If you have recovered from Covid-19, are you now immune? Well, the truth is, whether you have recovered from the Covid-19, received the vaccine, or neither, you need to understand how this immunity thing works and how long it lasts. Having this insight will guide how you interact with people during the pandemic.
But first, there are two types of immunity; vaccine-induced and natural.
We will dive into them right away.
How vaccine-induced immunity after receiving immunization works
The Pfizer-BioNTech and Moderna are the two vaccines approved for use in the United States at the moment. The Moderna vaccine is approximately 94% effective in preventing COVID-19, and the Pfizer-BioNTech vaccine is 95% effective.
Both vaccines help the body build immunity to the virus that causes COVID-19 without having to take COVID-19.
Both vaccines require two injections in a few weeks to obtain complete protection.
Once you have maximum protection from the vaccine, your body produces a supply of T cells and B cells that will remember how to fight the virus in the future, similar to natural immunity.
It is critical to mention that it usually takes a few weeks after vaccination for the body to produce T cells and B cells. During this period, you are likely to contract the virus that causes COVID-19 until your body can provide protection.
Asked by the World Health Organization (WHO), Dr. Katherine O’Brien, a professor at the Johns Hopkins Bloomberg School of Public Health, said: “We see an encouraging immune response that starts about two weeks after the first dose. And it is the second dose that then increases this immune response. We see that the immune system becomes even stronger after the second dose, again shorter. “
Researchers do not yet know how long the vaccine’s immunity lasts and whether monitoring will be necessary to protect against new variants of the COVID-19 virus.
Studies are ongoing.
How natural immunity works after COVID-19 develops
Once a person acquires a virus, the immune system preserves its memory.
The National Institutes of Health explains: “The immune cells and proteins that circulate in the body can identify and kill the pathogen if it reappears, protecting against the disease and reducing the severity of the disease.”
The ingredients of immune protection include:
- Antibodies- proteins that circulate in the blood, recognize foreign substances such as viruses, and neutralize them.
- Helper T cells help identify pathogens.
- Killer T cells kill pathogens.
- B cells produce new antibodies when the body requires them.
From findings, people recovering from COVID-19 had all four of these components. However, what this means for the immune response and how long the immunity lasts are unclear.
According to Lauren Rodda, Ph.D., principal investigator at the University of Washington School of Medicine, it is not clear if humans are immune to re-infection because we do not have enough studies.
Understanding in this area continues to expand as new researches are conducted.
More recently, a study published in the journal Science found that immunity can last up to 8 months.
Shane Crotty, Ph.D., a professor at the La Jolla Institute of Immunology in California, led the study. His team measured the four components of immune memory in approximately 200 people exposed to SARS-CoV-2 (caused by covid-19) and recovered.
The researchers found that all four factors remained for at least eight months after infection with the virus.
What this implies is that the body can “remember” SARS-CoV-2. If the virus resurfaces, memory B cells can quickly gear up and produce antibodies to fight it.
Those who have recovered from COVID-19 could have immunity for months or even years, the authors said.
Before this latest study, Ronda said her research team and others had done some work, showing that the antibodies persist for at least three months.
In that study, in particular, even people who had mild symptoms produced antibodies.
Her study also suggested that immunity might last much longer.
In a separate study published in The New England Journal of Medicine, researchers in Iceland studied 1,107 people who had recovered from COVID-19 and tested positive for antibodies.
Over four months, they found that these COVID-19 antibodies did not decrease.
Another research printed in the journal Immunity found that people who recover from even mild cases of COVID-19 produce antibodies for at least 5 to 7 months and could last much longer.
Their team has tested nearly 30,000 people in Arizona since April 30, 2020, shortly after a blood test was developed for the new coronavirus.
What does a positive antibody mean?
If you have received a positive antibody test result, you might be resting easy in the knowledge that you cannot contract COVID-19 again. To be candid, it is a bit more complicated than that.
According to CDC, a positive test result shows you may have antibodies from an infection with the virus that causes COVID-19. However, there is a chance that a positive test result means you have antibodies from an infection with a similar virus.
Granted having antibodies to the virus that causes COVID-19 may protect from getting re-infected with the virus. But even if this is the case, there is no clearness on how much protection the antibodies may provide or how long this protection may last.
However, a study published on February 24, 2021, in the journal JAMA Internal Medicine found that individuals who tested positive for SARS-CoV-2 antibodies based on commercial antibody tests may have a lower risk of re-infection SARS-CoV-2.
The study analyzed data from more than 3.2 million people in the United States using the SARS-CoV-2 antibody test. The researchers evaluated the data for SARS-CoV-2 infection in people with positive results versus negative results.
The researchers noted that while the risk reduction stayed un-observed for the first 30 days after an initial antibody test, it became more pronounced after 30 days and gradually intensified over the 90-day observation period.
What you should know about the possibility of re-infection
Although there have been recorded cases of re-infection with the new coronavirus, they remain rare, according to the CDC. And even though the virus infection and vaccination may provide some immunity, it is not yet fully understood.
There are ongoing studies to understand:
- the possibility of being infected again,
- how often recurrence occurs
- how soon after the first infection can occur again
- how severe the cases of re-infection are
- Who may have a higher risk of recurrence
- what does contracting Covid-19 again mean in a person’s immunity
- whether a person can transmit SARS-CoV-2 to others when it reappears
Until more is known, in addition to vaccination, the CDC recommends wearing masks, removing yourself, and washing your hands frequently to reduce exposure to the virus or spread it to others.