THIS WARRANT AND THE COMMON SHARES ISSUABLE UPON EXERCISE HEREOF HAVE NOT BEEN
      REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR UNDER THE
   SECURITIES LAWS OF ANY STATE OF THE UNITED STATES OR PROVINCE OF CANADA AND
        SUCH SECURITIES MAY NOT BE SOLD, PLEDGED OR OTHERWISE TRANSFERRED
    IN THE ABSENCE OF SUCH REGISTRATION OR AN APPLICABLE EXEMPTION THEREFROM


                          NORTH AMERICAN VACCINE, INC.

                    Warrant for the Purchase of Common Shares
                    -----------------------------------------

No.  W-3                                                          250,000 Shares
     ---

     FOR VALUE  RECEIVED,  NORTH  AMERICAN  VACCINE,  INC.  (the  "Company"),  a
Canadian corporation, hereby certifies that BioChem Pharma Inc. or its permitted
assigns (the "Holder") is entitled to purchase from the Company,  at any time or
from time to time after the date set forth on the signature  page,  but prior to
5:00 p.m. on October 28, 2001, two hundred fifty thousand  (250,000)  fully paid
and non-assessable  common shares, no par value, of the Company for an aggregate
purchase  price of One Million Two Hundred  Eighty-Four  Thousand  Three Hundred
Seventy-Five U.S. Dollars (US$1,284,375) (computed on the basis of US$5.1375 per
share).  (Hereinafter,  (i) said common  shares,  together with any other equity
securities  which may be issued by the  Company in  substitution  therefor,  are
referred  to as  the  "Common  Shares":,  (ii)  the  Common  Shares  purchasable
hereunder are referred to as the "Warrant Shares",  (iii) the aggregate purchase
price payable  hereunder for the Warrant Shares is referred to as the "Aggregate
Warrant Price", (iv) the price payable hereunder for each of the Warrant Shares,
as  adjusted  in the manner set forth in Section 3, is  referred  to as the "Per
Share Warrant Price" and (v) this Warrant and all warrants  hereafter  issued in
exchange or substitution for this Warrant are referred to as the "Warrants") The
Aggregate  Warrant  Price is not subject to  adjustment.  The Per Share  Warrant
Price and the number of Warrant  Shares are subject to adjustment as hereinafter
provided.

     1. EXERCISE OF WARRANT. This Warrant may be exercised, in whole at any time
or in part from time to time  (such  partial  exercises  to be in amounts of not
less  than  1,000  Warrant  Shares),  on and  after  the date  set  forth on the
signature  page,  but prior to 5:00 p.m. on October 28,  2001,  by the Holder of
this Warrant by the surrender of this Warrant (with the subscription form at the
end hereof duly executed) at the principal office of the Company in Columbia, MD
together with proper payment of the Aggregate  Warrant Price  applicable on such
date,  or the  proportionate  part thereof if this Warrant is exercised in part.
Payment for Warrant  Shares  shall be made by (i) check  payable to the order of
the Company,  (ii) wire transfer to an account  designated by and in the name of
the Company, (iii) by delivery to the Company of debt securities for which it is
the issuer and bound to make payment in the stated principal  amount,  where the
principal  amount on such debt security  delivered to the Company for retirement
is equal to the  Aggregate  Warrant  Price;  or (iv) by any  combination  of the
methods set forth in (i) through (iii),  above.  If this Warrant is exercised in
part, this Warrant must be exercised for a number of whole Warrant  Shares,  and
the Holder is entitled to receive a new Warrant  covering  the number of Warrant


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<PAGE>


Shares in respect of which this Warrant has not been exercised and setting forth
the proportionate part of the Aggregate Warrant Price applicable to such Warrant
Shares.  Upon  such  surrender  of  this  Warrant,  the  Company  will  issue  a
certificate or  certificates in the name of the Holder for the largest number of
whole Warrant  Shares to which the Holder shall be entitled and, if this Warrant
is  exercised in whole,  in lieu of any  fractional  Warrant  Share to which the
Holder shall be entitled,  cash equal to the fair value of such fractional share
(determined in such  reasonable  manner as the Board of Directors of the Company
shall determine).

