Moderna’s booster vaccines increase neutralising antibodies against COVID-19 variants

Moderna has revealed initial data from a phase 2 study showing that a single dose of its approved vaccine or booster candidate increased neutralising antibodies against the original SARS-CoV-2 strain and two variants of concern.

A single dose of either the original mRNA-1273 vaccine or booster candidate mRNA-1273.351 increased neutralising antibody titres against the ancestral COVID-19 strain as well as the B.1.351 variant first discovered in South Africa and the P.1 variant first discovered in Brazil.

The variant-specific booster candidate – mRNA-1273.351 – encodes for the spike protein of the SARS-CoV-2 variant B.1.351.

In addition, the new results found that a booster dose of mRNA-1273.351 achieved higher neutralising antibody titres against the B.1.351 variant compared to another dose of mRNA-1273, the original vaccine formulation.

The data comes from an ongoing study which is testing three approaches to boosting protection in previously vaccinated participants, including a single dose of the mRNA-1273.351 candidate, a multi-valent booster candidate known as mRNA-1273.211 that combines Moderna’s original vaccine with mRNA-1273.351 in a single vaccine and a 50µg booster dose of mRNA-1273.

“We are encouraged by [this] new data, which reinforces our confidence that our booster strategy should be protective against these newly detected variants,” said Stéphane Bancel, chief executive officer of Moderna.

“The strong and rapid boost in titres to levels above primary vaccination also clearly demonstrates the ability of mRNA-1273 to induce immune memory,” he added.

Evaluation of additional samples collected at later time points after the booster, mRNA-1273.211, and a lower dose of mRNA-1273.351 are ongoing, with Moderna expecting data from these approaches ‘shortly’.

“Our mRNA platform allows for rapid design of vaccine candidates that incorporate key virus mutations, potentially allowing for faster development of future alternative variant-matched vaccines should they be needed. We look forward to sharing data on our multivalent booster candidate, mRNA-1273.211, which combines mRNA-1273 and mRNA-1273.351 in a single vaccine, when available,” said Bancel.