In a recent Report published by the United States Centers for Disease Control and Prevention (CDC), researchers discuss the efficacy of the bivalent coronavirus disease 2019 (COVID-19) vaccine against symptomatic infection with several SARS-CoV-2 variants that are currently circulating throughout the U.S.
Study
In an effort to mitigate the spread of SARS-CoV-2, several COVID-19 vaccines have been developed and administrated to people around the world. Unfortunately, the emergence of mutated SARS-CoV-2 variants has reduced the efficacy of current COVID-19 vaccines against infection with certain variants. As a result, researchers have updated the original COVID-19 vaccines, which were previously targeted against the wild-type strain of SARS-CoV-2, to also incorporate the genetic material of the SARS-CoV-2 Omicron variant.
In the current study, the vaccine effectiveness (VE) of the updated Pfizer-BioNTech bivalent messenger ribonucleic acid (mRNA) COVID-19 vaccine was estimated against symptomatic infection caused by Omicron BA.5, XBB, and XBB.1.5 infections in immunocompetent adults. Whereas BA.5 infection was identified upon the reduction or failure of the SARS-CoV-2 spike gene (S-gene) amplification (SGTF) in real-time reverse transcription-polymerase chain reaction (RT-PCR), XBB/XBB.1.15 infection was confirmed by S-gene target presence (SGTP).
Increasing Dominance of XBB.1.5
A total of 29,175 nucleic acid amplification tests (NAATs) were obtained from adults who had previously received between two and four doses of the original COVID-19 vaccine dose, 8,358 of whom had also received a bivalent booster dose two to three months prior to their NAAT.
All adults who participated in the current study had reported one or more COVID-19-like symptoms at the time of their NAAT. Taken together, 47% of the study participants tested positive for SARS-CoV-2, 78% and 22% of whom were infected with BA.5 or XBB/XBB.1.5 subvariants, respectively.
Between December 1, 2022, and January 2, 2023, 33% of the samples that tested positive for SARS-CoV-2 were of the XBB.1.5 lineage, with over 50% accounting for XBB/XBB.1.5. However, when this 30-day period was separated into shorter intervals, the researchers found that XBB.1.5 prevalence increased from 33% to 38% between December 11-January 2, and 43% between December 18, 2022, and January 2, 2023.
Bivalent mRNA Vaccine Protects against Symptomatic Infection
About 34% of patients who tested negative for SARS-CoV-2 had previously received a bivalent COVID-19 mRNA booster vaccine dose as compared to those who tested positive. Of those who tested positive for SARS-CoV-2, the VE of the bivalent vaccine was similar against BA.5 and XBB/XBB.1.15 infections.
When considering age, the bivalent COVID-19 mRNA vaccine was 52% effective against symptomatic infection in adults between 18 and 49 years of age, 43% effective in those aged 50-64, and 37% effective in those over the age of 65. Notably, this VE did not appear to wane three months after vaccination in individuals who had previously received two, three, or four doses of the original monovalent COVID-19 vaccine.
Conclusion
The current study finding support current recommendations by the United States CDC to continue to provide 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.
Source:
https://www.news-medical.net/news/20230125/Updated-bivalent-mRNA-booster-protects-against-circulating-SARS-CoV-2-variants.aspx