Is a universal flu vaccine within reach? - The John Hopkins Newsletter - 10/16
Image of avian flu vaccine development by reverse genetics technique source: Wikimedia
The Basics of FluA flu virus is roughly round, but it can also be elongated or irregularly shaped. Inside are the genetic instructions for making new copies of the virus. Flu's most striking feature is a layer of spikes projecting from its surface. There are two different types of spikes: one which allows the virus to "stick" to a cell and initiate infection, the other is a protein which enables newly formed viruses to exit the host cell.
Virus A, B, C
Influenza viruses are classified as type A, B, or C based upon their protein composition. Type A viruses are found in many kinds of animals, including ducks, chickens, pigs, whales, and also in humans. The type B virus widely circulates in humans. Type C has been found in humans, pigs, and dogs and causes mild respiratory infections, but does not spark epidemics. Type A influenza is the most frightening of the three. It is believed responsible for the global outbreaks of 1918, 1957 and 1968.
Where Influenza Comes From
In nature, the flu virus is found in wild aquatic birds such as ducks and shore birds. It has persisted in these birds for millions of years and does not typically harm them. But the frequently mutating flu viruses can readily jump the species barrier from wild birds to domesticated ducks and then to chickens. From there, the next stop in the infectious chain is often pigs.
Pigs can be infected by both bird (avian) influenza and the form of influenza that infects humans. In a setting such as a farm where chickens, humans and pigs live in close proximity, pigs act as an influenza virus mixing bowl. If a pig is infected with avian and human flu simultaneously, the two types of virus may exchange genes. Such a mutated flu virus can sometimes spread from pigs to people.
In 1997, for the first time, scientists found that bird influenza skipped the pig step and infected humans directly. Alarmed health officials feared a worldwide epidemic (a pandemic). But, fortunately, the virus could not pass between people and thus did not spark an epidemic. Scientists speculate that chickens may now also have the receptor used by human-type viruses.
Tips to avoid catching the flu:
Cover your nose and mouth with a tissue when you cough or sneeze.
Throw the tissue in the trash after you use it.
Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
Avoid touching your eyes, nose or mouth. Germs spread this way.
Try to avoid close contact with sick people.
Stay home if you are sick until at least 24 hours after you no longer have a fever (100°F or 37.8°C) or signs of a fever (without the use of a fever-reducing medicine).
Follow public health advice regarding school closures, avoiding crowds and other social distancing measures.