Zoe Healey and Wendy Gerber have joined the agency's London operation as senior associates.
Healey has come from rival agency Chandler Chicco Companies, where she was senior consultant.
At CCC, Healey worked on strategy of global and local integrated programmes and campaigns for clients including priobiotic brand Actimel.
Gerber joins WCG from MS&L, where she led the global account team for blood-thinning drug Efient, in addition to working with clients at Sanofi-aventis and Solvay.
She has also recently worked with the World Heart Federation on a global campaign to support patients recovering from a heart event.
The hires follow the appointment in January of Gail Cohen as global managing director, based in the US. Cohen joined the agency in the newly created role last month.
Cohen was formerly chair of Burson-Marsteller's healthcare practice, and prior to that headed the healthcare arm of Chandler Chicco Agency.
The latest appointments take the agency's London headcount to eight. They will report to London MD Nigel Breakwell, former Edelman UK healthcare director and joint CEO.
The London arm of WeissComm was set up in 2008 by Breakwell. It has ten clients, with a focus on oncology, rheumatoid arthritis and cardiovascular disease.
As well its core PR work, WCG has extended its remit to include advocacy relations, access and clinical trial recruitment.