What is active and passive immunity ?
With no vaccine for the virus yet, the only option we have to keep ourselves safe from the virus is by keeping our immune system strong. When someone contracts COVID 19 and heals from it, it doesn’t mean they are entirely safe from not getting the infection again. While most of the people think of the word immunity as something that protects them completely from the illness, but actually it’s much more complicated, says the Center for Disease Control and Prevention.
How do we become immune to a disease?
A person achieves immunity to disease through the presence of antibodies or proteins produced by the body that can destroy or neutralize the toxins or other disease carriers. These antibodies are our attack mechanisms against invaders. But these antibodies are specific for specific diseases, which is why even if you got the flu shot this year, you have no immunity against the current coronavirus outbreak.
Two types of immunity
Our immunity can be divided into two categories – active and passive immunity. The difference between both depends on how the body was introduced to virus or bacteria it has developed antibodies for and to what extent and for how long they can prevent against future disease. The thing to be noted is that both types of immunity can play a role in the future protection treatment of COVID 19.
What is active immunity?
According to the CDC, active immunity is developed when exposure to a disease organism triggers the immune system to produce antibodies for that disease. This can happen in two ways – through infection with the actual disease, which is called natural immunity or through vaccination (a killed or weakened form of the disease that won’t make someone ill but triggers the body to make antibodies), which is called vaccine-induced immunity.
Active immunity isn’t immediate and can take several weeks to develop. That is why most doctors recommend getting the flu shot before the flu season kicks in.
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There is much more research needed in the context of immunity against COVID 19. While the vaccine-induced immunity is still a huge question mark, researchers are currently looking at the immunity gained by people who have recovered from COVID 19.
According to the World Health Organisation, it’s still unknown whether those previously infected with COVID 19 can be re-infected and what type of immunity they have against the virus.
A person who has generated a full-blown response with detectable antibodies is expected to have protection for a period of time. But we don’t know how long that period would be, added the WHO.
What is passive immunity?
While a person develops active immunity when their body produces antibodies to disease through its own immune system, passive immunity is when a person is given antibodies. This happens in utero or through antibody-containing blood products, such as immune globulin, which is administered when immediate protection from a specific disease is needed. For instance, immuno globulin can provide protection against hepatitis A in instances when hepatitis A vaccine is not recommended.
The major advantage of passive immunity is that it provides immediate protection. But passive doesn’t last long as active immunity and loses its effectiveness within a few weeks and months, as per CDC.
Passive immunity may also be helpful when it comes to COVID 19. This can be done primarily through the potential use of convalescent serum or blood plasma collected from those who have previously recovered from COVID 19. This means giving antibodies from the blood of people who have recovered from COVID 19 to people who are actively ill. This can help prevent complications and fasten the recovery.
Convalescent plasma as a treatment for COVID-19 is still being studied and has not been yet recommended as a routine treatment. Researchers are hoping to use the technique to treat COVDI 19 patients and boost the immune system of health care providers and first responders.
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