     2.  RESERVATION OF WARRANT  SHARES.  The Company agrees that,  prior to the
expiration of this Warrant,  the Company will at all times have  authorized  and
reserve,  and will keep  available,  solely for  issuance or  delivery  upon the
exercise of this Warrant,  the Warrant Shares free and clear of all restrictions
on sale or transfer (except as may arise under  applicable  securities laws) and
free and clear of all preemptive rights.

     3. PROTECTION  AGAINST  DILUTION.  (a) If, at any time or from time to time
after the date of this  Warrant,  the Company  shall (i) issue to the holders of
the Common Shares any Common Shares by way of a stock  dividend;  (ii) subdivide
its outstanding Common Shares into a greater number of shares; (iii) combine its
outstanding number of Common Shares into a smaller number (i.e., a reverse stock
split);  or (iv) issue by  reclassification  of its Common  Shares any shares of
capital stock of the Company then,  and in each such case, the Per Share Warrant
Price in effect  immediately prior to the date of such action shall be adjusted,
or further adjusted, to a price (to the nearest cent) determined by dividing (x)
an amount equal to the number of Common Shares outstanding  immediately prior to
such issuance  multiplied  by the Per Share Warrant Price in effect  immediately
prior to such  issuance  by (y) the total  number of Common  Shares  outstanding
immediately  after such issuance.  Upon each adjustment in the Per Share Warrant
Price  resulting  from a stock  split or stock  dividend,  the number of Warrant
Shares  shall be adjusted by dividing  the  Aggregate  Warrant  Price by the Per
Share Warrant Price in effect immediately after such adjustment.  Notice of each
such  adjustment  and each such  readjustment  shall be forthwith  mailed to the
Holder.

     (b) If the  Company  shall be  consolidated  with or  merged  into  another
corporation,  or shall sell all or substantially  all of its assets as part of a
reorganization  to which  the  Company  is a party  within  the  meaning  of the
Internal Revenue Code of 1986, as presently in effect, or shall issue a security
convertible  into its Common  Shares as a dividend  on its Common  Shares,  each
Warrant  Share shall be replaced for the purposes  hereof by the  securities  or
properties  issuable  or  distributed  in respect of one Common  Share upon such
consolidation,  merger, sale,  reclassification or reorganization,  and adequate
provisions  to that  effect  shall be made at the time  thereof.  Notice of such
consolidation,  merger,  sale,  reclassification or reorganization,  and of said
provisions  so proposed to be made,  shall be mailed to the Holder not less than
15 days prior to such event.

     (c) If the Board of Directors of the Company  shall declare any dividend or
other distribution in cash with respect to the Common Shares,  other than out of
surplus,  the Company  shall mail notice  thereof to the Holder not less than 15


                                     - 2 -
<PAGE>


days prior to the record  date fixed for  determining  shareholders  entitled to
participate in such dividend or other distribution.

     (d) If , during the term of this  Warrant,  the Company shall issue or sell
its Common Shares for a consideration  per share less than the Per Share Warrant
Price  immediately  prior to the time of such issue or sale, then forthwith upon
such issue or sale, the Per Share Warrant Price in effect  immediately  prior to
such issue or sale shall be  reduced to the lower of the prices  (calculated  to
the nearest cent) determined as follows:

          (1) by  dividing  (A) an amount  equal to the sum of (i) the number of
shares of  Common  Stock  outstanding  immediately  prior to such  issue or sale
multiplied  by  the   then-existing  Per  Share  Warrant  Price,  and  (ii)  the
consideration,  if any,  received by the Company upon such issue or sale, by (B)
the total number of Common Shares  outstanding  immediately  after such issue or
sale; and

          (2) by multiplying  the Per Share Warrant Price in effect  immediately
prior to the time of such issue or sale by a fraction,  the  numerator  of which
shall be (A) the sum of (i) the number of Common Shares outstanding  immediately
prior to such issue or sale multiplied by the market price  immediately prior to
such issue or sale; and (ii) the consideration received by the Company upon such
sale, divided by (B) the total number of Common Shares  outstanding  immediately
after such issue or sale, and the denominator of which shall be the market price
immediately prior to such issue or sale.

