Filed by ICON plc

This communication is filed pursuant to Rule 425 under the United States Securities Act of 1933

Subject Company: PRA Health Sciences, Inc.

(Commission File No. 001-36732)

Date: May 11, 2021

The following communication was made available by ICON plc to certain of its employees on May 10, 2021.”

Leadership Change FAQs

(For Top 100 Leaders Reference Only – Do not Forward)

1. When does the new leadership team come into effect?

The new leadership team will be effective from the date of the closing of the acquisition. We currently do not have a confirmed date for closing, however we anticipate that it will take place in early Q3.

2. There has been some changes in terms of where certain services sit within the organisation, why is this?

All service areas and business support functions are important to the company’s current and future growth. However, the combined company is double the size of the individual ICON and PRA organisations and will be:

i. World leader in Functional Service Provision (FSP)

ii. Global number 2 in full service Ph 2/3 clinical research

iii. Global number 2 in Early Phase clinical research

iv. Global number 3 in Late Phase & RWE

v. Global number 4 in Central & Speciality Laboratory Services

The organisation and leadership team is structured to enable us to have a focused approach to delivering differentiated, global solutions that will reduce development time and cost for all customers and support a much larger organisation. The new leadership team supports our strategic direction to become the world leading healthcare intelligence and clinical CRO. More details on how the new appointments support key strategic objectives will be discussed in an upcoming Q&A with the CEO

3. What will be the process for announcing the next level of leadership?

Each of the appointed leaders will review their new organisations over the coming weeks with a view to developing the future leadership teams that will report to them. We will continue to keep you informed as we make further organisational decisions and we expect to make further leadership announcements in the coming weeks. It will be important however to maintain delivery and business continuity as we approach Day 1 so in most cases current organisation structures will stay in place for now.

4. What can I expect on the day the new leadership team comes into effect? When will I start to see real movement in terms of integrating operational groups?

Both companies will continue to operate as separate companies, independent of each other until the acquisition closes, which we currently anticipate will be early Q3. After the acquisition closes, the new leadership structure will come into effect. Between now and then, however, work stream integration planning will have commenced and each of the appointed leaders will also have reviewed their new organisations and will have announced their respective leadership teams.

After close, more detailed discussions around structures, combined service offerings and go-to- market strategies will take place as we look to harness the outstanding leadership and talent that resides in both organisations to deliver operational excellence and continue our focus and mission on patient-centered drug and device development. Considered and effective integration will take some time and will involve regular communication and dialogue with employees as we work through the process. Ongoing focus on delivering for customers will be paramount during the period between today and acquisition close as well as during the integration period.

