral infection was prevented (it was not; the symptoms were prevented from developing) or that symptoms were reduced.

In the strictest sense of the word prevention, even effective vaccines do not “prevent” infections. What they do accomplish is to alert the immune system to be on guard for certain antigens that are associated with a specific disease-causing agent (for example, H1N1 virus, pneumococcal bacteria). When the agent first infects the host, its antigens are recognized, and these cause a rapid immune response to occur that prevents the pathogen from spreading and developing symptoms in the host. People, including physicians and researchers, often term this complex response to vaccination as “prevention of infection,” but what actually occurs is the prevention of further infection so well that symptoms do not develop or are minimal in the host.

In summary, if H1N1 or other viruses fail to contact cells they can infect, the disease will be prevented. As stated above, this is difficult, but not impossible, to do in almost all societies. Prevention of flu symptoms of infection is possible with antiviral medications if these are given very early in the infection. There are many other methods that may reduce the chance of getting the virus on a person’s mucosal surface, but most methods have not been backed up with objective data. Most doctors and investigators suggest that items that help boost or allow the immune response to function well will help people resist H1N1 and other viral infections and reduce symptoms, but these also do not prevent infections. Consequently, while waiting for a specific antiviral vaccine to be developed or become available, there are some ways individuals can improve their chances of preventing or reducing the symptoms of flu virus infections. All of these suggestions apply to H3N2v-caused swine flu as well. Because H3N2v flu has been more closely related to pigs, pig farming and county fairs, people who are at higher risk (see above) should avoid contacting pigs in these settings.