Colombia (United States)
As someone who studies the immune response to infections in the human respiratory system, I am concerned about the news of the emerging coronavirus outbreak. I wonder if vaccination or a previous infection will offer protection against the different forms of SARS-CoV-2? Especially the highly contagious new delta variant, which quickly spread to at least 70 countries.
There are two ways a person can build an immune system to fight infections in their body. The first after being infected with the virus and the second after being vaccinated. However, immune protection is not always the same. Vaccine immunity against SARS-CoV-2 can vary in terms of natural immune strength or duration of protection. Additionally, not everyone will achieve the same level of immunity against infection, while the immune response to vaccines is very consistent.
Vaccines are more likely to be safe
The difference in immune response between vaccination and infection appears to be even greater when there are two of the newer forms. In early July, two new studies were published showing that COVID-19 vaccines are slightly less effective than older strains of the virus, while providing excellent immune responses against newer variants. Researchers looked at how antibodies fight new forms of coronavirus and found that people previously infected with the coronavirus may be more susceptible to the new strains, while those who have been vaccinated are likely to be protected.
COVID-19 vaccines offer a safe and reliable route for immunity against older strains of coronavirus and emerging strains, especially the newer delta variant. Immunity after infection is unpredictable. Immunity comes from the ability of the immune system to remember the infection. By using this immune memory when it encounters any type of virus, the body will know how to fight infection. Antibodies are proteins that can bind to viruses and prevent infection.
unlikely to re-infect for six months
T cells give instructions to eliminate infected cells and viruses already bound by antibodies. These two factors are among the major factors that contribute to immunity. After infection with SARS-CoV-2, a person’s antibody and T cell responses may provide protection against reinfection. About 84% to 91% of people who developed antibodies to the original strains of the coronavirus were unlikely to be re-infected for six months, even after a mild infection.
People who have had no symptoms during infection are also more likely to develop immunity, although they produce fewer antibodies than those who feel sick. So, for some people, natural immunity can be stronger and longer lasting. A major problem is that not everyone will develop immunity after infection with SARS-CoV-2. 9% of those infected do not have detectable antibodies and up to 7% do not have T cells that recognize the virus 30 days after infection.
For people who develop immunity, the strength and duration of protection can vary widely. Up to 5% of people can lose their immune system within a few months. Without strong immune defense, these people are susceptible to reinfection with the coronavirus. Some developed symptoms of COVID-19 for the second time within a month of their first infection; And, although it rarely happens, some people have been hospitalized or died from reinfection. A growing problem is that people who have been previously infected with strains present in the pandemic may be more vulnerable to reinfection with the delta variant.
88% of people still have antibodies 12 months after infection
A recent study found that 12 months after infection, 88% of people still had antibodies that could block infection of cells grown with the original variant of the coronavirus – but less than 50% had antibodies that blocked the delta variant. . Importantly, an infected person may be able to transmit the corona virus without even feeling sick. In this case, the new variants are of particular concern, as they are more easily transmitted than the original strains.
Vaccination offers reliable protection. COVID-19 vaccines generate both antibody and T cell responses – and those responses are much stronger and more consistent than immunity after natural infection. One study found that six months after receiving their first dose of Moderna vaccine, 100% of people tested had antibodies to SARS-CoV-2. This is the longest duration reported in studies published to date. In a study of the Pfizer and Moderna vaccines, people who were vaccinated also had much higher levels of antibodies than those who had recovered from the infection.
Antibodies against the delta variant in 100% of people vaccinated
Better yet, a study in Israel showed that the Pfizer vaccine prevented 90% of infections after the two doses – it was also effective on the newer variants. And the reduction in infections means people are less likely to pass the virus on to those around them. For those who have been infected with the corona virus in the past, there is still a huge benefit to getting vaccinated. A study with the original COVID-19 virus showed that post-infection vaccination produced almost 100 times more antibodies than infection alone, and 100% of people vaccinated after infection had protective antibodies against the delta variant . COVID-19 vaccines may not be perfect, but they produce stronger antibody and T cell responses that provide a safer and more reliable means of protection than natural immunity, especially against newer variants. .
Author Jennifer T. Grier, University of South Carolina