Biotech giant Moderna announced it will lay off 10% of its workforce in a move CEO Stéphane Bancel called “a difficult decision but necessary step forward,” in an internal memo sent to employees today.

The layoffs are part of an ongoing effort to reduce operating costs amid government and competitive challenges to its vaccine business.

Moderna said on Thursday it would trim roughly 10% of its global workforce and have fewer than 5,000 employees by the end of the year, as the biotech accelerates its cost-cutting efforts amid declining sales of COVID-19 vaccines.