Updates from Sierra Nevada Memorial Hospital and Hospital Foundation
This is the time of year we are encouraged to get a flu shot. Influenza, or the flu as it is known, is an infectious disease caused by an influenza virus. The flu affects people differently, but common symptoms include fever, runny nose, sore throat, muscle and joint pain, headaches, and coughing.
Worldwide, there are three to five million severe influenza cases each year. The first clearly recorded epidemic struck Europe in 1173. In the early 20th century, Fujikawa in Japan developed the first comprehensive review of epidemic records. His documentation listed 46 epidemics between 862 and 1868. The human influenza A virus was discovered in 1933 after Robert Ellis Shope (an American virologist, epidemiologist and public health expert) isolated the swine influenza A virus in 1931. Since that discovery, studies have made immense progress contributing greatly not only to virology, but also immunology and molecular biology.
Large influenza outbreaks are known as pandemics. In the 20th century, four pandemics have occurred. The 1918 Spanish influenza resulted in millions of deaths. Over two million died from the Asian influenza in 1957. The Hong Kong influenza took over one million lives. Recent COVID-19 statistics indicate over 37 million cases resulting in 1.08 million deaths.
Influenza originates among birds and other animals, however, it spreads person to person. This is unlike infectious diseases like the measles which only occur in one form. Additionally, the influenza virus can change year to year.
As we enter flu season, there are questions about the differences between COVID-19 and the flu. The only true way to differentiate between the two is through testing. The symptoms are very similar although COVID-19 seems to spread faster from person to person and can take longer before people show symptoms. Most people that have flu symptoms are contagious for one day before showing symptoms. COVID-19 can spread well before someone shows signs and can remain contagious for at least 10 days after testing positive. And yes, it is possible to have COVID-19 and the flu at the same time.
The other big difference is we have vaccines for most forms of the flu except COVID-19. Vaccines are made by taking viruses or bacteria and weakening them so they can’t replicate. There are four ways that viruses are weakened by vaccines. You can weaken the virus genes through a technique called cell culture adaptation. This is how measles and mumps vaccines are made. You can destroy the genes completely as the polio vaccine does. You can use a part of the virus as they do with Hepatitis B meaning the virus can’t reproduce. Finally, if you take the toxin that is released from the bacteria and purify it, it can’t do any harm. Examples of this are diphtheria, tetanus and whopping cough. While there has always been controversy about vaccination, there is no doubt that vaccines play an important role in protecting the health of our most vulnerable and at-risk population.
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