• Aniruddh

Viruses and Vaccines 101


Today’s edition of the blog talks about viruses and vaccines, in general. This blog will be followed by another in the coming weeks with information specific to Covid-19. I think some amount of basic information is useful before we get into the specifics of Covid-19. I hope this primer is helpful.


What is a virus?

A virus is a particle made of chemicals called proteins and nucleic acids.

  • The proteins (all purple and red structures in the image) mainly form the boundary of the virus.

  • Inside this boundary are the nucleic acids (all green structures in the image). The nucleic acid is the genetic material of the virus. All living things have genetic material.

All purple and red structures are the proteins on the boundaries and the green structures in the centre are nucleic acids.
An illustration of a virus. Source: Wikipedia Commons.

All living things are made up of cells. A virus is not active when it is outside a living cell. A virus almost behaves like a dust particle outside the cell. However, when a virus meets a cell, it goes into the cell and begins to multiply. This multiplication increases the number of viruses. Once the number of viruses is above a certain number, the cell or the individual who has the virus begin to show disease symptoms. The individual or cell where the virus is replicating is called a host.


Viruses cause a wide range of diseases not only in humans, but also in plants and animals.


How does the virus harm the body of the host?

Different viruses harm the host bodies in various ways. Some, like the influenza virus cause relatively mild symptoms of a temporary cold, cough and sometimes fever. Other viruses like the polio virus can cause a debilitating paralysis in the host.


Can the host protect itself from viruses?

Yes, absolutely. There are many viruses and other disease-causing agents known as pathogens that we encounter daily. We have an immune system that protects us from


pathogens. As soon as the immune system detects a pathogen, it looks to destroy it. Such quick and efficient destruction of pathogens means that there is no time for the pathogen to multiply and cause the disease. Sometimes our immune system is overwhelmed, and the virus (or other pathogens) can multiply in our body and cause the symptoms of the disease. That is why we sometimes get a cold, or some of us have even had the Covid-19 disease.


What roles do vaccines play in disease control?

The symptoms of a common cold are relatively mild, and if sometimes our body’s immune system cannot stop the virus from multiplying, we have the disease. Eventually, in a week or so,


our immune system can fight off the virus, and we feel fine. In such a case, having a disease has a relatively small effect on the body. However, if the immune system cannot stop the polio virus, it could make a life altering change in the person’s life. In such situations, vaccines help. Taking a vaccine against polio can give the person protection from the polio virus for a lifetime. This is how vaccines help with disease control. In fact, vaccines and a herculean vaccination drive in India has ensured that the wild polio virus is completely eradicated from India. India’s last case of naturally occurring polio was in 2001.


How do vaccines work?

Vaccines are chemicals that are produced by scientists to fight against specific diseases. These vaccines are rigorously tested first in the laboratory and then in field trials (on humans). Once the efficacy (how well the vaccine works in preventing the disease) and safety (no adverse effects of the vaccine) are ascertained, vaccines are available to the public.


Vaccines help in getting the immune system ready for a pathogen attack. When a pathogen enters a body, the immune system fights it through a series of responses. The vaccine causes a similar series of responses in the immune system even in the absence of the pathogen. This means that the immune system is ready to face the pathogen when it arrives.


Are vaccines safe? Do vaccines cause autism in children?

All vaccines that are developed against diseases go through a rigorous scientific protocol of testing, without which they are not released to the public. As mentioned before, the vaccine is tested for its efficacy and safety. Vaccines do not cause autism in children.


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