June 27, 2018
Stay Flu-free this winter
Can you really catch the flu from touching banknotes, light switches and other surfaces? Does the flu vaccine give you the flu? We enlist the help of Doctor Jim Finn, Australian Medical Association Queensland vice president, to debunk some of the myths surrounding the flu and vaccines.
What is the flu?
Influenza, commonly known as “the flu”, is an infectious disease caused by an influenza virus. Symptoms can be mild to severe and include a high fever, runny nose, sore throat, muscle pains, headache, coughing, and feeling tired. These symptoms typically begin two days after exposure to the virus and most last less than a week. The cough, however, may last for more than two weeks. In children, there may be nausea and vomiting, but these are not common in adults.
If you think that you have the flu what should you do?
You should see your general practitioner for diagnostic testing and have time off from work both to recover and to avoid infecting work contacts.
How can you avoid getting the flu?
Usually, the virus is spread through the air from coughs or sneezes. This is believed to occur mostly over relatively short distances. It can also be spread by touching surfaces contaminated by the virus and then touching the mouth or eyes. A person may be infectious to others both before and during the time they are showing symptoms.
Avoid being around people who have the influenza virus and by touching surfaces which have been exposed to the virus.
Frequent hand washing reduces the risk of viral spreading. Wearing a surgical mask is also useful. Yearly vaccinations against influenza are recommended by the World Health Organization for those at high risk. The vaccine is usually effective against three or four types of influenza. A vaccine made for one year may not be useful in the following year, since the virus evolves rapidly.
If you have the flu how can you avoid spreading it?
When an infected person sneezes or coughs more than half a million virus particles can be spread to those close by. In otherwise healthy adults, influenza virus shedding (the time during which a person might be infectious to another person) increases sharply one half to one day after infection, peaks on day two and persists for an average total of five days, but can be as long as nine days.
Children are much more infectious than adults and shed virus from just before they develop symptoms until two weeks after infection. In immunocompromised people, viral shedding can continue for longer than two weeks.
Influenza can be spread in three main ways – by direct transmission (when an infected person sneezes mucus directly into the eyes, nose or mouth of another person); the airborne route (when someone inhales the aerosols produced by an infected person coughing, sneezing or spitting) and through hand-to-eye, hand-to-nose, or hand-to-mouth transmission, either from contaminated surfaces or from direct personal contact such as a handshake.
As the influenza virus can persist outside of the body, it can also be transmitted by contaminated surfaces such as banknotes, doorknobs, light switches and other household items. The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about 15 minutes on dry paper tissues, and only five minutes on skin. However, if the virus is present in mucus, this can protect it for longer periods (up to 17 days on banknotes).
How many different strains of the virus are there and what does that mean?
Three types of influenza viruses affect people, called Type A, Type B, and Type C. Each of the three types of influenza have multiple subtypes. The virus mutates into different forms and when these are sufficiently divergent they are delineated by a different sub name.
Last year one of the viral strains mutated further and last year’s influenza vaccine was less effective than usual.
How does the flu vaccine work?
The flu virus is grown in fertilised chicken eggs and the virus is inactivated (it is no longer a live virus). The patient’s immune system responds to the inactivated virus and is already prepared when it encounters the live virus. The patient cannot get the flu from it. They should then have some immunity to the live virus. The following subtypes of virus are inoculated against in this year’s vaccine, for the 2018 Southern Hemisphere influenza season:
• an A/Michigan/45/2015 (H1N1)pdm09-like virus
• an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus
• a B/Phuket/3073/2013-like virus
WHO recommends that quadrivalent vaccines containing two influenza B viruses should contain the above three viruses and a B/Brisbane/60/2008-like virus.
Who should get the flu vaccine?
Centers for Disease Control and Prevention (CDC) recommend that everyone except infants under the age of six months should receive the seasonal influenza vaccine. People who are at high risk of serious complications if they catch the flu include pregnant women, children over six months, the elderly, and people with chronic illnesses or weakened immune systems, as well as those to whom they are exposed, such as health care workers.
Is it true that it gives you the flu?
As it is not a live virus, it cannot give anyone the flu, but due to the immune response may give some mild flu like symptoms.
How long does it take for the flu vaccine to be effective?
One to two weeks.
How often do you need to need to get the flu vaccine?
Each year. Firstly, because the
effectiveness of the vaccine begins to wain by about 10 per cent each month from the fourth month and secondly because each year different strains of the virus predominate.