What is the difference between Spikevax and mNexspike by Moderna?

Spikevax and mNexspike are both mRNA vaccines targeting the same strain of COVID-19. Spikevax is the original vaccine now licensed down to age 6 months. The mNexspike product is a newer mRNA vaccine licensed for ages 12 years and older with an advanced design that achieves the same or slightly better immune response with less mRNA in each dose (10 mcg in mNexspike compared to 50 mcg in adult doses of Spikevax). The two products may be used interchangeably when age appropriate.

In adults 65 years and older (and moderately or severely immunocompromised adults) who are recommended to receive a second dose 6 months after their first 2025–2026 formula dose, the minimum interval between the two recommended 2025–2026 season doses is 3 months for mNexspike, but only 2 months for the other COVID-19 vaccine products. If mNexspike is inadvertently administered after only 2 months, the dose counts as valid and does not need to be repeated.