Yes Or No to Influenza Vaccine?

           My previous posts were focussed on antigenic characteristics of influenza virus and effectivity of vaccines against influenza virus. Now I am trying to explore in-depth information about influenza vaccine and whether to vaccinate or not.

           When the vaccine against influenza virus was released for the first time, there was much controversy related to its use and efficacy.We all know that immunization is essential for protecting individuals from a particular disease. But there are no vaccines devoid of risks and complications. This was in fact evident with the swine influenza epidemic that occurred in 1976, when neurological complications such as Guillian Barre Syndrome and many other complications were observed to arise from the vaccine (Lessler et.al) .  Although novel vaccines are said to confer protection against various diseases, decision making process whether to vaccinate or not is very complex. In fact it is influenced by the perceptions towards a vaccine and risks associated with it. Before administering a vaccine, it is obvious that following questions arise in individuals mind.
Do we have enough knowledge about the side effects of the newly developed vaccines?
Are there more side effects yet to be discovered?
What is the rate of effectivity of the vaccine?
Is it worth the risk to be vaccinated when the vaccine is available?

                                                     Source: everydayreadiness.com 
The above picture gives the general information about some ways that help prevent the disease from occurring.
    

                               Source: CDC

                                                             Source: NBC News

            It is not unjustifiable that  individual without any risk factor and good health may show reservation about receiving the vaccine because if they get infected with the virus they will develop a natural immunity against the virus. However, it is strongly recommended by CDC  to vaccinate for those having health problems, elderly people, pregnant women and children who are classified as risk group population. 

While CDC emphasizes for vaccination against flu claiming the effectiveness of vaccine to be 59% , the above mentioned data from research conducted by Lessler et.al reveals the possible side effects of the vaccine. Similarly the above mentioned NBC news video shows the probability of occurrence of mutation in the viral genes could result in the worthlessness of the available vaccine. Many people who endorse flu vaccine programs claim that it saves health care cost, ensures better health and protects fellow workers and family members from contracting the flu. I surmise these goals are awesome. They even claims that vaccines have caused decline in the infection. But i don't  think the vaccines have clearly demonstrated effectiveness and safety over time even though the rate of infection has declined. Based on this declined rate of infection, it is not entirely convincing that vaccines are effective but it could also be the result of improved health conditions, better nutritions, awareness in people about infectious diseases and safer drinking water.  Based on the above mentioned sources, it is beneficial to vaccinate  those who are considered risk group population and let the healthy individual develop natural immunity against the virus after being infected. If any serious complication occur they will still have antiviral treatment. But still more questions are yet to be addressed. If pregnant women are in high risks for flu and if they are vaccinated, what would be the side effects on fetus/ babies? If the effectiveness of the vaccine for elderly people is low, why should they be vaccinated? Does their immune system get activated by administering the vaccines? I will look for answers to these question in my further research.  
So, in conclusion if you wish to take a vaccine, take it but be informed about the risks and side effects of the vaccine.    

Work Cited:
Lessler, J., Cummings, DA., Fishman, S., Vora, A., Burke, DS., "Transmissibility of swine flu at Fort           Dix,  1976". J R Soc Interface 4 (2007):755-62. Print.

How Effective Is The Flu Vaccine?

Antigenic Shift and Antigenic Drift in influenza viruses has created a challenge to the modern medical fields. As it is a common characteristic of an influenza virus to change over a period of time, question arises about the effectivity of the vaccines that has been developed against these viruses. Effectivity of the vaccine is not only dependent on the virus but is also dependent on the person who is being vaccinated. Various factors may play an important role in this, but basically personal health state, age and the similarity of the flu virus that the vaccine is developed for, determines the effectivity. As long as the community flu virus matches with the flu vaccine then the effectivity is high, if not then it could turn ineffective.

The effectivity of the flu vaccine differs from person to person. Effectivity percentage in adult is higher compared to the young children and older people. It is obvious that the body immunity goes downhill when we get older and thus flu virus is more dangerous for older peoples. It is thus important for  the older people as well as people with debilitated health conditions and children to get flu vaccines. The following table shows the effectivity of  influenza vaccine from a research that was conducted in Canada.

