Researchers examined the effectiveness of the bivalent coronavirus disease 2019 (COVID-19) vaccine against symptomatic infection with numerous SARS-CoV-2 variants that are circulating across the U.S. in a recent issue of the CDC’s Morbidity and Mortality Weekly Report.
Omicron versions of SARS-CoV-2
Several SARS-CoV-2 variant strains have evolved since the wild-type strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared towards the end of 2019, sparking the COVID-19 pandemic. In late 2021, for instance, the SARS-CoV-2 Omicron strain was discovered in those two countries.
Subvariant strains of the Omicron variant have since emerged via mutation and selection, the most recent of which are XBB and XBB.1.5. While XBB.1.15 was first reported in the United States in late December 2022, by early 2023, it had become the predominate spreading strain of SARS-CoV-2, with more than 50% of analyzed samples came back positive for this variant. XBB.1.15 had been detected in the United States in August 2022.
Description of the Research
Several COVID-19 vaccines have been created and given to individuals all over the globe in an attempt to reduce the global spread of SARS-CoV-2. The current COVID-19 vaccines are less effective against infection with some SARS-CoV-2 variants due to the introduction of mutant SARS-CoV-2 variants. Therefore, scientists have modified the original COVID-19 vaccines, which were developed to combat the wild-type strain of SARS-CoV-2, by adding components of the SARS-CoV-2 Omicron variant’s genetic material.
In this investigation, the VE of the revised Pfizer-BioNTech bivalent messenger ribonucleic acid (mRNA) COVID-19 vaccine was evaluated against symptomatic infection due to Omicron BA.5, XBB, and XBB.1.5 in immunocompetent individuals. Growth of the SARS-CoV-2 spike gene (S-gene) was inhibited or failed in real-time RT-PCR for BA.5, while the presence of the S-gene target was necessary for confirming infection in XBB/XBB.1.15 (SGTP).
A growing hegemony for XBB.1.5
Of the 29,175 nucleic acid amplification tests (NAATs) collected, 8,358 were from individuals who had additionally received a bivalent booster dose of COVID-19 between two and three months before their NAAT.
At the time of their NAAT, all of the participants in this research reported experiencing at least one symptom that was consistent with COVID-19. Overall, 47% of the study population was SARS-CoV-2 positive, with the vast majority (78%) infected with the BA.5 subvariant and the remaining (22%) with the XBB/XBB.1.5 variant.
There were 33 percent XBB.1.5 SARS-CoV-2 positive samples and above 50 percent XBB/XBB.1.5 samples between December 1, 2022 and January 2, 2023. When the researchers broke this 30-day period down into shorter periods, they discovered that the frequency of XBB.1.5 rose from 33% to 38% during December 11 to January 2, and from 43% to 43% between December 18, 2022 and January 2, 2023.
Symptomatic infection may be prevented by using a bivalent messenger RNA vaccination.
Of individuals who tested negative for SARS-CoV-2, around 34% had previously gotten a bivalent COVID-19 mRNA booster vaccination dose, whereas only 8% of those who tested positive had received the vaccine. In SARS-CoV-2 seropositives, the bivalent vaccine’s VE was comparable against BA.5 and XBB/XBB.1.15 infections.
Among people aged 18–49, the bivalent COVID-19 mRNA vaccine reduced the risk of developing symptoms by 52%; among those aged 50–64, the vaccine reduced the risk by 43%; and among those aged 65 and beyond, it reduced the risk by 37%. Most notably, among those who had received 2, 3, or 4 doses of the initial monovalent COVID-19 vaccine, this VE still appeared strong three months following immunization.
The results of this research provide credence to the Centers for Disease Control and Prevention’s (CDC’s) current recommendation that bivalent vaccine be made available to the public. Public health experts must keep an eye on the VE of both the monovalent and bivalent COVID-19 vaccinations when new SARS-CoV-2 variants develop.