lately Weekly report of morbidity and mortality Published by the US Centers for Disease Control and Prevention (CDC), researchers discuss effectiveness Bivalent coronavirus disease 2019 (COVID-19) vaccine against accidental infection with several SARS-CoV-2 variants currently circulating throughout the United States
Stady: Early estimates of the efficacy of a dsRNA booster dose vaccine in preventing symptomatic SARS-CoV-2 infection are due to Omicron BA.5 and XBB/XBB.1.5 related sublines among immunocompetent adults—increasing community access to Testing Program, United States, December 2022 to January 2023. Image credit: PeopleImages.com – Yuri A / Shutterstock.com
SARS-CoV-2 Omicron sub-variants
Since the emergence of a wild-type strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the end of 2019, which subsequently led to the COVID-19 pandemic, several variant strains of SARS-CoV-2 have emerged. The SARS-CoV-2 Omicron variant, for example, was originally detected in Botswana and South Africa in late November 2021.
Since then, the Omicron variant has mutated into several variant strains, the most recent of which include XBB and XBB.1.5. In the United States, Omicron subvariant XBB was originally detected in August 2022; However, by late December 2022, XBB.1.15 had been identified as the dominant circulating strain of SARS-CoV-2, with over 50% of sequenced samples testing positive for this variant.
In an effort to mitigate the spread of SARS-CoV-2, several COVID-19 vaccines have been developed and administered to people around the world. Unfortunately, the emergence of mutant SARS-CoV-2 variants has reduced the effectiveness of current COVID-19 vaccines against infection with specific variants. As a result, the researchers updated the original COVID-19 vaccines, which previously targeted a wild-type strain of SARS-CoV-2, to also include the genetic material of the SARS-CoV-2 variant Omicron.
In the current study, the vaccine efficacy (VE) of an updated ribonucleic acid (mRNA) COVID-19 vaccine from Pfizer-BioNTech against adventitious infection caused by Omicron BA.5, XBB, and XBB.1.5 infections in immunocompetent adults was estimated. Whereas BA.5 infection was identified upon reduced or failed amplification of the SARS-CoV-2 S-gene (SGTF) in reverse transcription polymerase chain reaction (RT-PCR), XBB/XBB. Infection 1.15 was confirmed by targeted presence of the S (SGTP) gene.
Increased dominance of XBB.1.5
A total of 29,175 nucleic acid Amplification tests (NAATs) were obtained from adults who had previously received two to four doses of the original COVID-19 vaccine dose, and 8,358 of them also received a bivalent booster dose two to three months before the NAAT.
All adults who participated in the current study reported one or more symptoms similar to COVID-19 at the time of the NAAT. Taken together, 47% of the study participants tested positive for SARS-CoV-2, and 78% and 22% of them were infected with BA.5 or XBB/XBB.1.5 sub-variants, respectively.
Between December 1, 2022, and January 2, 2023, 33% of samples tested were positive for SARS-CoV-2 of the XBB.1.5 strain, with more than 50% accounting for XBB/XBB.1.5. However, when this 30-day period was separated into shorter time periods, the researchers found that the prevalence of XBB.1.5 increased from 33% to 38% between December 11 and January 2, and 43% between December 18, 2022, and January 2, 2023.
A bivalent mRNA vaccine protects against symptomatic infection
About 34% of patients who tested positive for SARS-CoV-2 had previously received a dose of the COVID-19 mRNA booster vaccine compared to those who tested positive. Among those who tested positive for SARS-CoV-2, the VE of the bivalent vaccine was similar to that of BA.5 and XBB/XBB.1.15 infection.
When considering age, the COVID-19 mRNA vaccine was 52% effective against symptomatic infection in adults ages 18 to 49, 43% effective in those ages 50 to 64, and 37% effective in those Those over 65 years of age. Notably, this vaccination did not fade three months after vaccination for individuals who had previously received two, three, or four doses of the original monovalent COVID-19 vaccine.
The current study finds support for current recommendations made by the Centers for Disease Control and Prevention in the United States to continue providing bivalent immunization to the public. As SARS-CoV-2 variants continue to emerge, it is increasingly important for public health officials to monitor the VE of both monovalent and bivalent COVID-19 vaccines.
- Link Gillis, R, Cesla, AA, Roper, LE, et al. (2022). Early estimates of the efficacy of a dsRNA booster dose vaccine in preventing symptomatic SARS-CoV-2 infection are due to Omicron BA.5 and XBB/XBB.1.5 related sublines among immunocompetent adults—increasing community access to Testing Program, United States, December 2022 to January 2023. Weekly report of morbidity and mortality. doi: 10.15585/mmwr.mm7205e1. https://www.cdc.gov/mmwr/volumes/72/wr/mm7205e1.htm