Moderna is trialing an Omicron booster that combines its original COVID-19 vaccine with one targeting the highly contagious and now-dominant Omicron variant.
It hopes to have data from those trials available by June, with the goal of releasing the booster in Fall 2022.
COVID-19 variants: As a virus spreads, its genetic code can mutate, leading to new variants. Most variants die out quickly, but if a set of mutations helps the virus — by becoming more contagious or dodging immunity — that variant can take over.
The COVID-19 variant dominating today, Omicron, is heavily mutated compared to the strain that dominated when Moderna’s initial vaccine trials took place in 2020. And, unfortunately, all of the original shots, based on the strain that first emerged in Wuhan, are less effective against this version.
Combined with waning immunity against any versions of the coronavirus, some experts believe people will need to get regular booster shots to be protected against COVID-19.
An Omicron booster: Rather than continue to use the original vaccine for boosters, Moderna is trialing several different options, and its leading candidate is a “bivalent” booster that targets both the original version of the coronavirus and the Omicron variant.
This is similar to the annual flu shot, which is updated every year to target current strains of three or four flu viruses.
“The virus is evolving; our vaccines should evolve as well,” David Dowdy, an epidemiologist at Johns Hopkins University, told Financial Times. “The beauty of a bivalent vaccine would be that it keeps a product that we know works and adds a product that is tailored to the current virus.”
“We think it will be the bivalent Omicron-containing booster for this year.”Stephen Hoge
Data from an earlier trial of a bivalent vaccine, which targeted the original strain and the Beta variant, found that the antibodies produced by the bivalent booster worked better against all variants, including Omicron, for up to 6 months, compared to a standard booster.
Moderna says this is an encouraging sign that bivalent shots are superior to boosting against the original strain, and they expect that more targeted shots will produce longer-lasting immunity.
Looking ahead: Moderna’s Omicron booster is currently being evaluated in phase 2/3 trials. The company expects to have data from those trials by June, with the goal of having the booster approved for use in the fall.
“We think it will be the bivalent Omicron-containing booster for this year,” Stephen Hoge, Moderna’s president, said during a May 4 earnings call. “For 2023 plus, we would expect to continue to update the bivalent platform to reflect the then-dominant or then-at risk circulating strains of the variant.”
The big picture: Even if Moderna’s Omicron booster is available this fall, it’s not clear whether people will get it.
The existing vaccine might not be as effective at preventing a COVID-19 infection now that the Omicron variant is dominant, but people who received the original two-dose regimen plus a standard booster still have pretty good protection against severe infection and hospitalization.
People who aren’t at high risk of a severe outcome might feel that their current level of protection is enough — as of May 2022, just 45% of fully vaccinated adults have gotten a third shot, suggesting that there isn’t an overwhelming demand for more doses.
However, the demand may rise again if the virus mutates to become more virulent, or if the new vaccines work a lot better than the existing boosters.
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