Moderna released new study results today showing a fivefold increase in neutralizing antibodies for its combination COVID-19 vaccine booster. The new booster in development contains the original mRNA-1273 (Spikevax) vaccine and one specifically designed to target the more recent BA.4 and BA.5 Omicron subvariants.
The announcement comes at a time when the proportion of BA.4 and BA.5 subvariants in the United States is growing. These two strains now account for about 35% of those circulating in the US, according to CDC data.
The combination vaccine also boosted neutralizing antibodies by more than sixfold among seronegative people in the study. In addition, neutralizing titers against BA.4 and BA.5 were approximately three times lower than previously reported neutralizing titers against BA.1.
Moderna submitted this data to the US Food and Drug Administration as part of a request to update the composition of their booster. The company anticipates initial shipments of this product, known as bivalent mRNA-1273.214, as early as this summer.
The phase 2/3 study shows that 1 month after administration in previously vaccinated and boosted people, a 50 µg booster dose of mRNA-1273.214 elicited “potent neutralizing antibody responses” against BA.4 and BA.5 in all participants regardless of prior infection, the company reported.
Today’s findings build on prior results released earlier this month showing superiority of mRNA-1273.214 compared to the original mRNA-1273 vaccine for neutralizing antibody geometric mean titers against Omicron BA.1.