Omicron-targeted COVID vaccine gets approval: From efficacy to dosage, all you need to know

Late last year, the Omicron COVID variant was first spotted in South Africa and within months, it became the dominant coronavirus strain the world over. And with that, the pattern of virus spread significantly changed as new subvariants cropped up every few months. Owing to this, the experts have been working on an  Omicron-specific vaccine that became a reality recently with Moderna Inc. receiving approval from the UK government for a Covid-19 booster shot that targets omicron. The snappily-named Spikevax Bivalent Original/Omicron has been given the green light for use in the UK and is expected to be rolled out in other countries soon. Here’s all you need to know:

What is special about this vaccine?

The new shot targets two separate strains of Covid-19 — the original version of the virus that emerged in the central Chinese city of Wuhan along with the BA.1 subvariant, the earliest version of omicron. Other versions of omicron, BA.4 and BA.5, are now more prevalent, but the virus is evolving faster than new vaccines can be formulated and tested, and this is the closest match available that has received clearance. Moderna has another shot available that targets the BA.4 and BA.5 subvariants, which has been ordered by the US, but not yet cleared.

How effective is it?

Moderna says the drug triggered a strong immune response against the original virus and BA.1 subvariant. It also generated a good immune response against omicron’s latest subvariants BA.4 and BA.5., according to the UK government. However, these are findings from laboratory studies that look at levels of disease-fighting antibodies, which is just a proxy for protection in the real world. 

Who is currently eligible for the bivalent booster?

The bivalent shot has been approved for use as a booster in adults only. So far, it’s only approved in the UK, where it could play a role in the fall booster campaign when people aged over 50 or with weakened immunity will be offered another shot. Still, British health officials said people should take any booster offered to them, as existing shots continue to provide excellent protection against severe disease and death.

How often will you need to get the shot?

It’s not clear yet how often boosters — bivalent or otherwise — are needed, but experts see annual top-ups for vulnerable people as plausible because Covid immunity wanes over time and the emergence of new variants is inevitable. It’s reasonable to expect that Covid shots could be given on a similar annual schedule like the vaccine against the flu, which also changes constantly.

What isn’t clear is whether shots will need continual updating, as the original vaccines produced at the height of the pandemic still provide defense against severe disease and death.

How safe is the omicron-targeting booster?

Moderna says the shot’s safety profile is similar its original Covid vaccine.

(With inputs from agencies)