Commitments and Contingencies	12 Months Ended
Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	17. Commitments and Contingencies License Obligations PER.C6 Cell Line - Janssen Vaccines & Prevention B.V. The Company has a royalty-bearing, worldwide non-exclusive license agreement with Janssen Vaccines & Prevention B.V. (formerly known as Crucell Holland B.V.) (“Janssen”) for use of its vaccine technology. The Company may terminate the license agreement without cause, and the agreement contains customary provisions for either party to terminate prior to the expiration of the agreement. The amended license agreement expires on a product-by-product and country-by-country basis on the later of the date upon which the last of the licensed patents applicable to the relevant product expires or 15 years from the date of first commercial sale of the relevant product. The Janssen patent rights include patents issued in the United States with an expected expiration date no earlier than April 2020, in each case not giving effect to any potential extensions and assuming payment of all associated fees. Upon expiration of the amended license agreement, or if the Company terminates the amended license agreement for Janssen’s material breach, the Company retains the right to exploit the rights granted. Under the agreement, the Company is required to pay an annual license fee and annual royalty fees upon reaching certain milestones in an amount that equals the greater of a low single digit percentage of net sales or $150,000. On April 2, 2020, the Company entered into Amendment No. 3 to the Second Restated License Agreement and additionally entered into Amendment No. 4, 5 and 6 throughout 2020 (collectively, the “Amendments”), by and between the Company and Janssen (as amended by Amendment No. 1 to Second Restated License Agreement and Amendment No. 2 to Second Restated License Agreement, together with the Amendments, the “License Agreement”). Pursuant to the Amendment, the field of licenses granted to the Company for the use of the PER.C6 cell line under the License Agreement is expanded to cover COVID-19 caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), in addition to the existing licenses related to Bacillus anthracis and influenza virus. All capitalized terms not defined herein shall have the meanings assigned to them in the Amendment or the License Agreement, as applicable. Pursuant to the Amendment, the Company agreed to pay certain additional development-based milestone payments through approval of licensed products by the FDA for the treatment or prevention of COVID-19, up to an aggregate amount of $1.2 million. The Company also agreed to pay royalty payments as a percentage of net sales of products to a royalty stacking reduction and minimum annual royalty payments, until the expiration of the term of the License Agreement, as amended. Fees incurred under the Janssen agreement totaled $0.2 million and $0.3 million for the years ended December 31, 2021 and 2020, respectively, and are included in research and development expenses in the accompanying consolidated statements of operations and comprehensive loss. Spitfire Acquisition As disclosed in Note 8, the Company is obligated to make payments of up to $80.0 million upon the achievement of specified worldwide net sales of all products developed using the technology acquired from Spitfire Pharma Inc. within ten years following the approval of a new drug application filed with the FDA. Litigation In December 2019, a complaint was filed by Dr. De-Chu Christopher Tang (“Plaintiff”) against the Company, which the Company removed to the United States District Court for the Eastern District of Texas. The Plaintiff amended the complaint in February 2020 to include Vipin K. Garg and David J. Drutz as defendants, in addition to the Company (Dr. Garg, Dr. Drutz, and the Company are collectively referred to as “Defendants”). In March 2020 the Defendants filed a motion to dismiss the complaint. The Court denied the motion without prejudice and allowed Plaintiff an opportunity to file an amended complaint. Plaintiff’s second amended complaint was filed on April 17, 2020, and Defendants filed a motion to dismiss that complaint on May 1, 2020. A hearing on Defendants’ motion to dismiss was held on May 20, 2020. Plaintiff, who is representing himself, alleges five causes of action as follows: (1) Defendants’ alleged retention of Plaintiff’s lab notebooks after the termination of his employment in 2012; (2) alleged plagiarism based on publishing an article without naming Plaintiff as an author; (3) use of the Adhigh System, which Plaintiff alleges he developed; (4) allegations that Defendants manipulated the Company’s stock and caused a decrease in value; and (5) allegations that the Defendants “wast[ed] government grant money and poison[ed] science by leaving data to rot.” On September 30, 2020, Plaintiff filed a motion titled “Motion to Proscribe Defendants’ Allegedly Illegal Use of Plaintiff’s AdHigh System in Altimmune’s Human Clinical Trials,” to which Defendants filed an opposition on October 13, 2020. The court has not yet ruled on that motion, which also remains pending. On November 6, 2020, Defendants filed a motion for summary judgment on the basis of lack of personal jurisdiction, insufficient service of process, and failure to state a claim. The court ruled on that motion on March 25, 2021, which dismissed the case on the basis of lack of personal jurisdiction. On December 1, 2020, the magistrate judge assigned to the case issued a report and recommendation that Defendants’ motion to dismiss of May 1, 2020 be granted and that this action be dismissed for lack of personal jurisdiction. Plaintiff filed objections to the report and recommendation on December 14, 2020, and the resolution of those objections by the district court remains pending. In December 2021, the Plaintiff refiled the complaint in the United States District Court for the District of Maryland. The Company believes the allegations in the complaint are without merit and intends to vigorously defend the litigation. However, the outcome of this legal proceeding is uncertain at this time and the Company cannot reasonably estimate a range of loss, if any. Accordingly, the Company has not accrued any liability associated with this action. The Company is a party in various contracts and subject to disputes, litigation, and potential claims arising in the ordinary course of business none of which are currently reasonably possible or probable of material loss.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

17. Commitments and Contingencies

License Obligations

PER.C6 Cell Line - Janssen Vaccines & Prevention B.V.

