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ennifer T. Grier, University of South Carolina

A few weeks ago , a message popped up in the corner of my screen. “What do you think about those who have recently had COVID–19 getting the vaccine? ” A friend of mine was eligible for a COVID–19 vaccine, but she had recently gotten over an infection with SARS–CoV–2. More people are becoming eligible for vaccines every week – including millions of those who have already recovered from a coronavirus infection . Many are wondering if they need the vaccine, especially people who’ve already been infected.

I study immune responses to respiratory ailments , so I get a lot of these kinds of questions. Someone can develop immunity the ability to resist infections from becoming infected with a virus or by acquiring a vaccine. Nevertheless , immune protection isn’t always equal . The potency of the immune response, the period of time that the defense lasts and the version of the immune response across individuals is very different between chemical resistance and natural immunity for SARS–CoV–2. COVID–19 vaccines provide safer and more dependable immunity than natural infection.

The immune system will normally generate an immune response to some SARS-CoV-2 infection , but not necessarily . National Institutes of Allergy and Infectious Diseases, CC BY

Immunity after infection is unpredictable

Immunity comes in the immune system’s ability to remember an infection. Using this immune memory, the body will know to fight if it encounters the disease again . Antibodies are proteins that can bind to a virus and protect against infection. T cells are cells that guide the removal of infected cells and viruses bound by antibodies. These two are some of the key players that result in immunity.

After a SARS-CoV-2 disease , a person’s antibody and T cell responses may be strong enough to provide protection against reinfection. Research shows that 91% of people who develop antibodies against the coronavirus are unlikely to be infected again for six months, even after a mild infection. Individuals who had no symptoms during the infection are also prone to develop immunity, even though they tend to make fewer antibodies than those who felt ill . So for some people, natural immunity may be strong and long-lasting.

The problem is that not everyone will develop immunity following a SARS-CoV-2 infection. As many as 9% of infected individuals don’t have detectable antibodies, and up to 7 percent of people don’t have T cells that recognize the virus 30 days after infection.

For men and women that do develop immunity, the strength and duration of the protection may vary a lot. Up to 5% of individuals can lose their immune protection in a month or two . Without a strong immune defense, these people are susceptible to reinfection from the coronavirus. Some have had second bouts of COVID–19 when one month after their first infection; and, though rare, some folks have been hospitalized or even died .

A person who is reinfected may also be able to transmit the coronavirus even without feeling sick . This could place the individual ’s loved ones in danger .

And what about the variants ? So far , there isn’t some hard data about the new coronavirus variants and natural immunity or reinfection, but it’s surely possible that immunity from one infection won’t be as strong against infection with another variant.

COVID–19 vaccines generate a strong immune response in terms of both antibodies and T cells, such as the T cell in this photo. National Institutes of Allergy and Infectious Diseases/National Institutes of Health

Vaccination leads to reliable protection

COVID–19 vaccines create both antibody and T cell responses – but this is much more powerful and more consistent than immunity from natural disease . One study found that four months after receiving their first dose of this Moderna vaccine, 100 percent of individuals tested had antibodies against SARS-CoV-2. This is the longest interval that has been studied so far . In a study looking at the Pfizer and Moderna vaccines, antibody levels were much higher in vaccinated individuals than in those who had recovered from disease .

Even better , a research in Israel revealed that the Pfizer vaccine blocked 90% of infections after both doses – even with a variant present in the populace . And a reduction in infections means people are not as likely to transmit the virus to the people around them.

The COVID–19 vaccines aren’t perfect, but they produce strong antibody and T cell responses that offer a safer and more reliable way of protection than normal immunity.

Infection and vaccination together

To my friend ’s message, I immediately replied that she should absolutely get the vaccine. After getting vaccinated, my buddy could be comfortable knowing that she has long-lasting, powerful immunity and less of a possibility of spreading the coronavirus to her friends and loved ones .

But more good news has emerged since I sent that message. A new study revealed that hepatitis after infection produces six times more antibodies than a vaccine by itself . This isn’t to say that anyone should try and get infected before they get vaccinated – vaccine resistance alone is more than strong enough to give protection and the dangers of a fight with COVID-19 far outweigh the benefits . But when my friend and others who were already infected get their vaccines , they’ll be well shielded .

Natural immunity from infection is just far too unreliable in the face of such a devastating virus. Present COVID-19 vaccines provide incredibly powerful , consistent protection to the great majority of people. Thus , for anyone qualified , even those who have already had a SARS-CoV-2 infection, COVID-19 vaccines provide immense benefits.

Jennifer T. Grier, Clinical Assistant Professor of Immunology,, University of South Carolina

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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