Merck is moving ahead with ambitious hiring plans at a massive vaccine factory in Durham, with a goal of adding another 150 employees this year.

The new jobs will come on top of the 230 people Merck hired last year, increasing the current total to 450. The facility is preparing to package and eventually grow vaccines to protect against chicken pox and other diseases.

The company announced plans in 2004 for the campus on 262 acres in northern Durham's Treyburn Corporate Park, further reinforcing the Triangle as a hub for vaccine production. In December, Novartis announced plans to expand its massive Holly Springs vaccine plant, and add 100 more jobs during the next two years.

At Merck this year, one focus is to catch up with expansions and rapid hiring, plant manager John Wagner said in a phone interview.