Hand Sanitizer - Effectiveness

Effectiveness

The Centers for Disease Control says the most important way to prevent the transmission of dangerous diseases is to frequently wash your hands with soap and water and/or use a hand sanitizer. If soap and water are not available it is recommended to use a hand sanitizer that contains at least 60 percent alcohol or contains a "persistent antiseptic". Alcohol rubs kill many different kinds of bacteria, including antibiotic resistant bacteria and TB bacteria. It also has high viricidal activity against many different kinds of viruses, including enveloped viruses such as the flu virus, the common cold virus, and HIV, though is notably ineffective against the rabies virus. Alcohol rub sanitizers are not very effective against Norovirus (winter vomiting virus) unless they are combined with benzalkonium chloride in a hand sanitizer. Alcohol rubs also kill fungi. University of Virginia Medical School researchers concluded that hand sanitizing is more effective against fighting the common cold than hand washing.

Alcohol kills both pathogenic (disease causing) microorganisms as well as resident bacterial flora, which generally do not cause illness. Research shows that alcohol hand sanitizers do not pose any risk by eliminating "good" microorganisms that are naturally present on the skin. The body quickly replenishes the good microbes on the hands, often moving them in from just up the arms where there are fewer harmful microorganisms. However, alcohol also strips the skin of the outer layer of oil, which may have negative effects on barrier function of the skin. A study also shows that disinfecting hands with an antimicrobial detergent results in a greater barrier disruption of skin compared to alcohol solutions, suggesting an increased loss of skin lipids.

Alcohol rubs are approximately 100 times more effective against viruses than any form of hand washing. Isopropyl alcohol will kill 99.99 percent or more of all non-spore forming bacteria in less than 30 seconds, both in the laboratory and on human skin. A controlled study of 200 workers at FedEx in 2004 showed that placing hand sanitizer dispensers in an office and educating workers about their use resulted in a 21% reduction in absenteeism. Controlled studies showed an even greater reduction in absenteeism (51%) in elementary schools and college dormitories (43%).

The alcohol in hand sanitizers may not have the 10–15 seconds exposure time required to denature proteins and lyse cells in too low quantities (0.3 mL) or concentrations (below 60%). Mackintosh (1984) found that application of 0.3 milliliters alcohol rub to the hands was no more effective than plain soap-and-water hand washing, but that increasing the volume to 0.5 milliliters increased the effectiveness of alcohols substantially. In environments with high lipids or protein waste (such as food processing), the use of alcohol hand rubs alone may not be sufficient to ensure proper hand hygiene).

For health care settings like hospitals and clinics, optimum alcohol concentration to kill bacteria is 70% to 95%. Products with alcohol concentrations as low as 40% are available in American stores, according to researchers at East Tennessee State University.

Not all forms of bacterial pathogens are equally susceptible. Certain spores of endospore forming bacteria, especially the endospores of gram-positive bacteria (e.g. Clostridium difficile) are relatively resistant to sanitizers and soap and water and remain biologically viable after their use. During the 2001 anthrax attacks on the United States Postal Service, authorities warned that alcohol hand rubs and soap and water would not kill anthrax endospores but they will kill the anthrax bacteria.

Some medical opinions question the effectiveness of alcohol-based hand sanitizers for preventing influenza. Arthur Reingold, vaccine specialist who has advised for the WHO, worries that "in the determination to tell people what they can do to protect themselves, people pooh-pooh things like masks, which really are effective against influenza, and are reluctant to get vaccinated." He claims that "washing hands really is wonderful for preventing many diseases, such as the common cold, but it's not very helpful to prevent influenza, studies done 40 and 50 years ago pretty much show it's impossible to get influenza through hand-to-hand contact". Instead, he says that "you must breathe the virus into your lungs". In the same lay press article, Bonnie Henry, Director of Public Health Emergency Management at the B.C. Centre for Disease Control, agrees with Reingold that the principal way to get swine flu is by breathing the virus right into your lungs. However, she says animal studies have shown that the virus can infect you through your nose, your throat, and even through the tear ducts of your eyes. For example, research into the transmission of influenza from swine to humans has shown a statistically significant reduction in transmission if the handler wears gloves when working with sick animals, therefore implying that there is a distinct danger of catching the influenza virus via hand-to-face transmission. That opinion is shared by US Public Health, CDC and WHO officials, who therefore agree that washing the hands with soap and water or the use of a hand sanitizer (and not touching eyes, nose or mouth) are important measures to help prevent the spread of influenza.

Peter Palese, a professor of medicine and infectious diseases at the Mount Sinai School of Medicine in New York City, has said that hand washing isn't all that helpful against the flu because the flu isn't like other respiratory diseases. "The flu virus isn't very stable on the hand," he said. "The virus has a lipid membrane that flattens out when it's on your hand, and it gets inactivated." However Mark Nicas, an adjunct professor at the University of California-Berkeley School of Public Health, maintains that a significant number of flu cases are indeed spread by hands touching one another, and then touching your eyes, nose or mouth. "I think that hand contact accounts for maybe one-third of influenza infections," he says. Furthermore, whereas the influenza virus can survive for only minutes on a person's hands, researchers have found that it can survive for hours (some say even days) on many other surfaces. The University of Minnesota Center for Infectious Disease Research and Policy (CIDRAP) produced a document which says: "Studies have shown that influenza viruses can survive on environmental surfaces and can infect a person for up to 2 to 8 hours after being deposited on an environmental surface" if the person touches that surface and then touches his or her eyes, nose or mouth.

Research by Ronald Turner found that there was no statistically significant advantage to using hand sanitizers to prevent the flu or rhinovirus infection.

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