     4. FULLY PAID  SHARES;  TAXES.  The Company  agrees that the Common  Shares
represented by each and every  certificate  for Warrant Shares  delivered on the
exercise of this Warrant shall, at the time of such delivery,  be validly issued
and outstanding,  fully paid and  non-assessable.  The Company further covenants
and agrees that it will pay, when due and payable, any and all Federal and state
stamp,  original  issue or similar  taxes which may be payable in respect of the
issue of any Warrant Share or certificate therefor.

     5. TRANSFERABILITY.  This Warrant and the Warrant Shares shall not be sold,
transferred,  assigned or  hypothecated  by the Holder except (i) pursuant to an
effective  registration  statement under the Securities Act of 1933, as amended,
and  qualification  for sale  under all other  applicable  state and  provincial
securities rules and regulations  [collectively the "Securities  Acts"]; or (ii)
in full  compliance  with all  requirements  necessary to establish an exemption
from the registration  requirements of the Securities Acts. In order to properly
establish  compliance with (ii), above, the Company shall be entitled to request
and  receive  in  advance  of  authorizing  any sale,  transfer,  assignment  or
hypothecation  of this  Warrant or any of the Warrant  Shares:  (x)  appropriate
transferor and transferee  representation letters supporting a claimed exemption
from registration requirements of the Securities Acts; (y) an opinion of counsel
for the holder of the Warrant and/or Warrant Shares  reasonably  satisfactory to
the Company that the  proposed  transfer  from the holder of the Warrant  and/or
Warrant Shares to the transferee is exempt from the registration requirements of
the  Securities  Act;  and (z) such  other  documentation,  representations  and


                                     - 3 -
<PAGE>


filings as may be reasonably required by counsel in order to issue the foregoing
opinion.  The  Company  may treat the  registered  holder of this  Warrant as it
appears on the Company's books at any time as the Holder for all purposes.

     6. LOSS,  ETC. OF WARRANT.  Upon  receipt of evidence  satisfactory  to the
Company of the loss,  theft,  destruction or mutilation of this Warrant,  and of
indemnity reasonably  satisfactory to the Company, if lost, stolen or destroyed,
and upon  surrender and  cancellation  of this Warrant,  if mutilated,  and upon
reimbursement of the Company's reasonable incidental expenses, the Company shall
execute  and  deliver  to the  Holder a new  Warrant  of like  date,  tenor  and
denomination.

     7. WARRANT HOLDER NOT  SHAREHOLDER.  Except as otherwise  provided  herein,
this  Warrant does not confer upon the Holder any right to vote or to consent or
to receive  notice as a shareholder  of the Company,  as such, in respect of any
matters whatsoever,  or any other rights or liabilities as a shareholder,  prior
to the exercise hereof.

     8. COMMUNICATION. No notice or other communication under this Warrant shall
be effective unless,  but any notice or other  communication  shall be effective
and shall be deemed to have been given if, the same is in writing  and is mailed
by first-class mail, postage prepaid, addressed to:

     (a) the Company at North American  Vaccine,  Inc., 10150 Old Columbia Road,
Columbia, MD 21046 Attention:  Vice President-Finance,  or such other address as
the Company has designated in writing to the Holder, or

     (b) the Holder at BioChem  Pharma  Inc.,  275  Armand  Frappier  Boulevard,
Laval, H7V 4A7 Quebec, Canada Attention:  Executive Vice President-Investments &
Subsidiaries,  or such other address as the Holder has  designated in writing to
the Company.

     9. HEADINGS. The headings of this Warrant have been inserted as a matter of
convenience and shall not affect the construction hereof.

     10.  APPLICABLE  LAW.  This Warrant  shall be governed by and  construed in
accordance with the laws of the State of New York.


                                     - 4 -
<PAGE>


     IN WITNESS WHEREOF, NORTH AMERICAN VACCINE, INC. has caused this Warrant to
be signed by its Vice  President-Finance  and its corporate  seal to be hereunto
affixed and attested by its Assistant Secretary this 28th day of October, 1999.

ATTEST:                                     NORTH AMERICAN VACCINE, INC.



/s/ Russell P. Wilson                       By: /s/ Lawrence J. Hineline
---------------------                           ------------------------
Russell P. Wilson                               Lawrence J. Hineline
  Assistant Secretary                           Vice President-Finance


[Corporate Seal]

                                      - 5 -