CREDIT AGREEMENT dated as of

ICON LUXEMBOURG, S. R.L.,

INDIGO MERGER SUB, INC.,

ICON CLINICAL RESEARCH LIMITED,

ICON GLOBAL TREASURY UNLIMITED COMPANY,

ICON US HOLDINGS INC.

and ICON CLINICAL INVESTMENTS, LLC,

ICON PUBLIC LIMITED COMPANY,

as Holdings and a Guarantor,

THE SUBSIDIARY GUARANTORS PARTY HERETO,

as Subsidiary Guarantors

The Lenders Party Hereto,

as Administrative Agent

CITIBANK, N.A., LONDON BRANCH,

CITIGROUP GLOBAL MARKETS INC. and

J.P. MORGAN SECURITIES PLC,

as Joint Bookrunners,

CITIGROUP GLOBAL MARKETS INC.,

BANCO SANTANDER S.A.,

HSBC CONTINENTAL EUROPE SA,

J.P. MORGAN SECURITIES PLC and

MORGAN STANLEY BANK INTERNATIONAL LIMITED,

as Joint Lead Arrangers

CREDIT AGREEMENT, dated as

of July 1, 2021 (as amended, restated, amended and restated, supplemented or otherwise modified from time to time, this "Agreement"),

among ICON LUXEMBOURG, S. R.L., a soci t responsabilit limit e incorporated

and existing under Luxembourg law, having its registered office at 61, rue de Rollingergrund, L-2440, Luxembourg and registered

with the Luxembourg register of commerce and companies (R.C.S. Luxembourg) under number B66588 (the "Lux Borrower"),

ICON Clinical Investments, LLC, a Delaware limited liability company (the "Lux U.S. Subsidiary Borrower"), INDIGO

MERGER SUB, INC., a Delaware corporation ("Merger Sub" and, prior to the consummation of the Acquisition, the

"U.S. Borrower") (which, after giving effect to the Acquisition on the Closing Date, shall be succeeded by PRA

Health Sciences, Inc., a Delaware corporation (the "Target" and, following the consummation of the Acquisition,

the "U.S. Borrower"), ICON PUBLIC LIMITED COMPANY, an Irish public limited company ("Holdings"),

the Revolving Borrowers (as such term is defined in Article I), each Additional Borrower, the Subsidiary Guarantors (as

such term is defined in Article I) party hereto, the LENDERS from time to time party hereto, CITIBANK, N.A., as Administrative

Agent, and CITIBANK, N.A., LONDON BRANCH, as Collateral Agent.

NOW, THEREFORE, the parties

hereto agree as follows:

Section 1.01 Defined

Terms. As used in this Agreement, the following terms have the meanings specified below:

when used in reference to any Loan or Borrowing, refers to a Loan, or the Loans comprising such Borrowing, bearing interest at

a rate determined by reference to the Alternate Base Rate.

Lender" has the meaning assigned to such term in Section 2.11(e).

means Indebtedness incurred in the ordinary course of business arising in connection with any automated clearinghouse transfers

of funds or other payment processing service.

means the merger of Merger Sub with and into the Target, with the Target as the surviving corporation, as provided for in the Acquisition

Agreement and the related transactions.

"Acquisition Agreement"

means the Agreement and Plan of Merger dated as of February 24, 2021 among Holdings, U.S. Holdco, Merger Sub and the Target (including,

without limitation, all exhibits, schedules and disclosure letters thereto), as the same may be altered, amended, changed, supplemented

or with any provision or condition therein waived.

"Acquisition Agreement

Representations" means such representations and warranties made by or with respect to the Target and its subsidiaries

in the Acquisition Agreement as are material to the interests of the Lenders, but only to the extent that Holdings (or its applicable

subsidiaries) have the right (taking into account any applicable cure periods) to terminate its obligation to consummate the Acquisition

under the Acquisition Agreement or the right not to consummate the Acquisition pursuant to the Acquisition Agreement as a result

of a breach of such representations and warranties, in each case in accordance with the terms thereof.

"Acquisition Documents"

means the Acquisition Agreement and any other documents executed or issued, or to be executed or issued, by or on behalf of the

Target and/or the U.S. Borrower in respect of the Acquisition (but excluding the Loan Documents).

"Additional Borrower"

means any one or more Restricted Subsidiaries that is or becomes a Subsidiary Guarantor designated by Holdings as a borrower of

any Incremental Loans hereunder, Revolving Loans or Other Refinancing Loans; provided, however, that only Restricted

Subsidiaries organized under the laws of Ireland, Luxembourg, England and Wales and/or a jurisdiction located in the United States

may be designated by Holdings as Additional Borrowers; provided, further, that the Additional Borrower shall have

satisfied the requirements set forth in Section 4.01(c), and for such purposes, any reference to the Closing Date in such Section

4.01(c) shall be deemed to be a reference to the date on which such Subsidiary Guarantor becomes an Additional Borrower. For the

avoidance of doubt, any Restricted Subsidiary designated as an Additional Borrower shall cease to be an "Additional Borrower"

upon the repayment of all Loans (or, in the case of an Additional Borrower that is a Revolving Borrower, the repayment of all Loans

and termination of all Revolving Commitments) in respect of which such Restricted Subsidiary was designated as an "Additional

Borrower" and shall be deemed to be a Guarantor.

has the meaning assigned to such term in Section 2.20(a).

Rate" means, with respect to any Eurocurrency Borrowing denominated in euros, for any Interest Period, an interest rate

per annum (rounded upwards, if necessary, to the next 1/16 of 1%) equal to the sum of (a) the EURIBOR Rate for such Interest Period

multiplied by (b) the Statutory Reserve Rate; provided that, with respect to Revolving

Loans, such rate shall not be less than zero.

Rate" means, with respect to any Eurocurrency Borrowing denominated in any Agreed Currency other than euros, for any

Interest Period, an interest rate per annum (rounded upwards, if necessary, to the next 1/16 of 1%) equal to the sum of (a) the

LIBO Rate for such Interest Period multiplied by (b) the Statutory Reserve Rate; provided

that (i) with respect to Revolving Loans, such rate shall not be less than zero and (ii) with respect to the Initial Term Loans,

such rate shall not be less than 0.50%.

Agent" means Citibank, N.A., in its capacity as administrative agent for the Lenders hereunder.

Questionnaire" means an Administrative Questionnaire in a form supplied by the Administrative Agent.

Institution" means (a) any EEA Financial Institution or (b) any UK Financial Institution.

means, with respect to a specified Person, another Person that directly, or indirectly through one or more intermediaries, Controls

or is Controlled by or is under common Control with the Person specified.

has the meaning assigned to such term in Section 9.01(c).

has the meaning assigned to such term in Section 8.01.

means (i) Dollars, (ii) euro (solely with respect to Revolving Loans and Letters of Credit), (iii) Pounds Sterling (solely

with respect to Revolving Loans and Letters of Credit) and (iv) any other Foreign Currency agreed to by the Administrative Agent,

each of the Lenders and each Issuing Bank of the applicable Class of Loans.

and Security Principles" means the Agreed Guarantee and Security Principles set forth on Schedule 1.01A.

For the avoidance of doubt, the Agreed Guarantee and Security Principles shall only apply to Guarantees proposed to be granted

by, assets of, and Equity Interests in, Holdings and the Foreign Subsidiaries.

has the meaning assigned to such term in the preamble hereto.