The Company has a royalty-bearing, worldwide non-exclusive license agreement with Janssen Vaccines & Prevention B.V. (formerly known as Crucell Holland B.V.) (“Janssen”) for use of its vaccine technology. The Company may terminate the license agreement without cause, and the agreement contains customary provisions for either party to terminate prior to the expiration of the agreement. The amended license agreement expires on a product-by-product and country-by-country basis on the later of the date upon which the last of the licensed patents applicable to the relevant product expires or 15 years from the date of first commercial sale of the relevant product. The Janssen patent rights include patents issued in the United States with an expected expiration date no earlier than April 2020, in each case not giving effect to any potential extensions and assuming payment of all associated fees. Upon expiration of the amended license agreement, or if the Company terminates the amended license agreement for Janssen’s material breach, the Company retains the right to exploit the rights granted. Under the agreement, the Company is required to pay an annual license fee and annual royalty fees upon reaching certain milestones in an amount that equals the greater of a low single digit percentage of net sales or $150,000.

On April 2, 2020, the Company entered into Amendment No. 3 to the Second Restated License Agreement and additionally entered into Amendment No. 4, 5 and 6 throughout 2020 (collectively, the “Amendments”), by and between the Company and Janssen (as amended by Amendment No. 1 to Second Restated License Agreement and Amendment No. 2 to Second Restated License Agreement, together with the Amendments, the “License Agreement”). Pursuant to the Amendment, the field of licenses granted to the Company for the use of the PER.C6 cell line under the License Agreement is expanded to cover COVID-19 caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), in addition to the existing licenses related to Bacillus anthracis and influenza virus. All capitalized terms not defined herein shall have the meanings assigned to them in the Amendment or the License Agreement, as applicable.

Pursuant to the Amendment, the Company agreed to pay certain additional development-based milestone payments through approval of licensed products by the FDA for the treatment or prevention of COVID-19, up to an aggregate amount of $1.2 million. The Company also agreed to pay royalty payments as a percentage of net sales of products to a royalty stacking reduction and minimum annual royalty payments, until the expiration of the term of the License Agreement, as amended. Fees incurred under the Janssen agreement totaled $0.2 million and $0.3 million for the years ended December 31, 2021 and 2020, respectively, and are included in research and development expenses in the accompanying consolidated statements of operations and comprehensive loss.

Spitfire Acquisition

As disclosed in Note 8, the Company is obligated to make payments of up to $80.0 million upon the achievement of specified worldwide net sales of all products developed using the technology acquired from Spitfire Pharma Inc. within ten years following the approval of a new drug application filed with the FDA.

Litigation

In December 2019, a complaint was filed by Dr. De-Chu Christopher Tang (“Plaintiff”) against the Company, which the Company removed to the United States District Court for the Eastern District of Texas. The Plaintiff amended the complaint in February 2020 to include Vipin K. Garg and David J. Drutz as defendants, in addition to the Company (Dr. Garg, Dr. Drutz, and the Company are collectively referred to as “Defendants”). In March 2020 the Defendants filed a motion to dismiss the complaint. The Court denied the motion without prejudice and allowed Plaintiff an opportunity to file an amended complaint. Plaintiff’s second amended complaint was filed on April 17, 2020, and Defendants filed a motion to dismiss that complaint on May 1, 2020. A hearing on Defendants’ motion to dismiss was held on May 20, 2020. Plaintiff, who is representing himself, alleges five causes of action as follows: (1) Defendants’ alleged retention of Plaintiff’s lab notebooks after the termination of his employment in 2012; (2) alleged plagiarism based on publishing an article without naming Plaintiff as an author; (3) use of the Adhigh System, which Plaintiff alleges he developed; (4) allegations that Defendants manipulated the Company’s stock and caused a decrease in value; and (5) allegations that the Defendants “wast[ed] government grant money and poison[ed] science by leaving data to rot.” On September 30, 2020, Plaintiff filed a motion titled “Motion to Proscribe Defendants’ Allegedly Illegal Use of Plaintiff’s AdHigh System in Altimmune’s Human Clinical Trials,” to which Defendants filed an opposition on October 13, 2020. The court has not yet ruled on that motion, which also remains pending. On November 6, 2020, Defendants filed a motion for summary judgment on the basis of lack of personal jurisdiction, insufficient service of process, and failure to state a claim. The court ruled on that motion on March 25, 2021, which dismissed the case on the basis of lack of personal jurisdiction. On December 1, 2020, the magistrate judge assigned to the case issued a report and recommendation that Defendants’ motion to dismiss of May 1, 2020 be granted and that this action be dismissed for lack of personal jurisdiction. Plaintiff filed objections to the report and recommendation on December 14, 2020, and the resolution of those objections by the district court remains pending. In December 2021, the Plaintiff refiled the complaint in the United States District Court for the District of Maryland. The Company believes the allegations in the complaint are without merit and intends to vigorously defend the litigation. However, the outcome of this legal proceeding is uncertain at this time and the Company cannot reasonably estimate a range of loss, if any. Accordingly, the Company has not accrued any liability associated with this action.

The Company is a party in various contracts and subject to disputes, litigation, and potential claims arising in the ordinary course of business none of which are currently reasonably possible or probable of material loss.