                         Source: Eurosurveillance

           The effectivity of the vaccine depends upon an individual's immune system. Individuals with weak immune systems experience less effectivity of vaccine. This can happen in persons with chronic diseases. According to CDC the flu vaccine reduces the risk of hospitalization by 30 % to 70% in person with chronic diseases. Thus although there are some controversies about the flu vaccines, it is important that we get vaccine every year. While saying so, do we really need to vaccinate? Do we really know the side effects of the vaccine? What if the influenza virus mutate by the time we vaccinate? Does it worth vaccinating in such situation? My research will be focussed on these question and i will be trying to explore more information about the above mentioned questions. 

Antigenic Shift and Antigenic Drift in Influenza Virus

        My exploratory blog is intended to research on influenza virus and i am trying to explore some informations from different sources. This is an academic learning process of using blogs in blogging site and thus i would like to apologize if any mistakes are encountered, hopefully not. Any kinds of  suggestions and comments on this post are highly anticipated and welcomed. 

Influenza, also called as 'flu' is a viral infection caused by a virus named influenza virus. This virus is typically spherical in shape, with a diameter of 80 to 120 nm (Nanometer) but pleomorphism is very common for this virus. It is common for this virus to be in  filamentous form and is visible under the dark ground microscope. The virus remains viable at 0-4 degree Celsius for about a week and remains viable on fomites such as towels for about two weeks. Influenza (infection) is an acute respiratory disease which occurs in sporadic, epidemic and pandemic forms. 

  

        
Source: Nature Review/ Microbiology


Influenza viruses are of three types; type A, type B and type C. Type A and type B virus infects human beings, fowl, guinea pig and some other species whereas influenza virus type C infects fowl only. Avian(bird) influenza is a disease caused by infectious avian influenza type A viruses. Based on the molecular characteristics and their ability to cause disease and mortality in chickens in a laboratory settings, Influenza type A are classified as highly pathogenicity avian influenza (HPAI) or low pathogenicity avian influenza (LPAI). Type A influenza viruses can be divided into different strains and subtypes based on the structural component ( proteins) present on the surface of the virus. The two structural protein found on the surface of the virus are called hemagglutinin and neuraminidase. Based on these proteins the virus is divided into 18 different hemagglutinin subtypes(H1 through H18)  and 11 different neuraminidase subtypes (N1 through N11). For example H5N1 strain designates an influenza virus A  with Hemagglutinin(HA5) and Neuraminidase(NA1) 

                                                                       

 

Source: Dreamstime.com

One of the interesting feature of influenza virus that fascinated me is their ability to change constantly over a period of time. These changes are of two types called ''antigenic drift'' and ''antigenic shift''.The above figure shows the structural components in an influenza virus. Antigenic drift refers to those small changes in the genes of the viruses that takes place continually when the virus multiplies. The new virus emerged after antigenic drift is closely related to the parent strains and share most of the common properties. But over a long time these changes may accumulate together and thus the newly developed virus become different than the parent strain. This creates a problem in the influenza vaccine we administer every year. Vaccines used this year may not work for next year because of the changes that takes place in influenza virus due to "antigenic drift". This is the reason why we get flu vaccine every year. On the other hand, when the protein component (hemagglutinin and neuraminidase) of the viruses change, either one or both, new influenza virus is emerged and this process is called antigenic shift. "Such a “shift” occurred in the spring of 2009, when an H1N1 virus with a new combination of genes emerged to infect people and quickly spread, causing a pandemic"(CDC). Antigenic drift takes place very often whereas antigenic shift takes place once a while. 

This peculiar characteristics of influenza virus has always created questions on the effectivity of the flu vaccines. Thus, in my latter post i will be trying to find answers to the following questions:
How effective are the available vaccines?
Does the available vaccines equally effective for children, adult and old peoples?