Episodes of SARS-CoV-2 infection among previously naturally infected or vaccinated individuals are already a global phenomenon that has created an important problem in understanding human immunity to viruses and vaccines.
The incidence of re-infection has been on the rise since the Omicron variant of SARS-CoV-2 spread in November 2021.
On March 12, 2020, the first case of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was diagnosed at Rio Grande do Norte in northeastern Brazil; After that, the pattern of COVID-19 followed several waves found elsewhere.
These waves were mostly caused by mutations in the SARS-CoV-2 virus, which led to the emergence of the dangerous subtype (VoC).
The dynamics of the protective immune response against SARS-CoV-2 has become difficult to understand due to the introduction of new VoCs into the population after previous SARS-CoV-2 infections or vaccinations.
The aim of the study was to look at the outbreak of SARS-CoV-2 re-infection that occurred in mid-January 2022 in Rio Grande do Norte, Brazil, after the Omicron variant was detected.
Between March 2020 and mid-February 2022, 58,097 out of a total of 172,965 people tested positive for SARS-CoV-2 with mild to severe respiratory symptoms.
Two positive RT-qPCR confirmations within 90 days of each other, clinical signs such as COVID-19, positive viral culture, and further viral RNA sequencing from both episodes that show individual strains were all required for a SARS-CoV-2 re-infection.
Of the 444 people who had been previously infected, they had a second SARS-CoV-2 infection, and 9 were selected for sequencing in this re-infection.
Three participants received a booster, and after giving a third / additional dose, they produced remarkable COVID-19, just like those who received two doses and had a history of Covid 19.
Genomic analysis has shown that there are differences in virus lineage between primary and re-infection, the latter being caused by the Omicron (BA.1) variant in fully vaccinated individuals.
After confirming that all subjects were previously SARS-CoV-2 infected and fully vaccinated, the results indicate that Omicron variant avoids natural and vaccine-induced immunity, reducing infection and ensuring the ongoing need for effective blocking vaccine development.
This highlights the need for more effective vaccines that have the potential to reduce infection and provide a long-lasting immune response.
The authors of the study concluded: “Our data suggest that the Omicron variant avoids the immunosuppression provided by natural transmission from any other SARS-CoV-2 variant or from a variety of vaccines.”
The results of the study were published on the printprint server medrixv.org.
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* Important information: Since medRxiv reveals preliminary scientific research that has not been peer-reviewed, they should not be considered final, should not be used for clinical practice / health-related behaviors, and should not be viewed as established data.