Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation These condensed consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. As of December 31, 2020, the Company’s accounts included Vaccinex Products, LP, a Delaware limited partnership (“Vaccinex Products”), and VX3 (DE) LP, a Delaware limited partnership (“VX3”). VX3 was established in October 2017 by a group of Canadian investors and was determined to be a variable interest entity (“VIE”) in which the Company is the primary beneficiary. During the nine months ended September 30, 2021 all remaining limited partnership interests in VX3 were exchanged for shares of our common stock in accordance with the terms of the respective exchange agreement (See Note 10 and Note 15). Vaccinex Products and VX3 were subsequently dissolved as of September 3, 2021 and accordingly no longer are included in the condensed consolidated financial statements. The Company consolidates any VIE of which it is the primary beneficiary. The Company presents its noncontrolling interests as a separate component of stockholders’ equity (deficit). Prior to the exchange of partnership units for common shares (see Note 10) the Company presented the net loss of VX3 equal to the percentage ownership interest retained in such entity by the respective noncontrolling party, and as a separate component within its consolidated statements of operations and comprehensive loss. The financial position of Vaccinex Products and VX3 were not material as of December 31, 2020, and there were no gains or losses for Vaccinex Products or VX3 for the nine month period ended September 30, 2021 and the three and nine month periods ended September 30, 2020. All intercompany transactions and balances have been eliminated. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information (Accounting Standards Codification (“ASC”) 270, Interim Reporting) and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, these financial statements do not include all of the information necessary for a full presentation of financial position, results of operations, and cash flows in conformity with GAAP. In the opinion of management, the condensed consolidated financial statements reflect all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the results of the Company for the periods presented. Intercompany transactions and balances have been fully eliminated in consolidation. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 31, 2021.
Use of Estimates	Use of Estimates These condensed consolidated financial statements have been prepared in conformity with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements and the reported amount of expenses during the reporting period. Such management estimates include those relating to assumptions used in the valuation of stock option awards, and valuation allowances against deferred income tax assets. Actual results could differ from those estimates.
Concentration of Credit Risk, Other Risks and Uncertainties	Concentration of Credit Risk, Other Risks and Uncertainties Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash equivalents are deposited in interest-bearing money market accounts. Although the Company deposits its cash with multiple financial institutions, cash balances may occasionally be in excess of the amounts insured by the Federal Deposit Insurance Corporation. Management believes the financial risk associated with these balances is minimal and has not experienced any losses to date. The Company depends on third-party manufacturers for the manufacture of drug substance and drug product for clinical trials. The Company also relies on certain third parties for its supply chain. Disputes with these third- party manufacturers or shortages in goods or services from third-party suppliers could delay the manufacturing of the Company’s product candidates and adversely impact its results of operations.
Convertible Instruments	Convertible Instruments The Company applies the accounting standards for derivatives and hedging and for distinguishing liabilities from equity when accounting for hybrid contracts that contain conversion options and other embedded features. The accounting standards require companies to bifurcate embedded features from their host instruments and account for them as free-standing derivative financial instruments according to certain criteria. The criteria include circumstances in which (i) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (ii) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (iii) a separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument. The Company’s derivative instrument related to certain features embedded within the Company’s 8% Original Issue Discount Senior Secured Convertible Debenture (“the Debenture”) is discussed in Note 9. The derivative is accounted for as a derivative liability and remeasured to fair value as of each balance sheet date and the related remeasurement adjustments are included in interest expense in the Company’s condensed consolidated statement of operations and comprehensive loss, as discussed in Note 4.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Not Yet Adopted In June 2016, the Financial Accounting Standards Board (“the FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Measurement of Credit Losses on Financial Instruments” to improve reporting requirements specific to loans, receivables, and other financial instruments. The new standard requires that credit losses on financial assets measured at amortized cost be determined using an expected loss model, instead of the current incurred loss model, and requires that credit losses related to available-for-sale debt securities be recorded through an allowance for credit losses and limited to the amount by which carrying value exceeds fair value. The new standard also requires enhanced disclosure of credit risk associated with financial assets. The standard is effective for interim and annual periods beginning after December 15, 2022 with early adoption permitted. Based on the composition of the Company’s financial assets, current market conditions and historical credit loss activity, the adoption of this standard is not expected to have a material impact on the Company’s condensed consolidated financial statements. Accounting Pronouncements Recently Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02), which requires a lessee to recognize in its consolidated balance sheet a liability to make lease payments and also a right-of-use asset representing its right to use the underlying asset for the lease term. ASU 2016-02 is effective for the Company for annual periods beginning after December 15, 2020 and interim periods within fiscal years beginning after December 15, 2021, requiring the use of a modified retrospective transition approach. In July 2018, the FASB issued ASU No. 2018-11, Leases, Targeted Improvements to ASC 842, Leases, (“ASU 2018-11”), which contains certain amendments to ASU 2016-02 intended to provide relief in implementing the new standard. ASU 2018-11 provides registrants with an option to not restate comparative periods presented in the financial statements. The Company has elected this new transition approach using the effective date of the standard, for which comparative periods will be presented in accordance with the previous guidance in Accounting Standards Codification (“ASC”) 840, Leases. The Company has elected to utilize the available package of practical expedients permitted under the transition guidance within the new standard, which does not require the reassessment of the following: (i) whether existing or expired arrangements are or contain a lease, (ii) the lease classification of existing or expired leases, and (iii) whether previous initial direct costs would qualify for capitalization under the new lease standard. Additionally, the Company has made an accounting policy election to keep leases with an initial term of 12 months or less off of its balance sheet. As an emerging growth company, the Company is not required to reflect the effects of adoption in its consolidated financial statements until it files its annual report for the fiscal year ending December 31, 2021. The Company, however, has evaluated the impact of the new standard on its consolidated financial statements and related disclosures, concluding that the impact will result in the recognition of an operating lease right-of-use asset and corresponding lease obligation on the Company’s consolidated balance sheet as of January 1, 2021 in the amount of approximately $0.3 million, relating to the Company’s lease for its corporate headquarters in Rochester, New York.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2021

