A a few weeks ago, a message appeared in the corner of my screen. “What do you think of people who have recently had COVID-19 against the vaccine?” A friend of mine was eligible for a vaccine against COVID-19, but had recently suffered from a SARS-CoV-2 infection. Every week more people are eligible to receive vaccines, including millions of people who have already done so recovered from a coronavirus infection. Many wonder if they need the vaccine, especially people who have already been infected.
I study immune responses to respiratory infections, so I have a lot of these kinds of questions. A person can develop immunity (the ability to resist infection) from not being infected with a virus or from receiving a vaccine. However, immune protection is not always the same. The strength of the immune response, how long the protection lasts, and the variation in the immune response between people is very different between vaccine immunity and the natural immunity of SARS – CoV – 2. COVID – 19 vaccines offer a safer and more reliable immunity than natural infection.
Immunity after infection is unpredictable
Immunity comes from the immune system’s ability to remember an infection. Using this immune memory, the body will know how to fight if it finds the disease again. Antibodies are proteins that can bind to a virus and prevent infection. T cells are cells that direct the elimination of infected cells and viruses already bound by antibodies. These two are some of the main actors that contribute to immunity.
After a SARS-CoV-2 infection, a person’s antibody and T cell responses may be strong enough to provide them. protection against reinfection. Research shows that 91% of people who develop antibodies to coronavirus are unlikely to become infected again. for six months, included later a mild infection. People who had no symptoms during the infection are also more likely to develop immunity, although they usually do. less antibodies than those who felt bad. Therefore, for some people, natural immunity can be strong and lasting.
The problem is that not everyone will develop immunity after a SARS-CoV-2 infection. Up to 9% of infected people do not have it detectable antibodies, and up to 7% of people they have no T cells that recognize the virus 30 days after infection.
For people who develop immunity, strength and duration of protection can vary greatly. Up to 5% of people can they lose their immune protection in a few months. Without a strong immune defense, these people are susceptible to coronavirus reinfection. Some have had second battles of COVID – 19 so soon one month after their first infection; and, though rare, some people have been hospitalized or even dead.
A person who is re-infected can also transmit the coronavirus even without feeling sick. This could put at risk the loved ones of the person.
And what about the variants? So far, there are no difficult data on new variants of coronavirus and natural immunity or reinfection, but it is true that the immunity of an infection may not be as strong against infection with a different variant.
Vaccination provides reliable protection
COVID – 19 vaccines generate both antibody and T cell responses. – but this is much stronger and more consistent than immunity to natural infection. One study found that four months after receiving the first dose of Modern vaccine, 100% of those tested had antibodies to SARS-CoV-2. This is the longest period studied so far. In a study of Pfizer and Moderna vaccines, antibody levels were also much higher in vaccinated people than in those who had recovered from the infection.
Even better, a study in Israel showed that the Pfizer vaccine blocked 90% of infections after both doses, even with a variant present in the population. I a decreased infections it means that people are less likely to transmit the virus to the people around them.
COVID-19 vaccines are not perfect, but they produce strong antibody and T cell responses that offer a safer and more reliable means of protection than natural immunity.
Infection and vaccination together
In my friend’s message, I responded instantly that I should receive the vaccine. After getting vaccinated, my friend might be comfortable knowing that she has effective and lasting immunity and is less likely to spread the coronavirus to her friends and family.
But more good news has appeared since I sent this message. A new study showed that vaccination occurs after infection six times more antibodies than a vaccine by itself. This is not to say that anyone should try to get infected before getting vaccinated: the vaccine’s immunity alone is strong enough to provide protection, and the dangers of a fight with COVID-19 far outweigh the benefits. But when my friend and many others who were already infected receive their vaccines, they will be well protected.
Natural immunity to infection is too unreliable in the face of such a devastating virus. Current COVID-19 vaccines offer incredibly strong and consistent protection to the vast majority of people. Therefore, for anyone eligible, even those who have already had a SARS-CoV-2 infection, COVID-19 vaccines offer huge benefits.