Active vs. Passive Immunity, and how they matter with COVID-19?

Active vs. Passive Immunity

Both types of immunity Active and Passive are the potential treatment of coronavirus infection, and yes, they both play a role in ultimate protection as well.

Thankfully, more than 450,000 people have reportedly recovered from COVID-19, and the number keeps ticking up, according to Johns Hopkins, its good news if someone has contracted and ultimately healed from the virus. Still, it doesn’t mean they’re exempt from re-infection. 

Yes, re-infection is still possible, but worry not! Here, our immunity comes into play; currently, researchers and scientists aren’t yet sure how the human body responds to SARS-CoV-2 is, and for how long it lasts.

For the most, the word ‘immunity’ combines thoughts of complete protection from illnesses, but it’s much more complicated than this. Generally, a human body achieves immunity to disease through proteins produced by the body or the presence of antibodies that neutralize or destroy toxins or other disease carriers.

Jaimie Meyer, MD, says, “These are our ‘attack mechanisms’ against ‘invaders.'” The present antibodies in our bodies are disease-specific; this is the reason why having our flu shot, our immunity is useless against the current coronavirus outbreak.

Talking about immunity, it can be broken down into two different categories: active and passive immunity – these differences depend on how your body is responded to the virus or bacteria it has antibodies for, and for how long they can prevent those respective diseases. 

The good news: Both types are essential for the potential treatment of COVID-19 and future protection.

What is active immunity?

The CDC explains, “active immunity results when exposure to a disease organism triggers the immune system to produce antibodies to that disease,” and can happen in two ways. Natural immunity and vaccine-induced immunity, earlier include having infection with the actual disease, and the latter is done via a vaccination.

Active immunity – either situational/natural or vaccine-induced – allows a person’s immune system to recognize the disease, especially the one that ever comes into contact with it again, then triggers the body to produce the needed antibodies to fight it off.

Active immunity is often long-lasting and sometimes provide life-long protection, based on the disease itself like, immunity to the varicella virus (chickenpox) – either via acquiring the infection or through a vaccine – provides lifelong immunity or protection for up to 10 to 20 years. 

Whereas a yearly flu shot should be repeated, as it provides the protection for the first three months, and begins to lose its effectiveness after six months; it’s also important to note that active immunity takes several weeks to develop.

While research is going on with the immunity of the pertains to COVID-19, according to Dr. Meyers, both natural and vaccine-induced immunity may provide protection against coronavirus, but who knows when the vaccine trials will end, and the vaccine will widely be available.

What is passive immunity?

Active immunity occurs when an individual produces antibodies to disease by their own immune system, while passive immunity is when antibodies are given. This happens in utero or when antibody-containing blood products – such as immune globulin, or a substance made from human blood plasma – administered ONLY when immediate protection from a specific disease is needed. 

Explained by Dr. Meyer, “For example, when a mother’s antibodies cross the placenta to the fetus or when people are given antibodies as a treatment for rabies,” 

Immune globulin is also providing protection against hepatitis A when the vaccine is not recommended. 

The best thing about passive immunity is that it’s sometimes used as a treatment against diseases, and provides immediate protection, but doesn’t last as long as active immunity, and loses effectiveness in a few weeks or months.

Of course, this passive immunity may also be helpful when it comes to COVID-19 – primarily via potential use of convalescent serum or blood plasma collected from previously recovered from COVID-19. 

As Dr. Meyer said, “Giving antibodies from the blood of people who have recovered from COVID-19 to people who are actively ill to prevent complications and hasten recovery.” 

The use of convalescent plasma isn’t new; it’s also been used to treat other infectious diseases, including the Middle East respiratory syndrome (MERS), Ebola, SARS, and even the H1N1 and H5N1 infections.

And, convalescent plasma as a treatment for COVID-19 is still being studied and is not yet recommended as a treatment by the US Food & Drug Administration.


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