Severity of Omicron BA.4 / BA.5 strains in South African population

In a recent study posted on Research Square* Preprint server, researchers evaluated the clinical severity of the coronavirus 2 (SARS-CoV-2) omicron variant of severe acute respiratory syndrome.

Background

The South African Genome Surveillance Network (NGS-SA) detected the new SARS-CoV-2 Omicron BA.4 strain in January 2022 and BA.5 in February 2022. These strains were responsible for the emergence of the fifth wave of SARS. -CoV-2 infection. Various studies have estimated that BA.4 and BA.5 strains grow faster than BA.2. In addition, compared to the BA.1 and BA.2 strains, these BA.4 and BA.5 reduced serological neutralization in individuals who received three doses of the Coronavirus Disease 2019 (COVID-19) vaccine. I know it will let you.

About research

In this study, researchers evaluated the severity of infections caused by the SARS-CoV-2 Omicron BA.4 and BA.5 strains.

The team conducts data linkage studies and monitors national COVID-19 case data, SARS-CoV-2 laboratory data, and data related to COVID hospitalization from an active monitoring system called DATCOV at the national individual level. I got the information. -In South Africa-19. The dataset was limited to tests performed using the TaqPath ™ COVID-19 assay.

The team took advantage of the combination of the absence of the SARS-CoV-2 spike (S) gene and the result of S gene targeting disorder (SGTF) or S gene targeting positive (SGTP) due to the presence of the S gene. Circular variants discovered via genomic surveillance or for a set period of time depending on the lineage. SGTPCOVID-19 infections observed between October and November 2021 are classified as delta infections, between February and April 2022 they are classified as BA.2 infections, and from November 2022 to 1 SGTFCOVID-19 infections diagnosed during the month were classified as BA. One infectious disease, and the infectious disease discovered in April 2022, was classified as a BA.4 or BA.5 infectious disease.

The team compares BA.4, BA.5, and Delta infections with BA.1 infections to assess risk factors for COVID-19-related hospitalization and serious illness in patients hospitalized for COVID-19. Did. The analysis was performed by controlling factors related to hospitalization and severity.

result

The findings showed that a total of 884,379 COVID-19 cases were detected between October 1, 2021 and April 26, 2022. Of these, 16.3% were diagnosed with the TaqPath COVID-19 test. In addition, the team found that SARS-CoV-2 delta variants caused 1.3% of infections, BA.1 caused 76.6%, BA.2 caused 20.3%, and caused BA, based on the presence or absence of the S gene. I observed that. 4 or BA.5 caused 1.8% of infections.

In adults over the age of 25, 76.2% of all cases had delta infection, 81.6% had BA.1, 66.5% had BA.2, and 78.7% had BA.4 or BA.5. In children aged 5 to 18 years, 24.7% of all cases had BA.1 infection, 14.5% had Delta, 9.1% had BA.1, and 13.2% had BA.4 or BA.5.

Of the COVID-19 patients who required hospitalization, 13.5% were diagnosed with delta infection, 4.0% with BA.1, 3.3% with BA.2, and 4.8% with BA.4 or BA.5 infection. .. In addition, the number of reinfections detected was 9.7% for BA.1, 9.3% for BA.2, and 11.7% for BA.4 or BA.5 patients, compared to 2.9% for Delta patients.

Of the SARS-CoV-2 infected patients with known infectious variants or strains, 3.9% were hospitalized. In addition, of patients with known disease outcomes, 33.4% develop severe COVID-19 infection, of which 57.7% are Delta, 33.7% are BA.1, 26.2% are BA.2, and 27.5% are BA. He was a .4 or BA.5 patient.

Multivariate analysis showed that the probability of developing severe disease was higher in Delta, lower in BA.2, and comparable in BA.4 or BA.5 infections compared to BA.1 infections. .. In addition, individuals aged 40-59 and 60 years and older were more likely to develop severe illness than patients aged 19-24 years. In particular, the probability of developing severe illness was lower in women and individuals who received one or more COVID-19 vaccinations.

Overall, the findings show that patients infected with the SARS-CoV-2 Omicron BA.4 or BA.5 strain are at risk of developing the same serious illness and hospitalization as those infected with BA.1. I did. Researchers believe that this study may help in planning medical resources and developing vaccination policies.

*Important Notices

Research Square publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information. ..