Washington - US January 23 ANI In view of the spike in COVID 19 infections globally, a recent study shed light on the strength, durability and breadth of neutralizing antibody responses generated by breakthrough infections in individuals vaccinated against SARS-CoV-2.
The findings were published in 'Cell', one of the scientific journals of Cell Press.
The project was led by Alexandra Walls and David Veesler in the Department of Biochemistry at the University of Washington in Seattle.
Even in non-immunologically naive individuals, the delta and Omicron coronaviruses variants of concern included enhanced transmissibility and immune evasion, compared to the ancestral pandemic coronaviruses.
These characteristics, along with the waning of immunity from vaccines, have led to breakthrough infections in vaccinated individuals. For the most part, healthy people who were vaccinated against the SARS-CoV- 2 usually did not have severe symptoms if they did contract the virus.
The researchers wanted to understand what effect catching the virus had on neutralizing antibodies, and to see how durable and broad these responses were. They hoped that advancing the knowledge would help guide vaccine policies and pandemic mitigation strategies.
The researchers learned that the degree of antibody response depended on whether a person had had one, two, three or four exposures to the spike protein through infection, vaccination or a combination of the two. The scientists also examined antibody responses in groups of people who had been vaccinated after having COVID - 19, those who had previously been vaccinated and had had a breakthrough infection, those who were only vaccinated, and those who were boosted and thus vaccinated three times.
Among the study subjects were those who had completed a three-vaccination protocol, those who had been vaccinated after recovering from COVID-19, and those with a breakthrough infection after vaccination launched almost identical neutralizing antibody responses, in terms of magnitude and breadth. Their antibody binding and antibody neutralizing responses to the spike protein in the current pandemic coronaviruses variants were much more potent and lasting than those generated by people who had received only two doses of COVID 19 vaccine or had a previous infection not followed by vaccination.
This observation suggested that the increased number of exposures to SARS-CoV-2 antigens, whether through infection and vaccination or triple vaccination, improved the quality of antibody responses.
The researchers looked at how broad the elicited antibodies could be. They investigated neutralization of the divergent Omicron SARS-CoV-2 variant of concern, which is currently responsible for the majority of cases in the United States. Their findings showed that boosted individuals or those who have a mixture of infection and double vaccination have neutralizing antibodies at similar levels to those that have been vaccinated twice against the original ancestral strain. This suggests there is a large amount of immune evasion, but that vaccine boosters could help close the neutralizing antibody gap caused by Omicron.
A similar pattern was found outside the family SARS-CoV -- 2, where repeated exposures improved the otherwise weak neutralizing antibody response to SARS-CoV. The authors did not identify improvements in antibody binding to common cold causing coronaviruses spike proteins like OC 43 or HKU 1.
This suggests that repeated SARS-CoV-2 exposure does not improve spike reactivity to more divergent coronaviruses. These findings supported the development of broader sarbecoviruses or coronavirus vaccines to be prepared for a future spillover event.