The December 3 letter reports that participants in the study retained high levels of neutralizing antibodies through 119 days following first vaccination (90 days following the second vaccination). The results were consistent across all age cohorts (18-55, 56-70, and 71 and older) and despite a slight expected decline in titers of binding and neutralizing antibodies, mRNA-1273 has the potential to provide durable humoral immunity, according to the researchers.

Additionally, no serious adverse events were noted in the trial, no prespecified trial-halting rules were met, and no new adverse events that were considered to be related to the vaccine occurred after day 57, according to the researchers.

Moderna reaffirmed it expects to have approximately 20 million doses available in the U.S. by the end of the year and between 100 million and 125 million doses available globally in the first quarter of 2021. Of those 2021 doses, 85-100 million will be available in the U.S. and 15-25 million will be available outside the U.S.

In other Moderna news, the firm announced an expanded supply agreement with the Ministry of Health of Israel for an additional 4 million doses of mRNA-1273. The Israeli government has now secured 6 million doses of the vaccine and will support the ongoing efforts by the ministry to secure early access to a COVID-19 vaccine. Moderna has already initiated the rolling regulatory review process with the Ministry of Health in Israel, the firm said.