COVID-19 Bivalent Boosters Bolster Protection

Key Takeaways

• Bivalent COVID-19 vaccine boosters offer added protection against currently circulating viral strains.
• Administration of the COVID-19 vaccine may become an annual recommendation, similar to influenza vaccination.

What questions come to mind when you ask yourself what you are doing to stay healthy? I think of: Do you eat vegetables? Do you exercise? Do you get an annual influenza vaccine? Have you received your COVID-19 vaccination series and the newest booster?

Now that a newly recommended COVID-19 bivalent booster is available, we all need to decide what the best decision is for vaccination to protect ourselves from COVID-19 infection. Almost 3 years into a pandemic—the first of this scale that most of us have ever witnessed—I have become accustomed to hearing various opinions, thoughts, and exasperations from patients and healthcare professionals alike. Some questions are about the virus itself, the United States government’s response to the pandemic, the healthcare community, or the ever-changing landscape of vaccine recommendations. How is anyone able to make a decision about which vaccine recommendations to follow?

I believe the best way to approach COVID-19 vaccination decisions is to follow the research, gather evidence, and educate yourself.

Why Do We Need a Bivalent Booster?
Throughout the viral life cycle, new variants emerge and evolve as mutations occur during viral RNA transcription and replication. The COVID-19 variants are routinely monitored through sequence-based surveillance. In late fall 2021, omicron replaced other circulating variants and became the predominant variant. This emergence of the omicron variant coincided with the availability of monovalent booster vaccinations for patients who had completed their primary series. Data from this period have shown that patients who received their primary vaccine series plus a monovalent booster had an 89% reduction in need for hospital admission within 2 months of the booster, but prevention of hospitalization decreased to 66% 4-5 months after receipt of the booster dose. Despite data on the effectiveness of booster dosing, immunity wanes after several months, and we still have many questions regarding frequency of dosing and variant-specific coverage in boosters.

The CDC recommends the bivalent booster for anyone aged 5 years or older who has completed a primary vaccination series. The bivalent vaccine contains ancestral Wuhan-Hu-1 mRNA for spike protein paired with omicron B.1.1.529 spike protein mRNAs and has been shown to induce strong neutralizing antibody responses to the omicron BA.1 variant. Recently published and presented research reported that the Moderna bivalent booster (mRNA1273.214) elicited neutralizing antibody responses against omicron that were superior to the prior authorized vaccine (mRNA-1273). In fact, this bivalent mRNA-1273.214 vaccine also elicited higher binding antibody responses against multiple other variants (alpha, beta, gamma, and delta) than the original mRNA-1273 vaccine.

Is the Bivalent Booster Effective?
In immunogenicity studies of more than 1200 adults (approximately 600 in the Pfizer study and 600 in the Moderna study) who had completed their primary vaccination series and received a monovalent booster, participants received either the same monovalent vaccine as a booster or a bivalent booster (ancestral strain and omicron BA.1). One month after the second booster dose, the geometric mean neutralizing antibody titer level and seroresponse rate against the BA.1 variant were higher with the bivalent vaccine vs the monovalent vaccine. In another study of more than 800 participants, it was found that a bivalent booster dose of mRNA-1273.214 increases immune response in those who have completed a primary series with a previous booster.

Initial study data have demonstrated that the newest bivalent boosters targeting the BA.4 and BA.5 subvariants are not much more effective than the original monovalent boosters. Larger trials of these bivalent boosters are ongoing. It remains to be seen whether the modestly increased immune response with the newest bivalent boosters translates to clinically relevant protection against COVID-19 infection.

Is the Bivalent Booster Safe?
The bivalent boosters were authorized based on clinical data with the monovalent product and results of randomized immunogenicity studies that compared bivalent formulations of the vaccines containing mRNA from the original and BA.1 omicron strains of SARS-CoV-2 with their respective monovalent formulations. Adverse events related to receipt of a bivalent booster were similar in severity and frequency to the monovalent products—albeit sometimes less so.

Moving Forward
Although the omicron variant has been shown to cause milder symptoms than earlier variants, likely due to its lower intrinsic virulence, this does not mean we should discount the value of boosters like the bivalent ones now available. Given the known effect of increased morbidity associated with COVID-19 infection, we should all consider updated vaccination as a reliable method of protection against COVID-19 infections and continue to support further research into effective prevention and treatment strategies.

Your Thoughts?
How do you discuss the bivalent booster and its importance with your patients? Join the discussion by posting a comment below.