These condensed consolidated financial statements reflect the accounts and operations of the Company and those of its subsidiaries in which the Company has a controlling financial interest. As of December 31, 2020, the Company’s accounts included Vaccinex Products, LP, a Delaware limited partnership (“Vaccinex Products”), and VX3 (DE) LP, a Delaware limited partnership (“VX3”). VX3 was established in October 2017 by a group of Canadian investors and was determined to be a variable interest entity (“VIE”) in which the Company is the primary beneficiary. During the nine months ended September 30, 2021 all remaining limited partnership interests in VX3 were exchanged for shares of our common stock in accordance with the terms of the respective exchange agreement (See Note 10 and Note 15). Vaccinex Products and VX3 were subsequently dissolved as of September 3, 2021 and accordingly no longer are included in the condensed consolidated financial statements. The Company consolidates any VIE of which it is the primary beneficiary. The Company presents its noncontrolling interests as a separate component of stockholders’ equity (deficit). Prior to the exchange of partnership units for common shares (see Note 10) the Company presented the net loss of VX3 equal to the percentage ownership interest retained in such entity by the respective noncontrolling party, and as a separate component within its consolidated statements of operations and comprehensive loss. The financial position of Vaccinex Products and VX3 were not material as of December 31, 2020, and there were no gains or losses for Vaccinex Products or VX3 for the nine month period ended September 30, 2021 and the three and nine month periods ended September 30, 2020. All intercompany transactions and balances have been eliminated.

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information (Accounting Standards Codification (“ASC”) 270, Interim Reporting) and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, these financial statements do not include all of the information necessary for a full presentation of financial position, results of operations, and cash flows in conformity with GAAP. In the opinion of management, the condensed consolidated financial statements reflect all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation of the results of the Company for the periods presented. Intercompany transactions and balances have been fully eliminated in consolidation.

These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on March 31, 2021.

Use of Estimates

These condensed consolidated financial statements have been prepared in conformity with U.S. GAAP. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements and the reported amount of expenses during the reporting period. Such management estimates include those relating to assumptions used in the valuation of stock option awards, and valuation allowances against deferred income tax assets. Actual results could differ from those estimates.

