By Bhanvi Satija Dec 24 (Reuters) - Sanofi (SNY) will buy U.S. vaccines company Dynavax Technologies (DVAX) for around $2.2 billion (1.9 billion euros), the French drugmaker said on Wednesday, a deal that will give it access to an approved hepatitis ​B vaccine. Sanofi has made a string of acquisitions this year, as it looks to diversify growth beyond ‌its blockbuster asthma drug Dupixent. It bought UK private biotech firm Vicebio for $1.5 billion in July shortly after finalising an up to $9.5 billion dea ...