By IDSE News Staff

The Moderna messenger RNA (mRNA) vaccine against COVID-19 appears to be effective against the variant virus strains, including the new Delta variant first identified in India. However, the efficacy is less than against the original SARS-CoV-2. 

The company conducted in vitro neutralization studies of sera from individuals vaccinated with its COVID-19 vaccine, which showed that the vaccine produced neutralizing titers against all variants tested, including additional versions of the Beta variant (B.1.351, first identified in South Africa), three lineage variants of B.1.617 (first identified in India), including the Kappa (B.1.617.1) and Delta variants (B.1.617.2); the Eta variant (B.1.525, first identified in Nigeria); and the A.23.1 and A.VOI.V2 variants first identified in Uganda and Angola, respectively (bioRxiv 2021 Jun 28. doi: https://doi.org/10.1101/2021.06.28.449914).

The study methodology was described previously in the letter to the editor published in The New England Journal of Medicine on April 15 concerning the variants first identified in the United Kingdom (Alpha, B.1.1.7) and the Republic of South Africa (Beta, B.1.351) using serum samples from eight participants obtained one week after the participants’ second dose of the primary series in the phase 1 clinical trial of the Moderna COVID-19 vaccine.

These most recent data include neutralization assays against additional variant strains. This additional analysis showed minimal impact on neutralizing titers against the Alpha and A.23.1 variants relative to those against the ancestral strain (D614G). 

This analysis also showed a modest reduction in neutralizing titers against the Delta (2.1-fold), Gamma (P.1, 3.2-fold), Kappa (3.3- to 3.4-fold), and Eta (4.2-fold) variants relative to those against the ancestral strain.

Consistent with previous results, a 7.3- or 8.4-fold reduction in neutralizing titers was observed with the additional versions of the Beta variant relative to the ancestral strain. Additionally, an 8.0-fold reduction in neutralizing titers relative to the ancestral strain was observed for A.VOI.V2, the variant first identified in Angola, but currently not designated as a Variant of Concern or Interest.

Moderna is pursuing a clinical development strategy against emerging variants to proactively address the pandemic as the virus continues to evolve. The company is also studying mRNA-1273.211, a multivalent booster candidate that combines a 50-50 mix of mRNA-1273 and mRNA-1273.351 in a single vaccine at several dose levels in an ongoing study.

The mRNA vaccine against COVID-19 encodes for a prefusion stabilized form of the spike protein. 

“As we seek to defeat the pandemic, it is imperative that we are proactive as the virus evolves. We remain committed to studying emerging variants, generating data and sharing it as it becomes available. These new data are encouraging and reinforce our belief that the Moderna COVID-19 vaccine should remain protective against newly detected variants,” said Stéphane Bancel, the CEO of Moderna. “These findings highlight the importance of continuing to vaccinate populations with an effective primary series vaccine.”