Irrevocable Undertaking This irrevocable undertaking agreement (the "Agreement") has been made on [ ] June 2013, by and between: 1. Novavax, Inc., ("Novavax"); and 2. [ ] (the "Obligated Party"). Novavax and the Obligate

Irrevocable Undertaking

This irrevocable undertaking agreement (the "Agreement")

has been made on [ ] June 2013, by and between:

Novavax and the Obligated Party are each referred to as a "Party"

and jointly as the "Parties".

also intends to make a private offer whereby holders of vested and unvested stock options3 who agree to waive their

rights under the stock options will receive 0.62324 shares of its common stock for each stock option in Isconova.

SEK 16.50 per share payable in shares of Novavax common stock. Novavax common stock

will be valued at the volume-weighted average share price over the

15 trading days prior to announcement.

Cashed out at fair market value determined using the Black-Scholes Model.

Employee and board member stock options 2012/2016.

SEK 8.30 per stock option payable in shares of Novavax common stock, representing the

offer price per share (SEK 16.50) reduced by the strike price per share for the stock options (SEK 8.20).

The warranties and undertakings set forth in Section 3.2(a) shall not apply to (i) transactions relating to shares of common stock

of Novavax or other securities acquired in open market transactions after the closing of the Offer or (ii) transfers of shares

of common stock of Novavax as a bona fide gift or by will or pursuant to the laws of descent and distribution; provided

that in the case of any transfer or distribution pursuant to clause (ii) each donee

or distributee shall sign and deliver a lock-up letter substantially in the form of Section 3.2.]

____________________

This Agreement has been entered into in two copies, of which

each Party has taken one.