Nasal Swabs to Diagnose Flu Are Unscientific and Meaningless
During outbreaks of influenza, including the past H1N1 epidemic, it is the Standard of Care for doctors to perform a nasal swab to diagnose the flu. A swab, similar to an everyday cotton swab, is inserted into the nasal cavity for a sample and sent to a laboratory. If the swab comes back positive, then the illness is determined to be influenza and an antiviral medication is often prescribed. The problem with this procedure is that it is absolutely meaningless and has no scientific basis whatsoever in determining if the illness in question really is due to the flu. This is due to several different factors.
Questionable Accuracy
Nasal flu swabs require a degree of skill from the sample collector and quite a bit of cooperation from the ill person to allow a swab to be inserted high into the nasal cavity. This is an uncomfortable procedure at best and even those given thorough instructions will reflexively pull away and reduce the chance of obtaining a proper sample, making the accuracy of the test very suspect. Even the CDC admits that nasal swabs are not highly worthwhile for diagnosing H1N1 infections. Most doctors know this and will often prescribe antiviral medications even when the swab is negative because a patient’s symptoms match the flu to a degree that there is still a high level of suspicion. However, if a doctor is going to give a medication regardless of the outcome of the swab, there is just no justification for collecting and spending money on an uncomfortable test with poor accuracy.
Exposure vs Illness
Even if a swab is positive, it can only determine exposure to the flu; it can in no way determine if the current illness is caused by the flu. Because the nasal passages are not sterile and are exposed to billions of microorganisms every day, the simple presence of a disease-causing organism in the nasal passages in no way implies that the current illness is due to a microorganism present, or even that the person has ever even had that disease in the past. It simply means that the person has been exposed to the organism. A telling example of this is that nasal swabs for the ‘superbug’ Methicillin Resistant Staph Aureus (MRSA) are done on a routine basis for a large percentage of hospitalized patients, yet this swab is NEVER used to determine if the patient’s illness is from MRSA; further testing is always required to determine the cause of illness regardless of the findings from the nasal swab. In this context it is used only to find out if they are colonized with MRSA in order to prevent potential exposure to hospital patients with immune dysfunction.
Lack of Studies
When medical tests are developed, volunteers are used to determine what is ‘normal’ in healthy people, but testing groups of healthy people has never been done to determine if healthy people carry the flu virus in their nasal passages from casual exposures or past illnesses. Because no studies with a ‘control’ group have ever been done, doctors using this test are simply ‘presuming’ that the presence of the virus indicates that their illness is due to that virus. But it is absolutely possible that harboring the flu virus in the nasal passages is completely normal in a large percentage of the population. These facts together make using nasal swabs for the flu an absolutely worthless and unscientific diagnostic test that the medical community spends millions of health care dollars on every year.
