A small study indicated that Moderna’s messenger RNA COVID-19 vaccine was effective against the Delta variant.
Using serum samples from eight Phase 1 participants drawn one week after administering the second dose of the vaccine, the analysis found a 2.1-fold reduction in neutralizing titers against the Delta (B.1.617.2) variant relative to the ancestral strain of the virus.
The World Health Organization has urged the public — including the fully vaccinated — to continue wearing masks and practice social distancing to reduce the spread of the Delta variant.
In related news, Moderna’s COVID-19 also won emergency use authorization in India, where scientists first identified the Delta variant.
The variant is gaining traction in the U.S. and will likely gain dominance in the coming weeks.
The vaccine appears to also offer protection against the Beta (B.1.351), Gamma (P.1), Kappa (B.1.617.1) and Eta (B.1.525) variants, although the reduction in neutralizing titers for those variants was greater than for the Delta variant.
The relative reduction in neutralizing titers was as follows:
- Gamma: 3.2-fold
- Kappa: 3.3–3.4-fold
- Eta: 4.2-fold
- Beta: 7.3–8.4-fold reduction
The results from the preprint study are posted on BioRxiv.
“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, Moderna CEO, in a statement. “These findings highlight the importance of continuing to vaccinate populations with an effective primary series vaccine.”
The company is also testing a booster candidate known as mRNA-1273.351 based on the Beta variant. Additionally, it is testing a multivalent booster known as mRNA-1273.211 that combines its currently authorized vaccine with mRNA-1273.351.