ChAdOx1-S [recombinant]

Trade Name ChAdOx1-S [recombinant]
Generic AstraZeneca COVID-19 Vaccine
AstraZeneca COVID-19 Vaccine Other Names AZD-1222, AZD1222, ChAdOx1 nCoV-19, ChAdOx1-S [recombinant], Coronavirus Disease (COVID-19) vaccine ChAdOx1 nCoV-19, Covishield
Groups Approved, Investigational
Therapeutic Class
Available Country
Last Updated: September 19, 2023 at 7:00 am

ChAdOx1-S [recombinant]

The ChAdOx1-S [recombinant] (previously known as ChAdOx1 nCoV-19 or AZD1222) is one of several vaccines developed in 2020 for the prevention of COVID-19 caused by SARS-CoV-2. The ChAdOx1 viral vector was developed at the University of Oxford and has been investigated as a potential vector for vaccines against another human coronavirus, Middle Eastern respiratory syndrome coronavirus (MERS-CoV). The ChAdOx1 nCoV-19 vaccine, produced in a partnership between The University of Oxford's Jenner Institute and Italian pharmaceutical manufacturer Advent Srl, consists of a replication-deficient adenovirus capable of producing the spike (S) protein of SARS-CoV-2, allowing for the formation of endogenous antibodies against these proteins and, consequently, against SARS-CoV-2. The University of Oxford struck a development and distribution deal with AstraZeneca in May 2020 which paved the way for the vaccine's subsequent approval and usage in dozens of regions across the globe, including Canada, Mexico, the UK, the EU, and Australia, amongst others.

In March 2021, several EU member countries halted the administration of AstraZeneca's COVID-19 Vaccine due to signals of an increased risk of blood clots associated with thrombocytopenia, including the development of cerebral venous sinus thrombosis (CVST). Upon review, the European Medicines Agency (EMA) determined that the vaccine was not associated with a higher overall risk of blood clots, but that it may be associated with very rare instances of blood clots in association with thrombocytopenia - a causal link with the vaccine has not been proven, but is possible and requires further analysis. Despite these concerns, the EMA concluded its review by reiterating that the benefits of the vaccine in the prevention of COVID-19 - a condition which itself leads to blood clots - continue to outweigh the risks associated with its administration.

A phase I/II single-blinded, randomized, placebo-controlled trial to investigate the safety, efficacy, and immunogenicity of the vaccine began in April 2020 with an expected completion date of October 2021. The trial is taking place in the UK, where the vaccine will be administered intramuscularly to healthy adult volunteers between the ages of 18 and 55.


ChAdOx1-S [recombinant] is a two-dose replication-deficient adenovirus vector vaccine used to prevent COVID-19 caused by SARS-CoV-2.

The ChAdOx1-S [recombinant] is indicated for the active immunization of individuals 18 years of age and older for the prevention of COVID-19.

ChAdOx1-S [recombinant] is also used to associated treatment for these conditions: Coronavirus Disease 2019 (COVID‑19)

How ChAdOx1-S [recombinant] works

The ChAdOx1-S [recombinant] is a replication-deficient (i.e. inactivated) chimpanzee adenovirus vector - specifically the ChAdOx1 vector - encoding a trimeric pre-fusion form of the SARS-CoV-2 spike (S) protein. Following intramuscular administration these spike proteins are expressed locally, allowing the immune system to mount a neutralizing antibody/cellular immune response. This initial exposure and priming of the immune system subsequently provides protection against future infection.

ChAdOx1-S [recombinant]


There are no direct data regarding overdosage with this vaccine - in the event of overdosage, prescribing information recommends supportive and symptomatic treatment.

Innovators Monograph

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