Why you should get the COVID-19 vaccine

(Conversation) A few weeks ago, a message appeared in the corner of the screen. “What do you think about people who have recently been vaccinated with COVID-19?” My friend was eligible for the COVID-19 vaccine but recently survived a SARS-CoV-2 infection. Every week, more and more people are qualifying for the vaccine, including millions who have already recovered from a coronavirus infection. Many people, especially those who are already infected, are wondering if they need a vaccine.

I am studying the immune response to respiratory infections, so I get a lot of questions of this kind. A person can develop immunity (the ability to resist infection) by being infected with a virus or being vaccinated. However, immune protection is not always equal. SARS–CoV–2 vaccine immunity and innate immunity vary widely in the strength of the immune response, the length of time the defense lasts, and the individual variation of the immune response. The COVID-19 vaccine provides safer and more reliable immunity than natural infections.

Immunity after infection is unpredictable

Immunity comes from the ability of the immune system to remember infections. Using this immune memory, the body will know to fight if it encounters the disease again. Antibodies are proteins that can bind to viruses and prevent infection. T cells are cells that direct the removal of infected cells or viruses to which antibodies are already bound. These two are some of the major players contributing to immunity.

After SARS-CoV-2 infection, the reaction between human antibodies and T cells may be strong enough to provide protection against reinfection. Studies show that 91% of people who develop antibodies to the coronavirus are unlikely to be re-infected for six months, even after a mild infection. People who are asymptomatic during the infection may also develop immunity, but they tend to produce less antibodies than those who feel sick. Therefore, innate immunity may be strong and long-lasting for some people.

The problem is that not all people develop immunity after SARS-CoV-2 infection. 9% of infected people do not have detectable antibodies, and up to 7% do not have T cells that recognize the virus 30 days after infection.

For those who develop immunity, the strength and duration of protection varies greatly. Up to 5% of people can lose their immune protection within a few months. Without strong immune defenses, these people are vulnerable to reinfection with the coronavirus. Some people had a second seizure of COVID-19 one month after the first infection. And, rarely, some people are hospitalized or die.

Reinfected people may be able to get the coronavirus even if they feel sick. This can endanger the person’s loved ones.

And what about variants? So far, there are no definitive data on new coronavirus variants and innate or reinfection, but it is certainly possible that immunity from one infection is not very strong against another variant of infection.

Vaccination leads to reliable protection

The COVID-19 vaccine produces both antibody and T cell responses, which are much stronger and more consistent than immunization from natural infections. According to one study, four months after receiving the first dose of the Moderna vaccine, 100% of the people tested had antibodies to SARS-CoV-2. This is the longest period ever studied. In a study examining the Pfizer and Modana vaccines, antibody levels were much higher in those who were vaccinated than in those who recovered from the infection.

Even better, a study in Israel showed that the Pfizer vaccine blocked 90% of infections after both doses. This is true even if there are variants in the population. Also, as infections decrease, people around you are less likely to get the virus.

The COVID-19 vaccine is not perfect, but it produces powerful antibody and T cell responses that provide a safer and more reliable defense than innate immunity.

Infection and vaccination together

In response to a friend’s message, I immediately replied that she should definitely be vaccinated. After being vaccinated, my friend was relieved to know that she had long-lasting and effective immunity and was unlikely to spread the coronavirus to her friends and family.

But since I sent that message, better news has come out. A new study showed that post-infection vaccination produced six times as many antibodies as the vaccine itself. This does not mean that everyone needs to attempt an infection before being vaccinated. Vaccine immunity alone is powerful enough to provide protection, and the risk of fighting COVID-19 far outweighs the benefits. But when my friends and many other people who are already infected are vaccinated, they are well protected.

Innate immunity from infection is simply too unreliable in the face of such devastating viruses. The current COVID-19 vaccine provides the vast majority of people with incredibly strong and consistent protection. Therefore, the COVID-19 vaccine offers immeasurable benefits to qualified individuals, even those who have been infected with SARS-CoV-2.

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This article has been republished by The Conversation under a Creative Commons license. Read the original article here: https://theconversation.com/why-you-should-get-a-covid-19-vaccine-even-if-youve-already-had-the-coronavirus-155712..