Moderna is testing an Omicron-specific COVID vaccine. Here’s how it’s faring.

Moderna is testing an Omicron-specific COVID vaccine. Here’s how it’s faring. thumbnail

Omicron spread like wildfire in the winter of 2022, and vaccine maker Moderna is taking steps to prevent another resurgence. The results from an Omicron-specific booster trial were announced by the pharmaceutical giant. That mRNA vaccine produced a higher antibody response against multiple variants of SARS-CoV-2, the virus that causes a COVID-19 infection, than the vaccines already available.

The new booster is a bivalent vaccine. It creates an immune reaction against both the original virus as well as its variant. In this case, it contains the mRNA vaccine Spikevax, which the Food and Drug Administration approved for people 18 and older in January, plus a vaccine candidate that specifically targets Omicron.

Omicron has the most infective coronavirus variant. It has 37 mutations on its spike protein–the protein used by the virus to penetrate and enter cells–which is more than the Alpha and Delta variants. This hides the virus and allows it to be ignored by vaccine-induced or naturally acquired antibodies. Omicron’s success in evading the immune system led to a surge of reinfections in people who previously recovered from COVID-19 infections, and it caused breakthrough infections in fully vaccinated individuals. The variant was also behind an unprecedented number of hospitalizations in children between the ages of 5 to 11.

[Related: Moderna’s latest COVID vaccine trial for kids offers ‘really good news’]

In Moderna’s phase 2/3 clinical study, researchers discovered that patients who received Omicron-specific booster vaccine had higher neutralizing antibody reactions after a month than patients who received one dose of Spikevax vaccine. The Omicron-specific booster provided greater protection against other variants of concern such as Alpha, Beta, Gamma and Delta. The booster shot was well-tolerated among 437 study participants with no new side effects.

While the results are encouraging, more research is needed to determine how antibody responses translate into clinical outcomes. Also, how long the immune response lasts. Peter Jay Hotez, an infectious disease expert at Baylor College of Medicine wrote on Twitter he worried whether this shot will protect against other emerging variants: “My concern on this new bivalent booster is whether it really offers much advantage, given omicron is already behind us.” Hotez added that there was “no evidence” this vaccine offers better protection against BA.2 subvariants, which are more infectious versions of Omicron with mutations that make it harder to detect on a PCR test than Delta or the original Omicron strain.

Paul Burton, Moderna’s chief medical officer, predicts that the high antibody response could provide protection for at least a year, raising the possibility of annual boosters, according to NPR. Moderna will submit additional research data over the next few weeks. The new booster should be available by the end of the summer, subject to FDA approval.

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