Government Contracts	12 Months Ended
Dec. 31, 2021
Contractors [Abstract]
Government Contracts	13. Government Contracts BARDA In July 2018, the Company was awarded a contract from Biomedical Advanced Research and Development Authority (“BARDA”) of up to $44.2 million to develop tebipenem HBr for the treatment of complicated urinary tract infections (“cUTI”) caused by antibiotic resistant Gram-negative bacteria and for assessment against biodefense pathogens. The award committed initial funding of $15.7 million over a three-year base period from July 1, 2018 to June 30, 2021 for cUTI development activities. In May 2019, the contract was modified to include additional funding of approximately $2.5 million for the development of tebipenem HBr, increasing the amount of the initial committed funding from $15.7 million to approximately $18.2 million and increasing the overall potential award to $46.8 million. In January 2020, BARDA exercised its first contract option for additional committed funding of $15.9 million, increasing the total committed funding to $34.0 million and extended the period of performance through November 1, 2021. In October 2021, BARDA extended the period of performance for the first contract option through December 15, 2022. As of December 31, 2021, the balance of the award was subject to BARDA exercising a second option which would entail funding of $12.7 million and is exercisable by BARDA subject to, among other things, satisfactory progress and results from the biodefense studies described below. On January 19, 2022, the Company announced that BARDA exercised a new option on the contract. The new option increases the total amount of committed funding by $12.9 million to approximately $46.9 million, increasing the total potential contract value to $59.7 million. The additional $12.9 million option is expected to provide support for a clinical trial and related activities for orally administered tebipenem HBr's use in treating pediatric patients with complicated urinary tract infections, including acute pyelonephritis. As part of an inter-agency collaboration between BARDA and the Defense Threat Reduction Agency (“DTRA”), a series of studies to assess the efficacy of tebipenem HBr in the treatment of infections caused by biodefense threats such as anthrax, plague and melioidosis will be conducted under the direction of Spero. DTRA provides up to $10.0 million, in addition to the total potential award from BARDA, to cover the cost of the nonclinical biodefense aspects of the collaborative program for tebipenem HBr. Together, BARDA and DTRA will provide up to $69.7 million in total funding for the clinical development and biodefense assessment of tebipenem HBr, of which $12.7 million is subject to the exercise of options by BARDA and Spero’s achievement of specified milestones. During the years ended December 31, 2021 and 2020, the Company recognized $9.9 million and $7.9 million of revenue under this agreement, respectively. U.S. Department of Defense On July 1, 2019, the Company received a $5.9 million award from the DoD Congressionally Directed Medical Research Programs (“CDMRP”) Joint Warfighter Medical Research Program. The funding will support the further clinical development of SPR206. The award commits non-dilutive funding of $5.9 million over a four-year period to cover the costs of select Phase 1 pharmacology studies, a 28-day GLP NHP toxicology study, and microbiological surveillance studies that would be required for a potential New Drug Application ("NDA") submission with the FDA for SPR206. During the years ended December 31, 2021 and 2020, the Company recognized $4.5 million and $0.4 million in revenue under this agreement, respectively. NIAID In May 2021, the Company was awarded a five-year contract from the U.S. National Institute of Allergy and Infectious Diseases (“NIAID”) under the Agency’s Omnibus Broad Agency Announcement No. HHS-NIH-NIAID-BAA2020-1 award mechanism to support further development of SPR206. Funding will be used to offset certain expenses related to manufacturing, clinical, non-clinical and regulatory activities. The Company can receive up to $23.4 million over a base period and five option periods. As of December 31, 2021, funding for the base period totaling $2.1 million has been committed. The Company recognized $0.4 million under this agreement during the year ended December 31, 2021. In February 2017, the Company was awarded a grant from the NIAID under its Small Business Innovation Research program, over a two-year period from March 1, 2017 to February 28, 2019 to conduct additional preclinical studies of SPR720, the Company’s novel oral bacterial gyrase inhibitor, for the treatment of non-tuberculous mycobacterial infections. The award was structured as a 12-month $0.6 million base period and a $0.4 million option period. Through December 31, 2017, only the base period funds were committed. In February 2018 NIAID exercised the $0.4 million 12-month option period. In January 2019, the period of performance for this award was extended through February 28, 2020 and during the year ended December 31, 2020, this award was closed out. The Company did not recognize revenue under this agreement during the year ended December 31, 2021 and recognized less than $0.1 million in revenue under this agreement during the year ended December 31, 2020. In June 2016, the Company entered into agreements with Pro Bono Bio PLC (“PBB”), a corporation organized under the laws of England, and certain of its affiliates, including PBB Distributions Limited and Cantab Anti-Infectives Limited (“CAI”), in order to acquire certain intellectual property and government funding arrangements relating to SPR206. Under these agreements, CAI agreed to submit a request to NIAID to novate the then CAI-held NIAID contract to Spero, which was finalized in December 2017. The NIAID contract provides for development funding of up to $6.5 million over a base period and three option periods. As of December 31, 2021, funding for the base period and the first two option periods totaling $5.9 million had been committed. In March 2021, a contract modification was executed and the performance period for this award was extended until June 15, 2021. During the years ended December 31, 2021 and 2020, the Company recognized $0.4 million and $0.7 million in revenue under this agreement, respectively.

