Exhibit
31.1





Certification Under Section 302





I, J. David Hansen, certify that:





1. I have reviewed this quarterly report on Form 10-Q/A
of MabVax Therapeutics Holdings,
Inc.;





2. Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact
necessary to make the statements made, in light of the
circumstances under which such statements were made, not misleading
with respect to the period covered by this report;





3. Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present in
all material respects the financial condition, results of
operations and cash flows of the registrant as of, and for, the
periods presented in this report;





4. The registrant’s other certifying officer(s) and I are
responsible for establishing and maintaining disclosure controls
and procedures (as defined in Exchange Act Rules 13a-15(e) and
15d-15(e)) and internal control over financial reporting (as
defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
registrant and have:





a)
Designed such disclosure controls and procedures, or caused such
disclosure controls and procedures to be designed under our
supervision, to ensure that material information relating to the
registrant, including its consolidated subsidiaries, is made known
to us by others within those entities, particularly during the
period in which this report is being prepared;





b)
Designed such internal control over financial reporting, or caused
such internal control over financial reporting to be designed under
our supervision, to provide reasonable assurance regarding the
reliability of financial reporting and the preparation of financial
statements for external purposes in accordance with generally
accepted accounting principles;





c)
Evaluated the effectiveness of the registrant’s disclosure
controls and procedures and presented in this report our
conclusions about the effectiveness of the disclosure controls and
procedures, as of the end of the period covered by this report
based on such evaluation; and





d)
Disclosed in this report any change in the registrant’s
internal control over financial reporting that occurred during the
registrant’s most recent fiscal quarter (the
registrant’s fourth fiscal quarter in the case of an Annual
Report) that has materially affected, or is reasonably likely to
materially affect, the registrant’s internal control over
financial reporting; and





5. The registrant’s other certifying officer(s) and I have
disclosed, based on our most recent evaluation of internal control
over financial reporting, to the registrant’s auditors and
the audit committee of the registrant’s Board of Directors
(or persons performing the equivalent functions):





a)
All significant deficiencies and material weaknesses in the design
or operation of internal control over financial reporting which are
reasonably likely to adversely affect the registrant’s
ability to record, process, summarize and report financial
information; and





b)
Any fraud, whether or not material, that involves management or
other employees who have a significant role in the
registrant’s internal control over financial
reporting.





Date:
April 24, 2019

By:
/s/ J. David
HansenJ.
David HansenChief
Executive Officer (Principal
Executive
Officer)