A recent study looked at the strength, durability and breadth of neutralizing antibody responses generated by breakthrough infections.
The findings are in Cell, a scientific journal. The University of Washington in Seattle has a Department of Biochemistry.
The Delta and Omicron coronaviruses have characteristics that are different from the ancestral pandemic coronaviruses.
The waning of immunity from vaccines has led to breakthrough infections in vaccine recipients. Most healthy people who are vaccined against the SARS-CoV-2 don't have much of a problem if they get the virus.
The researchers wanted to understand what effect catching the virus after being vaccined has on the immune system. Their hope is that this knowledge will help guide vaccine policies.
The researchers found that the degree of response depended on whether the person had one, two, three, or four exposure to the spike. The scientists looked at the responses of people who had been vaccined after having COVID-19, those who had been previously vaccined, those who were only vaccined, and those who had been boosted.
The study subjects who had completed a three-vaccine protocol, and those who had been injected after recovering from COVID-19, launched almost comparable neutralizing antibody responses, in terms of magnitude and breadth. People who had received only two doses of COVID-19 vaccine or who had a previous infection not followed by a vaccine were more likely to have potent and lasting responses to the spike protein in the current coronaviruses variant.
The observation suggested that the increased number of exposures to the SARS-CoV-2 antigens, either through infection and vaccination or triple vaccination, enhanced the quality of the antibody responses.
The researchers looked at how broad the elicited antibodies could be. The majority of cases in the United States are caused by the Omicron SARS-CoV-2 variant of concern. Their findings showed that boosted individuals with a mixture of infections and double vaccinations have the same levels of neutralizing antibodies as subjects who have not been exposed to the original strain. This suggests a large amount of immune evasion, but that vaccine boosters can help close the gap caused by Omicron.
Outside of the SARS-CoV-2 family there is a pattern where repeated and multiple exposures improve the neutralizing effect of the virus. The authors did not find any improvements in the binding of the antibody to the coronaviruses. This suggests that exposure to more coronaviruses does not improve spike reactivity. In the event of a future spillover event, these findings support the development of sarbecoviruses or coronaviruses vaccines.
The study groups were made up of people from the Hospitalized or Ambulatory Adults with Respiratory Viral Infections project at the University of Washington in Seattle. Helen Chu, an infectious disease physician at the University of Washington Medicine, leads HAARVI, which looks at recovered COVID-19 patients to study immune responses over time, to understand the long-term consequences of the infection, and to compare immune responses from vaccines and natural infections.
Researchers from the Department of Medicine and the Department of Laboratory Medicine and Pathology at the University of Wisconsin School of Medicine helped conduct the study.
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