FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                      
1. Name and Address of Reporting Person * Brunn Carsten 2. Issuer Name and Ticker or Trading Symbol SELECTA BIOSCIENCES INC [ SELB ] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable)__X__ Director                    _____ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
President and CEO
(Last)         (First)         (Middle)
C/O SELECTA BIOSCIENCES, INC., 65 GROVE STREET
3. Date of Earliest Transaction (MM/DD/YYYY)
3/1/2021
(Street)
WATERTOWN, MA 02472
(City)       (State)       (Zip)
4. If Amendment, Date Original Filed (MM/DD/YYYY)
 
6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security
(Instr. 3)
2. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. Code
(Instr. 8)
4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)
6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock  3/1/2021    M    10937  A $0  222287  D   
Common Stock  3/2/2021    S(1)    5461  D $4.2588 (2) 216826  D   

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security 3. Trans. Date 3A. Deemed Execution Date, if any 4. Trans. Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
6. Date Exercisable and Expiration Date 7. Title and Amount of Securities Underlying Derivative Security
(Instr. 3 and 4)
8. Price of Derivative Security
(Instr. 5)
9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Restricted Stock Units   (3) 3/1/2021    M        10937    (4)  (4) Common Stock  10937.0  $0  76563  D   

Explanation of Responses:
(1)  Shares sold to satisfy withholding tax obligations upon the vesting of restricted stock units and to cover related broker fees.
(2)  The price reported is a weighted average price. The shares were sold in multiple transactions at per share prices ranging from $4.24 to $4.285. The Reporting Person undertakes to provide upon request to the SEC staff, the Issuer, or any stockholder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.
(3)  Each restricted stock unit represents a contingent right to receive one share of common stock.
(4)  This restricted stock unit vested as to 25% on December 1, 2019 and has vested, and will continue to vest, as to an additional 8.33% each quarter thereafter until fully vested. The restricted stock units have no expiration date.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director 10% Owner Officer Other
Brunn Carsten
C/O SELECTA BIOSCIENCES, INC.
65 GROVE STREET
WATERTOWN, MA 02472
X
President and CEO

Signatures
/s/ Matthew Bartholomae, Attorney-in-Fact for Carsten Brunn 3/3/2021
**Signature of Reporting Person Date