Active vs Passive immunity: What is the difference between COVID immunity

Our immune system produces antibodies in response to the virus stored in its memory for the future. Our immune system reacts promptly to fight the virus when it comes in contact with it again. For the uninitiated, our body provides two types of immunity against the virus- active and passive. They both are acquired and last differently.

Whenever any pathogen enters our body, our immune system produces defensive proteins to fight them which are called antibodies. These antibodies are produced exactly according to the organism. They recognise the invader with the help of proteins on its surface called antigens.

Antigens target the intruder and either kill it directly or lock it to be neutralised by other immune cells. There are mainly two types of antibodies produced by our immune system when it comes in contact with the virus- Immunoglobulin M (IgM) and Immunoglobulin G (IgG).

Immunoglobulin M (IgM): Our internal system produces this antibody first after coming in contact with any diseases causing pathogens.

Immunoglobulin G (IgG): IgM antibodies are produced later by the immune system and act as a memory cell.

Active immunity refers to the production of antibodies in response to the presence of an antigen. It is produced by the immune system when the body is triggered to produce antibodies to fight disease. An active antibody is produced in two ways:

Natural infection: You gain antibodies after coming in contact with the virus.

Vaccination: This type of immunity is gained by receiving a weakened form of a pathogen through vaccination.

People who are infected with coronavirus develop antibodies within 2 weeks after exposure to the virus. But how long it protects us is still unknown. Some studies carried out in this matter revealed that COVID-19 immunity might not last long. Another study revealed that the antibody level drops sharply a few months after recovering from COVID-19. A lot more research is needed in this area to know how long the immunity lasts.

Passive immunity refers to antibodies that are passed on to an individual rather than producing them on their own. Like a newborn acquires immunity from its mother through the placenta. Another way could be through plasma transfusion from the recovered person to the infected person. In case of passive immunity, the protection is immediate, but unlike active immunity, it does not provide long-lasting protection.

Researchers are still trying to find out the use of a blood product called convalescent plasma in producing passive immunity. Studies are still being carried out to understand how effective such therapies are and to understand the usage of therapy in the long run.

How many antibodies our immune system will produce and how long it will last is not in our control. But some factors may weaken your immune system such as:

Old age

Medication that suppresses immunity

Organ transplant

HIV or AIDS

Treatment for cancer

Immunodeficiency disorder

Low nutrient diet

Sleeplessness

Stress

Obesity

Smoking

Excessive alcohol intake