What is Influenza?
Simply stated, influenza is an infection of the upper airway caused by a virus,but one that has wiped out millions of humans over the past one hundred years or so.
Ontario’s Ministry of Health and Long-term Care tells us that influenza is responsible for approximately 12,200 hospitalizations every year in Canada… and an average of 3,500 deaths.
Note:In the interest of transparency, these numbers are generally accepted to be statistical ‘guesstimates’ based on data compiled from acute health care facilities, but there is no definitive tracking of influenza deaths in Canada. This is largely because influenza triggers so many other health issues – pneumonia, respiratory distress and heart attacks among them – that often get listed as a cause of death. That said, it in no way diminishes the seriousness of the illness – you definitely do not want to get it! – and the fact is that it does kill people, especially older Canadians.
Accordingly to Wikipedia, the influenza virus is commonly (but misleadingly)known better as the ‘flu’ and, as said earlier, is an infection caused by an influenza virus. Symptoms can be mild to severe, but the most common symptoms include…high fevers, runny noses, coughing, sore throats, sneezing, muscle pains, headaches 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 diarrhea and vomiting, but these are not common in adults. Diarrhea and vomiting occur more commonly in gastroenteritis, which is an unrelated disease and sometimes inaccurately referred to as ‘stomach flu’ or the ‘24-hour flu’.Complications of influenza may well include viral pneumonia, secondary bacterial pneumonia, sinus infections, and worsening of previous health problems such as asthma or heart failure.
Is There More Than One Type?
Three of the four types of influenza viruses affect humans: Type A, Type B, and Type C. Type D has not been known to infect humans, but is believed to have the potential to do so. 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.The infection may be confirmed by testing the throat, sputum, or nose for the virus. A number of rapid tests are available; however, people may still have the infection even if the results are negative. A type of polymerase chain reaction that detects the virus’s RNA is more accurate.
Influenza spreads around the world in yearly outbreaks, resulting in about three to five million cases of severe illness requiring hospital visits/stays and about 250,000 to 500,000 deaths.About 20% of unvaccinated children and 10% of unvaccinated adults are infected each year.In the northern and southern parts of the world, outbreaks occur mainly in the winter; around the equator, outbreaks may occur at any time of the year.Death occurs mostly in the young, the old, and those with other health problems.Larger outbreaks known as pandemics are less frequent.In the 20th century, three influenza pandemics occurred: the Spanish influenza in 1918 (20 to 50 million deaths), the Asian influenza in 1957 (2 million deaths), and the Hong Kong influenza in 1968 (1 million deaths).The World Health organization declared an outbreak of a new type of influenza A (H1N1) to be a pandemic in June 2009.Influenza may also affect other animals, including pigs, horses, and birds.
What Can You Do?
- Frequent and regular hand washing reduces the risk of viral spread
- Clean and disinfect commonly/frequently used objects and surfaces that are touched often.
- Cough or sneeze into your shirt sleeve rather that into your hands or into the air.
- Discard used tissues promptly in the waste basket or garbage.
- Isolate yourself at home when you are ill.
- Wearing a surgical mask is also useful.
- Get annual vaccinations against influenza, or better still,
- Get the high-dose influenza vaccine shot if you are over 65 and/or have a compromised (in any way) immune system.
…but the best thing to do by far is…
The vaccine is usually effective against three or four types of influenza. It is usually well-tolerated. A vaccine made for one year may not be useful in the following year, since the virus evolves rapidly. Antiviral drugs such as the neuraminidase inhibitor oseltamivir, among others, have been used to treat influenza. The benefit of antiviral drugs in those who are otherwise healthy do not appear to be greater than their risks. No benefit has been found in those with other health problems.
What is in the flu vaccine?
The 2018-19 seasonal trivalent and quadrivalent vaccines contain:
- A/Michigan/45/2015 (H1N1)pdm09-like virus
- A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus
- B/Colorado/06/2017-like virus
- B/Phuket/3073/2013-like virus (in quadrivalent vaccines only)
The A/Singapore and B/Colorado strains were not contained in the 2017/18 season vaccine.There are several inactivated influenza vaccines and a live attenuated influenza vaccine available in B.C.
The inactivated vaccines are made of killed influenza viruses and are given by injection. The live attenuated influenza vaccine is made from weakened influenza viruses and is given as a nasal spray.
Publicly-funded influenza vaccines available in B.C. for 2018/19:
- Trivalent Inactivated Influenza Vaccines (TIIV or TIV)
- Influvac® (Mylan Pharmaceuticals)
- Fluviral® (GlaxoSmithKline)
- Quadrivalent Inactivated Influenza Vaccines (QIIV or QIV)
- Fluzone® Quadrivalent (Sanofi Pasteur Limited)
- Quadrivalent Live Attenuated Influenza Vaccine (LAIV-Q)
- Flumist® Quadrivalent (AstraZeneca Canada)