Concentration of Credit Risk, Other Risks and Uncertainties

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. Cash equivalents are deposited in interest-bearing money market accounts. Although the Company deposits its cash with multiple financial institutions, cash balances may occasionally be in excess of the amounts insured by the Federal Deposit Insurance Corporation. Management believes the financial risk associated with these balances is minimal and has not experienced any losses to date.

The Company depends on third-party manufacturers for the manufacture of drug substance and drug product for clinical trials. The Company also relies on certain third parties for its supply chain. Disputes with these third- party manufacturers or shortages in goods or services from third-party suppliers could delay the manufacturing of the Company’s product candidates and adversely impact its results of operations.

Convertible Instruments

The Company applies the accounting standards for derivatives and hedging and for distinguishing liabilities from equity when accounting for hybrid contracts that contain conversion options and other embedded features. The accounting standards require companies to bifurcate embedded features from their host instruments and account for them as free-standing derivative financial instruments according to certain criteria. The criteria include circumstances in which (i) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (ii) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (iii) a separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument.

The Company’s derivative instrument related to certain features embedded within the Company’s 8% Original Issue Discount Senior Secured Convertible Debenture (“the Debenture”) is discussed in Note 9. The derivative is accounted for as a derivative liability and remeasured to fair value as of each balance sheet date and the related remeasurement adjustments are included in interest expense in the Company’s condensed consolidated statement of operations and comprehensive loss, as discussed in Note 4.

Recent Accounting Pronouncements

Recent Accounting Pronouncements Not Yet Adopted

In June 2016, the Financial Accounting Standards Board (“the FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, “Measurement of Credit Losses on Financial Instruments” to improve reporting requirements specific to loans, receivables, and other financial instruments. The new standard requires that credit losses on financial assets measured at amortized cost be determined using an expected loss model, instead of the current incurred loss model, and requires that credit losses related to available-for-sale debt securities be recorded through an allowance for credit losses and limited to the amount by which carrying value exceeds fair value. The new standard also requires enhanced disclosure of credit risk associated with financial assets. The standard is effective for interim and annual periods beginning after December 15, 2022 with early adoption permitted. Based on the composition of the Company’s financial assets, current market conditions and historical credit loss activity, the adoption of this standard is not expected to have a material impact on the Company’s condensed consolidated financial statements.

Accounting Pronouncements Recently Adopted

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) (“ASU 2016-02), which requires a lessee to recognize in its consolidated balance sheet a liability to make lease payments and also a right-of-use asset representing its right to use the underlying asset for the lease term. ASU 2016-02 is effective for the Company for annual periods beginning after December 15, 2020 and interim periods within fiscal years beginning after December 15, 2021, requiring the use of a modified retrospective transition approach. In July 2018, the FASB issued ASU No. 2018-11, Leases, Targeted Improvements to ASC 842, Leases, (“ASU 2018-11”), which contains certain amendments to ASU 2016-02 intended to provide relief in implementing the new standard. ASU 2018-11 provides registrants with an option to not restate comparative periods presented in the financial statements. The Company has elected this new transition approach using the effective date of the standard, for which comparative periods will be presented in accordance with the previous guidance in Accounting Standards Codification (“ASC”) 840, Leases.

The Company has elected to utilize the available package of practical expedients permitted under the transition guidance within the new standard, which does not require the reassessment of the following: (i) whether existing or expired arrangements are or contain a lease, (ii) the lease classification of existing or expired leases, and (iii) whether previous initial direct costs would qualify for capitalization under the new lease standard. Additionally, the Company has made an accounting policy election to keep leases with an initial term of 12 months or less off of its balance sheet.

As an emerging growth company, the Company is not required to reflect the effects of adoption in its consolidated financial statements until it files its annual report for the fiscal year ending December 31, 2021. The Company, however, has evaluated the impact of the new standard on its consolidated financial statements and related disclosures, concluding that the impact will result in the recognition of an operating lease right-of-use asset and corresponding lease obligation on the Company’s consolidated balance sheet as of January 1, 2021 in the amount of approximately $0.3 million, relating to the Company’s lease for its corporate headquarters in Rochester, New York.