Is the Vaccine Developed For SARS-CoV-2 Omicron Variant Ready?
At the onset of the COVID-19 pandemic, the world had set out to engineer vaccines that perfectly matched the genetic code of the original SARS-CoV-2 virus to provide maximum immunity against the disease. However, with new and concerning variants and subvariants continuing to emerge and circulate, researchers are now starting to explore innovative approaches to design vaccines targeting novel versions of SARS-CoV-2 with slightly different genetic codes. Indeed, vaccine manufacturing companies including Pfizer, Moderna, and Novavax are currently working on developing novel vaccines and booster shots to improve immunity against the now-dominant Omicron variant. In fact, as of August 15, Moderna’s Spikevax bivalent Original/Omicron booster vaccine has been granted approval in the UK for adult booster doses by the Medicines and Healthcare products Regulatory Agency (MHRA) and is soon expected to be approved in other countries. Read along to learn more about the updated vaccine and alternative vaccine projects that are currently under development.
What are bivalent and multivalent vaccines?
As they exclusively target the original strain of the virus, the first generation of vaccines and boosters developed against SARS-CoV-2 have been monovalent. These vaccines have proved to be highly efficient in preventing severe disease and death linked to COVID-19. In fact, a recent study by Watson et al. (2022) estimates that monovalent vaccines and boosters have averted up to 20 million deaths around the world in their first year of use. However, the improved ability of the dominant Omicron variant to evade immunity induced by vaccines and prior infections has called for the development of Omicron-containing formulations including bivalent and multivalent vaccines. Accordingly, bivalent vaccines are engineered to elicit immune responses to two differing antigens. Accordingly, the second generation of COVID-19 vaccines and boosters including Moderna’s Spikevax bivalent Original/Omicron booster vaccine targets the BA.1 subvariant of the Omicron strain alongside the ancestral strain of SARS-CoV-2 by combining 25 micrograms of Moderna’s original COVID-19 vaccine and 25 micrograms of Omicron-targeting vaccine. Similarly, multivalent vaccines elicit an immune responses against more than two variants of a pathogen.
How effective is the bivalent vaccine?
In a pre-print study by Chalkias et al. (2022), the bivalent vaccine by Moderna (mRNA-1273.214 50-μg) has been observed to elicit a superior neutralizing antibody response against the Omicron strain, and an equivalent immune response against the original strain of SARS-CoV-2 compared to the monovalent Moderna COVID-19 vaccine (mRNA-1273 50-μg) containing exclusively the mRNA sequence associated with the original SARS-CoV-2. Moreover, unpublished data presented by Moderna has illustrated that antibody levels were observed to remain high for prolonged periods following the bivalent vaccine. While the data on the efficacy of the new vaccine against other variants remains scarce, an exploratory analysis of the bivalent vaccine has suggested that the bivalent vaccine could generate a substantial level of the immune response against the Omicron subvariants BA.4 and BA.5.
Is the bivalent vaccine safe?
Although there is currently no multivalent and only one bivalent vaccine approved for SARS-CoV-2, bivalent and multivalent vaccines are not new. Many non-COVID vaccines such as those targeting influenza and human papillomavirus virus (HPV) are commonly used in healthcare. With regards to the Spikevax bivalent Original/Omicron booster vaccine, Moderna has reported that the safety profile of the vaccine is similar to the original COVID-19 vaccine of the company. Indeed, evaluating the safety and reactogenicity of Moderna’s Spikevax bivalent Original/Omicron booster vaccine, Chalkias et al. (2022) have confirmed that its safety and reactogenicity profile resembled that of the original COVID-19 vaccine when performed as second booster doses. The study has found that adverse reactions following the administration of the second booster dose of the bivalent vaccine were equally or less frequent than those observed after the first booster dose of and the second primary dose of the original COVID-19 vaccine. Finally, it should also be mentioned that the vaccine has met the safety requirements of the Medicines and Healthcare products Regulatory Agency (MHRA) in the UK.
Are other Omicron-containing vaccines underway?
Moderna’s bivalent vaccine has been granted its first approval in the UK and is expected to shortly become available for use in many other countries and regions such as Canada, Australia, the EU, and the US. However, there are various vaccines under development that adopt different innovative approaches to adapt to the changing nature of SARS-CoV-2. For instance, Pfizer and BioNTech are working on other bivalent vaccines. In fact, Pfizer has recently reported data from animal studies of a booster containing Omicron subvariants BA.4 and BA.5. The findings have suggested that compared to those containing the ancestral strain and older strains of SARS-CoV-2, boosters with newer strains elicit higher levels of antibody response. There are also trials underway for a more universal, pan-COVID vaccine providing immunity against all coronaviruses regardless of variant or subvariant.
Alongside increasing options for vaccination, more and more diagnostic testing options to check for active infections or immunity levels are being developed and becoming available. Rapid antigen tests, including our RapidFor™ Antigen Rapid Test Kit, offer an accurate, convenient, and quick method to check for active infections with SARS-CoV-2. In the form of at-home tests, some rapid antigen tests also allow for self-administration wherever and whenever the need arises. Moreover, combination tests, such as our SARS-CoV-2 + Flu A/B + RSV Combo Rapid Test Kit, allow for the simultaneous detection and differentiation of infections with SARS-CoV-2 and other respiratory viruses with similar clinical presentations. Finally, rapid antibody tests, such as our RapidFor™ Rapid IgG/IgM Test Kit, can quickly detect the immunity level elicited by vaccination or previous infection.
Altogether, with the changing nature of SARS-CoV-2 and the changing needs of the world, our vaccines, diagnostic methods, and treatments keep adapting novel approaches to ensure maximum protection, accuracy, speed, accessibility, and comfort. The development and use of Omicron-containing vaccines, more effective viral treatments, along with more accurate, quick, convenient, and accessible testing options could have the extensive potential for public health and pandemic management. Although the COVID-19 pandemic is yet to be over, and the world continues to face novel challenges posed by other viruses such as monkeypox, these advances are highly promising for the future.
REFERENCES
Chalkias, S., Harper, C., Vrbicky, K., Walsh, S. R., Essink, B., Brosz, A., McGhee, N., Tomassini, J. E., Chen, X., Chang, Y., Sutherland, A., Montefiori, D. C., Girard, B., Edwards, D. K., Feng, J., Zhou, H., Baden, L. R., Miller, J. M., & Das, R. (2022). A Bivalent Omicron-containing Booster Vaccine Against Covid-19. medRxiv. https://doi.org/10.1101/2022.06.24.22276703
