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Merck and Moderna mRNA vaccine cuts melanoma recurrence 49%

8/20/2026

44 9 Full Breakdown

Summary

Story summary

Merck and Moderna reported their mRNA vaccine cut melanoma recurrence in a Phase 3 trial.
Interim data showed a 49% lower risk of recurrence or death after five years.
Distant metastasis risk fell 59% versus Keytruda alone.
Side effects matched typical vaccines, with no new safety signals.
The announcement drove Moderna’s shares up over 150% and Merck’s about 10%.

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Story summary

Merck and Moderna reported their mRNA vaccine cut melanoma recurrence in a Phase 3 trial.
Interim data showed a 49% lower risk of recurrence or death after five years.
Distant metastasis risk fell 59% versus Keytruda alone.
Side effects matched typical vaccines, with no new safety signals.
The announcement drove Moderna’s shares up over 150% and Merck’s about 10%.