Difference between antibodies from natural infection and Covid-19 vaccine

Antibodies are proteins made by the immune system in response to an infection or vaccination. They are present on the surface of the B cells of the immune system. Other immune cells called T cells help clear the infection.

The test can detect the body’s level of antibodies against a certain virus. When the test detects antibodies, it means a person has been previously infected or vaccinated for a disease. Thus, antibodies are a signal that an individual is likely to be protected from future infection. That is why scientists are very interested in understanding the role of antibodies in Covid-19.

Antibodies from natural infection

When you develop antibodies through an infection, the immune system responds to protect the body. It first goes through a process of identifying the virus and finally produces effective antibodies.

For example, having Covid-19 may help protect against reinfection in the short term, perhaps 3 months to a year. Differences in arrival times are caused by a combination of factors, including individual susceptibility as well as level of exposure.

In a 2022 study, researchers concluded that reinfection after natural infection was seven times more likely to be associated with a risk than after vaccination. These data were aggregated before the Delta and Omicron variants were born. Since these variants are more contagious, the rate of reinfection may be higher. Another study found that the risk of reinfection after vaccination with a single dose of Pfizer vaccine was reduced by 82% compared with people who were previously infected but not vaccinated. This result reflects data from the Delta variant.

People with symptoms of Covid-19 also produce effectively neutralizing antibodies. Infection with Covid-19 and subsequent vaccination offers the strongest protection against reinfection. The Covid-19 vaccine is recommended even for people who have recovered from a viral illness because people’s immune systems respond more consistently to the vaccine than to the infection.

Because the human immune system reacts differently to natural infection, it is difficult for scientists to determine how long natural immunity to Covid-19 can persist. In a study published early in the pandemic, researchers found antibodies three months after experiencing symptoms.

Another study published in November 2021 looked at the antibody response to the Pfizer vaccine over a longer period of time. The researchers found that, after the second dose, the antibody responses decreased after 3 months and continued to decrease after 6 months. At 6 months after the second dose, the antibody response was similar to that of people recovering from Covid in terms of levels after the first dose. They also found that the elderly had less antibody responses. In addition, experiencing more side effects from vaccines correlates with stronger protection. How long immunity lasts can also be affected by whether a person has an asymptomatic, mild or severe infection.

In a nutshell, naturally acquired immunity occurs after infection with a particular disease. This usually protects against reinfection, at least in the short term. How long natural immunity lasts depends on the virus and how quickly it mutates.

Antibodies from vaccination

Vaccination is a way for the body to build protective immunity without having to get sick first. Different vaccines do this in different ways. Basically, the mechanism of action of vaccines is the same. Specifically, they expose the immune system to one or more proteins from a virus (or another pathogen). That exposure instructs your immune system to make B cells. Those B cells then make specific antibodies that can fight a particular virus.

Vaccination prompts the body to make memory B cells, just as they do during natural infection. If you are exposed to the virus again, these B cells become active immediately and release antibodies that can target the virus. These antibodies stop the virus before you get sick, or, to a lesser extent, get sick. That’s because the immune system got a head start through vaccination.

There are similarities and differences between vaccine immunity and natural immunity. For example, in response to an infection or vaccination with a live virus, IgM antibodies are usually produced first, followed by IgG and several other antibodies. As in a natural infection, protective immunity does not begin immediately upon vaccination. It takes several weeks or longer for the immune system to form the necessary antibodies and group of B cells.

For the most part, the antibodies formed from vaccination are the same antibodies you would get from a natural infection. The difference is that some vaccines show only the partial immune system of the virus involved. As a result, the immune system does not form as many different types of antibodies as during a natural infection. However, this does not mean that antibodies formed from immunization are any less effective than natural infection.

Most Covid-19 vaccines only show part of the virus’s immune system. This is a protein chosen to trigger a strong immune response.

Vaccines introduce proteins from the virus into the body. This prompts the body to make B cells and antibodies to fight the virus if you are exposed. Therefore, vaccination helps each person to avoid becoming seriously ill. Vaccine immunity and natural immunity may differ in the types of antibodies produced against the virus, however, they both work to prepare the body’s immune system for antibodies. The big benefit of vaccine immunity is that you don’t have to risk the complications of the disease to develop antibodies against the virus. This is even more significant in the case of the Covid-19 epidemic.

Quick comparison table between vaccine immunity and natural immunity:

Equanimity (according to Verywell Health)