Cautionary Note Regarding Forward-Looking Statements

This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements generally include statements regarding the potential transaction between ICON public limited company, a public limited company in Ireland (“ICON”) and PRA Health Sciences, Inc., a Delaware corporation (“PRA”), including any statements regarding the expected timetable for completing the potential transaction, the ability to complete the potential transaction, the expected benefits of the potential transaction (including anticipated synergies, projected financial information and future opportunities) and any other statements regarding ICON’s and PRA’s future expectations, beliefs, plans, objectives, results of operations, financial condition and cash flows, or future events or performance. These statements are often, but not always, made through the use of words or phrases such as “anticipate,” “intend,” “plan,” “believe,” “project,” “estimate,” “expect,” “may,” “should,” “will” and similar expressions. All such forward-looking statements are based on current expectations of ICON’s and PRA’s management and therefore involve estimates and assumptions that are subject to risks, uncertainties and other factors that could cause actual results to differ materially from the results expressed in the statements. Key factors that could cause actual results to differ materially from those projected in the forward-looking statements include the ability to obtain the requisite ICON and PRA stockholder approvals; uncertainties as to the timing to consummate the potential transaction; the risk that a condition to closing the potential transaction may not be satisfied; the risk that regulatory approvals are not obtained or are obtained subject to conditions that are not anticipated by the parties; litigation relating to the potential transaction that has been or could be instituted against ICON, PRA or their respective directors; the effects of disruption to ICON’s or PRA’s respective businesses; restrictions during the pendency of the potential transaction that may impact ICON’s or PRA’s ability to pursue certain business opportunities or strategic transactions; the effect of this communication on ICON’s or PRA’s stock prices; transaction costs; ICON’s ability to achieve the benefits from the proposed transaction; ICON’s ability to effectively integrate acquired operations into its own operations; the ability of ICON or PRA to retain and hire key personnel; unknown liabilities; and the diversion of management time on transaction-related issues. Other important factors that could cause actual results to differ materially from those in the forward-looking statements include the effects of industry, market, economic, political or regulatory conditions outside of ICON’s or PRA’s control (including public health crises, such as pandemics and epidemics); risks regarding PRA’s ability to maintain large customer contracts or enter into new contracts; PRA’s ability to attract suitable investigators and patients for its clinical trials; PRA’s ability to keep pace with rapid technological change; PRA’s potential liability if a patient is harmed; and the factors set forth under the heading “Risk Factors” of ICON’s Annual Report on Form 20-F and PRA’s Annual Report on Form 10-K and most recent Quarterly Report on Form 10-Q, and in subsequent filings with the U.S. Securities and Exchange Commission (the “SEC”). These risks, as well as other risks associated with the potential transaction, are more fully discussed in the joint proxy statement/prospectus filed with the SEC in connection with the proposed transaction. Other unpredictable or unknown factors not discussed in this communication could also have material adverse effects on forward-looking statements. Neither ICON nor PRA assumes any obligation to update any forward-looking statements, except as required by law. Readers are cautioned not to place undue reliance on these forward-looking statements that speak only as of the date hereof.

No Offer or Solicitation

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offer of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

Important Information for Investors and Stockholders

In connection with the potential transaction, ICON has filed a registration statement on Form F-4 (File No. 333-254891) with the SEC containing a prospectus of ICON that also constitutes a proxy statement of each of ICON and PRA. The registration statement, as amended, was declared effective, by the SEC on April 28, 2021.  Each of ICON and PRA commenced mailing copies of the definitive joint proxy statement/prospectus to stockholders of ICON and PRA, respectively, on or about April 28, 2021.  ICON and PRA may also file other documents with the SEC regarding the potential transaction. This communication is not a substitute for the joint proxy statement/prospectus or registration statement or for any other document that ICON or PRA have filed or may file with the SEC in connection with the potential transaction. INVESTORS AND SECURITY HOLDERS OF ICON AND PRA ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS AND OTHER DOCUMENTS THAT ARE FILED OR WILL BE FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THESE DOCUMENTS, CAREFULLY AND IN THEIR ENTIRETY BECAUSE THEY CONTAIN IMPORTANT INFORMATION. Investors and security holders are able to obtain free copies of the joint proxy statement/prospectus and other documents filed with the SEC by ICON or PRA through the website maintained by the SEC at http://www.sec.gov. Copies of the documents filed with the SEC by ICON are available free of charge on ICON’s website at https://www.iconplc.com and copies of the documents filed with the SEC by PRA are available free of charge on PRA’s website at https://www.prahs.com/. Additionally, copies may be obtained by contacting the investor relations departments of ICON or PRA.

ICON and PRA and certain of their respective directors, certain of their respective executive officers and other members of management and employees may be considered participants in the solicitation of proxies with respect to the potential transaction under the rules of the SEC. Information about the directors and executive officers of ICON is set forth in its annual report on Form 20-F, which was filed with the SEC on February 24, 2021. Information about the directors and executive officers of PRA is set forth in its Amendment to Annual Report on Form 10-K/A for the fiscal year ended December 31, 2020, which was filed with the SEC on March 30, 2021. These documents can be obtained free of charge from the sources indicated above. Additional information regarding the interests of such participants in the solicitation of proxies in respect of the potential transaction are included in the registration statement and joint proxy statement/prospectus and other relevant materials filed with the SEC.

The term “PRA” and such terms as “the company,” “the corporation,” “our,” “we,” “us” and “its” may refer to PRA Health Sciences, Inc., one or more of its consolidated subsidiaries, or to all of them taken as a whole. All of these terms are used for convenience only and are not intended as a precise description of any of the separate companies, each of which manages its own affairs.