Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the following Registration Statements:

(1) Registration Statement (Form S-8 No. 333-226498) pertaining to the Novavax, Inc. stock incentive plan and 2013 employee stock purchase plan,

(2) Registration Statement (Form S-3 No. 333-222365) pertaining to Novavax, Inc. common stock,

(3) Registration Statement (Form S-3 No. 333-215389) pertaining to Novavax, Inc. common stock,

(4) Registration Statement (Form S-8 No. 333-219829) pertaining to the Novavax, Inc. stock incentive plan,

(5) Registration Statement (Form S-8 No. 333-213069) pertaining to the Novavax, Inc. stock incentive plan and 2013 employee stock purchase plan,

(6) Registration Statement (Form S-8 No. 333-206354) pertaining to the Novavax, Inc. stock incentive plan,

(7) Registration Statement (Form S-8 No. 333-198121) pertaining to the Novavax, Inc. stock incentive plan,

(8) Registration Statement (Form S-8 No. 333-190600) pertaining to the Novavax, Inc. stock incentive plan,

(9) Registration Statement (Form S-8 No. 333-190599) pertaining to the Novavax, Inc. 2013 employee stock purchase plan,

(10) Registration Statement (Form S-8 No. 333-183113) pertaining to the Novavax, Inc. stock incentive plan,

(11) Registration Statement (Form S-8 No. 333-145298) pertaining to the Novavax, Inc. stock incentive plan,

(12) Registration Statement (Form S-8 No. 333-130990) pertaining to the Novavax, Inc. stock incentive plan,

(13) Registration Statement (Form S-8 No. 333-110401) pertaining to the Novavax, Inc. stock incentive plan,

(14) Registration Statement (Form S-8 No. 333-97931) pertaining to the Novavax, Inc. stock incentive plan,

(15) Registration Statement (Form S-8 No. 333-46000) pertaining to the Novavax, Inc. stock incentive plan,

(16) Registration Statement (Form S-8 No. 333-77611) pertaining to the Novavax, Inc. stock incentive plan,

(17) Registration Statement (Form S-8 No. 333-03384) pertaining to the Novavax, Inc. stock incentive plan

(18) Registration Statement (Form S-8 No. 33-80279) pertaining to the Novavax, Inc. stock incentive plan, and

(19) Registration Statement (Form S-8 No. 33-80277) pertaining to the Novavax, Inc. stock incentive plan

of our reports dated March 18, 2019, with respect to the consolidated financial statements of Novavax, Inc., and the effectiveness of internal control over financial reporting of Novavax, Inc., included in this Annual Report (Form 10-K) of Novavax, Inc. for the year ended December 31, 2018.

/s/ Ernst & Young LLP

Baltimore, Maryland

March 18, 2019