'Cocktail' vaccines could offer increased protection against future COVID-19 variants of concern

'Cocktail' vaccines could offer increased protection against future Covid variants of concern
Antigenic map of SARS-CoV-2 variants constructed from single exposure convalescent and double vaccinated sera. Virus variants are shown as colored circles, sera as open squares with the color corresponding to the infecting variant. Triangles indicate sera positioned outside the central map area and point in the direction where the corresponding serum is positioned. Vaccine sera are shown in gray tones (from dark to light: mRNA-1273/mRNA-1273 n = 10, BNT162b2/BNT162b2 (BNT/BNT) n = 11, ChAdOx-S1/BNT162b2 (AZ/BNT) n = 10, ChAdOx-S1/ChAdOx-S1 (AZ/AZ) n = 10). The alpha + E484K variant is shown as smaller circle due to its additional substitution compared to the alpha variant. The x- and y-axis represent antigenic distances with one grid square corresponding to one two-fold serum dilution of the neutralization titer. The map orientation within x- and y-axis is free as only relative distances can be inferred.. Only single-variant exposure sera have been used for construction of the map. n = 2 beta convalescent and n = 6 BA.1 convalescent samples could not be positioned in the map because of too many <LOD titers. The table in the right part indicates how many sera from each group were positioned on the map (Ancestral virus conv. n = 10, Alpha conv. n = 10, Beta conv. n = 6, Delta conv. n = 7, BA.1 omicron conv. n = 12, BA.2 omicron conv. n = 12). Each of these serum samples has been titrated against D614G, alpha, alpha E484K, beta, gamma, delta, BA.1 omicron, BA.2 omicron, and BA.5 omicron variants. Credit: Nature Communications (2022). DOI: 10.1038/s41467-022-35312-3

COVID-19 vaccinations that combine two or more distinct variants of the SARS-CoV-2 virus could offer protection against both current and future "variants of concern," say scientists at the University of Cambridge and Medical University of Innsbruck.

In research published in Nature Communications, scientists show that the omicron variant of the virus is immunologically distinct from other variants such as the variant and the alpha and delta variants—that is, exposure to it has a different effect on the neutralizing antibody response and hence protection to other variants. But also, sub-variants of omicron are themselves distinct from each other. Their research further suggests that a combination of infection plus vaccination could provide increased protection against future variants.

Since SARS-CoV-2 was first identified in 2020, new variants of the virus have emerged as its genetic code evolves. Some of these variants threaten to spread faster, be more virulent or evade the protection of the vaccine—these are known as 'variants of concern."

Antonia Netzl, a Ph.D. student at Trinity Hall, Cambridge, together with colleagues at Cambridge and Innsbruck, analyzed data on people's immune responses to different variants and vaccinations. They used these to create "antigenic maps" and "antibody landscapes" to explore the differences between variants.

A more recent variant of concern is the omicron variant, but since its emergence in December 2021 several sub-lineages have evolved, including BA.1, BA.2, BA.4, BA.5, and BA.2.12.1. Of these, BA.5 became the dominant variant in many countries earlier this year, though new dominant variants have subsequently supplanted it.

Netzl and colleagues found, using their maps, that not only was omicron immunologically distinct from alpha and delta, but its sub-variants BA.1, BA.2 and BA.5 were also distinct from each other. The antibody landscapes, an illustration of people's immune profile, allowed the researchers to see how vaccination and/or infection with another variant increased virus neutralization against other viruses.

Netzl, a Gates Cambridge Scholar, said, "We found that people who had been exposed to BA.1 were better protected against BA.2, but the reverse wasn't true.

"But the good news was that we also found that two distinct exposures—for example, vaccination plus infection with a different variant—increased antibody levels against all variants. So, people who had been vaccinated and then infected with delta, for example, were better protected against omicron than those who had only been vaccinated or infected and not both."

Netzl says this suggests that an update of the vaccine variant will be beneficial for increasing antibody levels and thereby offering some protection against all currently circulating variants as well as yet-unknown variants.

"Our work suggests that an update of the vaccine variant will be beneficial for increasing antibody levels and thereby protection against all currently circulating variants. The bivalent vaccines, which contain the original prototype variant and an omicron in a single vaccine dose, could provide this increased protection."

The findings are supported by clinical trials and have already been put into practice with the roll-out of the bivalent Prototype+omicron BA.4/5 and Prototype+ BA.1 vaccines.

Although infection by multiple different variants gives the unvaccinated protection too, Netzl points out that vaccinations offer effective protection and reduce the severity of infection.

"People should still make sure they get themselves vaccinated, even if they have already had COVID once. Vaccination is important for boosting our and thereby reducing the risk of infection and symptom severity."

Netzl said the research, alongside the real-world , gives a strong basis to the investigations in development and design.

More information: Annika Rössler et al, BA.2 and BA.5 omicron differ immunologically from both BA.1 omicron and pre-omicron variants, Nature Communications (2022). DOI: 10.1038/s41467-022-35312-3

Journal information: Nature Communications
Citation: 'Cocktail' vaccines could offer increased protection against future COVID-19 variants of concern (2022, December 14) retrieved 18 June 2024 from https://medicalxpress.com/news/2022-12-cocktail-vaccines-future-covid-variants.html
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