A look at the next stage in the battle against COVID-19: bivalent vaccines




The Canadian Press



Published Thursday, July 7, 2022 5:36AM EDT





Last Updated Thursday, July 7, 2022 5:36AM EDT

Predictions of a fall COVID-19 wave make another booster vaccine campaign likely but questions abound over how the virus will continue to evolve and what protections a new shot could offer.

Several vaccine manufacturers are racing to develop formulas that take into account the more infectious Omicron variant now driving cases, while policymakers are laying the groundwork for another large-scale vaccine blitz.

Much of this hinges on expectations that a so-called bivalent shot can blunt a potential future surge as flu season sets in, and alleviate pressure on a strained health-care system.

Currently available COVID-19 vaccines are monovalent, meaning they are tailored solely to the original novel coronavirus.

The proposed bivalent vaccines target specific mutations in the spike protein seen in both the old strain and newer Omicron strain, which itself has spawned several more infectious subvariants dominating infections today.

Last week, the National Advisory Committee on Immunization released interim guidelines for a fall program it said was most important for older adults and those at increased risk of severe COVID-19.

It also noted that while vaccine protection against symptomatic disease wanes over time, protection against severe disease is better maintained.

In the United States, advisers to the Food and Drug Administration said last week that fall boosters should contain some version of the Omicron variant.

NACI stopped short of urging a specific formulation while it awaited more evidence, but did say a bivalent shot could encourage uptake in the fall.

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