Last reviewed 2026-04-22 · How we verify

TT

TT is a recombinant adenovirus type 5 vector-based vaccine that expresses the SARS-CoV-2 spike protein to elicit immune responses against COVID-19.

TT is a recombinant adenovirus type 5 vector-based vaccine that expresses the SARS-CoV-2 spike protein to elicit immune responses against COVID-19. Used for COVID-19 prevention (marketed in multiple countries).

At a glance

Mechanism of action

TT (also known as Convidecia or Ad5-nCoV) uses a replication-incompetent adenovirus serotype 5 as a viral vector to deliver genetic instructions for producing the SARS-CoV-2 spike protein. This triggers both cellular and humoral immune responses, enabling the body to recognize and neutralize the virus upon exposure. The vaccine can be administered as a single dose or in a prime-boost regimen.

Approved indications

• COVID-19 prevention (marketed in multiple countries)

Common side effects

• Injection site pain or swelling
• Fever
• Fatigue
• Headache
• Myalgia

Key clinical trials

• Teletherapy in Children Who Are Deaf and Hard of Hearing (NA)
• IT-TT as an Effective and Well-Tolerated Strategy for CNS Prop in High-Risk DLBCL: a Prospective Ph II Study (PHASE2)
• FLuorometholone as Adjunctive MEdical Therapy for TT Surgery (FLAME) Trial (PHASE3)
• Study on the Efficacy and Safety of the TmBU Conditioning Regimen in High-risk or Relapsed/Refractory Acute Leukemia (PHASE2)
• Non-Invasive Spinal Cord Stimulation After Injury (NA)
• AI-Driven Digital Self-Assessment Framework for Preclinical Tooth Preparation (NA)
• Long-term Safety, Tolerability and Effectiveness Study of Ofatumumab in Patients With Relapsing MS (PHASE3)
• Hemithyroidectomy or Total-Thyroidectomy in 'Low-risk' Thyroid Cancers (NA)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.