Exhibit 23.3
CONSENT OF INDEPENDENT AUDITORS
We consent to the incorporation by reference in this Registration Statement on Form S-4 of our
report dated February 26, 2009, relating to the combined financial statements of the
Merck/Schering-Plough Cholesterol Partnership appearing in the Annual Reports on Form 10-K of Merck
& Co., Inc. and Schering-Plough Corporation for the year ended December 31, 2008, and to the
reference to us under the heading Experts in the Joint Proxy Statement/Prospectus, which is part
of this Registration Statement.
/s/ DELOITTE & TOUCHE LLP
Parsippany, New Jersey
May 20, 2009
May 20, 2009