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What’s a flu?
In spring 2008, the New Jersey legislature mandated that all children under 5 years of age in school, day care, or preschool receive an influenza vaccine every fall. The CDC/ACIP* recommended that an annual influenza vaccination be administered to all children under the age of 18 years . Some parents have expressed skepticism, cynicism, or fear about the vaccination program against influenza.
Here are the facts.
THE DISEASE is common; the yearly influenza epidemic causes millions of infections per year. Influenza is very contagious; it causes "disease among persons in any age group, but the rates of infection are highest among children". Influenza can be serious. Influenza causes 226,000 annual hospitalizations in America, many in children under 5 years. Influenza kills -on average 36,000 Americans, including more than 150 children in 2004, the majority previously healthy without any underlying medical condition or risk factor. Influenza is a common, contagious and bad disease; but it can be prevented. The vaccine works.
Influenza, or "flu", is a specific disease caused by one of several specific "Influenza A or Influenza B virus" that circulate in the Northeast USA every year from late fall through late winter. Sometimes confused with other viral diseases, influenza is usually more severe than the average cold, and often will include severe fatigue, muscle aches, and gastro-intestinal symptoms such as abdominal pain, nausea or vomiting. Both influenza A and B viruses are constantly undergoing minor changes-called "antigen drift". This antigen drift means each year a slightly different virus circulates; and, every year, everyone can be re-infected by either Influenza A or B (or both). If the current virus is similar to past flu viruses, a person will have varying amount of protection (immunity) from past infections, and that person will either not catch the current year flu or have a relatively mild form of the disease.
Some years, Influenza A undergoes a major change a.k.a. "antigenic shift". Unlike Influenza B which can spread only from human to human, Influenza A can infect not just humans but also horses, swine, chickens and ducks. Unfortunately while living in these animals, Influenza A can obtain entirely different antigens from the animal- specific influenza viruses that naturally infect ducks and chickens. This antigen exchange occurs particularly in the far east, where humans live in close contact with these animals. Whenever the flu virus has a major shift, the majority of people worldwide will have no protective immunity from past infections and are at great risk for a more serious infection and death. This is what happened in the great flu epidemic of 1918-19, and what experts fear could happen if the avian flu ever shares its antigen with Influenza A.
Influenza A and B are both transmitted from human to human via respiratory secretions, including air-born droplets from coughing. The influenza viruses in the secretions remain viable and infectious for many hours. During the annual epidemics, roughly half the people exposed to the virus become sick: typically 2-3 days after exposure. The illness begins abruptly with headache, malaise, achiness and fever. Over the next 72 hours, the flu will typically progress from a mild runny nose to convulsive fits of non-productive coughing. Photophobia (eyes hurting when exposed to light), extreme fatigue, loss of appetite and, in approximately 20% of the patients, gastrointestinal upset accompanies the respiratory symptoms. The symptoms fluctuate, being worse during the evening and night and when the fever rises. Severe symptoms usually peak at three to five days but the cough often lingers for a week or two. Symptoms of influenza are remarkably consistent from person to person and from year to year, enabling physicians to make a clinical diagnosis with reasonable certainty during the local epidemic.
There is NO EFFECTIVE CURE for influenza. The management is non-specific: rest, fluids and pain relievers. An historical aside and important warning: never use aspirin to treat influenza. Medical researchers discovered in the 1970s that aspirin use in influenza can trigger a serious, often fatal, condition called Reye Syndrome. Several anti-viral medicines can inhibit viral replication, giving one's immune system time to fight the virus. These medicines, if taken when exposed to influenza, can sometimes prevent the disease. If already infected, these medicines can have a modest effect, sometimes foreshorten the disease by one- two days, but only if taken early, within the first 48 hours of symptoms. The major problem with all the anti-viral medicines is the influenza virus are constantly mutating, and are becoming increasingly resistant.
PREVENTION is BEST. Vaccines prevent influenza disease more effectively than anti-viral medicines can. Effectiveness (i.e., prevention of illness in vaccinated populations) of influenza vaccines depend in part on the age and immunocompetence of the vaccine recipient (typically children respond better than the elderly), and the degree of similarity between the viruses in the vaccine and those in circulation (the more the antigen drift, the less the effectiveness). Obviously, the effectiveness also depends on the outcome being measured. When the measurement is lab- proven influenza illness, ER visits, hospitalizations and death, the protection is usually between 70-90%,(but closer to 60% when there has been large antigen drift). When the expectation is no winter illness, the effectiveness of the vaccine is erroneously underestimated. The flu vaccine will NOT protect against the many respiratory or intestinal illnesses (a.k.a. the common cold and GI bugs) caused by hundreds of other viruses that are not influenza viruses. Even with the flu vaccine, a typical child can still expect to catch on average 5 colds a winter.
INFLUENZA VACCINES can be either the old injectible shot: "TIV" (trivalent injectible vaccine) or the newer inhaled vaccine: "LAIV" (live, attenuated, inhaled vaccine). Both vaccines will work. They both can be life saving, especially for the elderly or anyone with weak hearts, asthma or other lung disease. The injectible has been used since 1940 , it is inactive (dead, killed with formaldehyde), and can not cause disease. The injectible is currently made by several manufacturers and come in two distinct formulations one meant for both children and adults and a second meant only for adults (the later contains thimersol- a mercury-containing preservative). While there has never been proof that thimersol ever caused autism, all children vaccines --including the injectible FLUZONE® and the inhaled FLUMIST®-- are now made without the mercury.
The major side effects of the injectible vaccine are local soreness in half of the recipients, usually lasting 1-2 days; diffuse body aches in 25% and fever in 10%; (interestingly in the largest study, 20% of the non-recipients also had diffuse body aches, and 8% fever). The injectible is approved for persons older than 6 months. The newer LAIV live-attenuated nasally inhaled vaccine, a.k.a. FLUMIST ® was approved in 2003 for persons between age 2 and 49years. The inhaled vaccine causes a runny nose in half of the recipients, usually less than 2 days; less than 10% of the recipient of inhaled vaccine complain of soreness or fever. Because it may exacerbate respiratory conditions, such as asthma, the inhaled vaccine is not to be given to people in high- risk groups. Lastly, neither vaccine should be given to persons with severe egg allergy without clearance from an allergist.
Following current CDC/ACIP RECOMMENDATIONS, we are recommending that annual vaccination be administered to all children under the age of 18 years, but especially:
Children with medical conditions are encouraged to schedule their vaccination as early as possible.
Children attending day care or pre-school in New Jersey are required to get vaccinated this season.
Children under the age of 9 who are receiving the vaccine for the 1st time or only received one dose last year will need 2 vaccines this season, one month apart.
Updated information on influenza can be found on the Internet at www.cdc.gov/flu/. Expert opinion on various topics in Infectious Disease, including influenza, can be found at www.isid.org.
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