Government Contracts

12 Months Ended

Dec. 31, 2021

13. Government Contracts

BARDA

In July 2018, the Company was awarded a contract from Biomedical Advanced Research and Development Authority (“BARDA”) of up to $44.2 million to develop tebipenem HBr for the treatment of complicated urinary tract infections (“cUTI”) caused by antibiotic resistant Gram-negative bacteria and for assessment against biodefense pathogens. The award committed initial funding of $15.7 million over a three-year base period from July 1, 2018 to June 30, 2021 for cUTI development activities. In May 2019, the contract was modified to include additional funding of approximately $2.5 million for the development of tebipenem HBr, increasing the amount of the initial committed funding from $15.7 million to approximately $18.2 million and increasing the overall potential award to $46.8 million. In January 2020, BARDA exercised its first contract option for additional committed funding of $15.9 million, increasing the total committed funding to $34.0 million and extended the period of performance through November 1, 2021. In October 2021, BARDA extended the period of performance for the first contract option through December 15, 2022. As of December 31, 2021, the balance of the award was subject to BARDA exercising a second option which would entail funding of $12.7 million and is exercisable by BARDA subject to, among other things, satisfactory progress and results from the biodefense studies described below. On January 19, 2022, the Company announced that BARDA exercised a new option on the contract. The new option increases the total amount of committed funding by $12.9 million to approximately $46.9 million, increasing the total potential contract value to $59.7 million. The additional $12.9 million option is expected to provide support for a clinical trial and related activities for orally administered tebipenem HBr's use in treating pediatric patients with complicated urinary tract infections, including acute pyelonephritis.

As part of an inter-agency collaboration between BARDA and the Defense Threat Reduction Agency (“DTRA”), a series of studies to assess the efficacy of tebipenem HBr in the treatment of infections caused by biodefense threats such as anthrax, plague and melioidosis will be conducted under the direction of Spero. DTRA provides up to $10.0 million, in addition to the total potential award from BARDA, to cover the cost of the nonclinical biodefense aspects of the collaborative program for tebipenem HBr. Together, BARDA and DTRA will provide up to $69.7 million in total funding for the clinical development and biodefense assessment of tebipenem HBr, of which $12.7 million is subject to the exercise of options by BARDA and Spero’s achievement of specified milestones.

During the years ended December 31, 2021 and 2020, the Company recognized $9.9 million and $7.9 million of revenue under this agreement, respectively.

U.S. Department of Defense

On July 1, 2019, the Company received a $5.9 million award from the DoD Congressionally Directed Medical Research Programs (“CDMRP”) Joint Warfighter Medical Research Program. The funding will support the further clinical development of SPR206. The award commits non-dilutive funding of $5.9 million over a four-year period to cover the costs of select Phase 1 pharmacology studies, a 28-day GLP NHP toxicology study, and microbiological surveillance studies that would be required for a potential New Drug Application ("NDA") submission with the FDA for SPR206. During the years ended December 31, 2021 and 2020, the Company recognized $4.5 million and $0.4 million in revenue under this agreement, respectively.

NIAID

In May 2021, the Company was awarded a five-year contract from the U.S. National Institute of Allergy and Infectious Diseases (“NIAID”) under the Agency’s Omnibus Broad Agency Announcement No. HHS-NIH-NIAID-BAA2020-1 award mechanism to support further development of SPR206. Funding will be used to offset certain expenses related to manufacturing, clinical, non-clinical and regulatory activities. The Company can receive up to $23.4 million over a base period and five option periods. As of December 31, 2021, funding for the base period totaling $2.1 million has been committed. The Company recognized $0.4 million under this agreement during the year ended December 31, 2021.

In February 2017, the Company was awarded a grant from the NIAID under its Small Business Innovation Research program, over a two-year period from March 1, 2017 to February 28, 2019 to conduct additional preclinical studies of SPR720, the Company’s novel oral bacterial gyrase inhibitor, for the treatment of non-tuberculous mycobacterial infections. The award was structured as a 12-month $0.6 million base period and a $0.4 million option period. Through December 31, 2017, only the base period funds were committed. In February 2018 NIAID exercised the $0.4 million 12-month option period. In January 2019, the period of performance for this award was extended through February 28, 2020 and during the year ended December 31, 2020, this award was closed out. The Company did not recognize revenue under this agreement during the year ended December 31, 2021 and recognized less than $0.1 million in revenue under this agreement during the year ended December 31, 2020.

In June 2016, the Company entered into agreements with Pro Bono Bio PLC (“PBB”), a corporation organized under the laws of England, and certain of its affiliates, including PBB Distributions Limited and Cantab Anti-Infectives Limited (“CAI”), in order to acquire certain intellectual property and government funding arrangements relating to SPR206. Under these agreements, CAI agreed to submit a request to NIAID to novate the then CAI-held NIAID contract to Spero, which was finalized in December 2017. The NIAID contract provides for development funding of up to $6.5 million over a base period and three option periods. As of December 31, 2021, funding for the base period and the first two option periods totaling $5.9 million had been committed. In March 2021, a contract modification was executed and the performance period for this award was extended until June 15, 2021. During the years ended December 31, 2021 and 2020, the Company recognized $0.4 million and $0.7 million in revenue under this agreement, respectively.