• Vaccine Name: Oxford-AstraZeneca COVID-19 vaccine
• Target Pathogen: SARS-CoV-2
• Target Disease: COVID-19
• Product Name: ChAdOx1 nCoV19 vaccine
• Tradename: AZD1222
• Manufacturer: AstraZeneca
• Vaccine Ontology ID: VO_0005158
• CDC CVX code: 210
• CDC CVX description: SARS-COV-2 (COVID-19) vaccine, vector non-replicating, recombinant spike protein-ChAdOx1, preservative free, 0.5 mL
• Type: Recombinant vector vaccine
• Status: Clinical trial
• Host Species for Licensed Use: Human
• Antigen: SARS-CoV-2 spike protein (Folegatti et al., 2020)
• Immunization Route: Intramuscular injection (i.m.)
• Description: A chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19) expressing the SARS-CoV-2 spike protein (Folegatti et al., 2020)

Macaque Response

• Vaccination Protocol: Six animals per group were vaccinated using a prime-only regimen (28 days before challenge) or a prime–boost regimen (56 and 28 days before challenge) intramuscularly with 2.5 × 1010 ChAdOx1 nCoV-19 virus particles each. As a control, six animals were vaccinated via the same route with the same dose of ChAdOx1 GFP. (van et al., 2020)
• Immune Response: Spike-specific antibodies were present as early as 14 days after vaccination and were significantly increased after the second immunization. Endpoint IgG titres of 400–6,400 (prime) and 400–19,200 (prime–boost) were measured on the day of challenge. Virus-specific neutralizing antibodies were also significantly increased after secondary immunization and detectable in all vaccinated animals before challenge (5–40 (prime) and 10–160 (prime–boost)), whereas no virus-specific neutralizing antibodies were detected in control animals. IgM antibodies were present in the serum after vaccination on the day of the challenge in six out of six prime–boost and two out of six prime-only animals. SARS-CoV-2 spike-specific T cell responses were detected on the day of challenge. No statistically significant difference in the magnitude of the response was found between the prime–boost and prime-only group. Vaccination with ChAdOx1 nCoV-19 resulted in the induction of neutralizing antibodies against the vaccine vector itself within 28 days of vaccination. A boost vaccination with ChAdOx1 nCoV-19 resulted in a significant increase in binding and neutralizing antibodies in NHPs and an increase in the SARS-CoV-2 virus-neutralizing titre was not significantly correlated with the ChAdOx1 virus-neutralizing titre. (van et al., 2020)
• Side Effects: No adverse events were observed after vaccination. (van et al., 2020)
• Challenge Protocol: Rhesus macaques were challenged with a 50% tissue culture infective dose (TCID50) of 2.6 × 106 of SARS-CoV-2 in both the upper and lower respiratory tracts.
• Efficacy: Viral gRNA and sgRNA were detected in only two vaccinated animals on 3 d.p.i., and the viral load was significantly lower. Viral gRNA was detected in nose swabs from all animals and no difference was found on any day between vaccinated and control animals. Viral sgRNA was detected in a minority of samples, with no difference between groups. Infectious virus could only be detected at 1 and 3 d.p.i. in prime-only vaccinated and control animals, and 1 d.p.i. in prime–boost vaccinated animals. (van et al., 2020)

Human Response

• Vaccination Protocol: Healthy adults aged 18-55 years with no history of laboratory confirmed SARS-CoV-2 infection or of COVID-19-like symptoms were randomly assigned (1:1) to receive ChAdOx1 nCoV-19 at a dose of 5 × 1010 viral particles or MenACWY as a single intramuscular injection. A protocol amendment in two of the five sites allowed prophylactic paracetamol to be administered before vaccination. Ten participants assigned to a non-randomised, unblinded ChAdOx1 nCoV-19 prime-boost group received a two-dose schedule, with the booster vaccine administered 28 days after the first dose. (Folegatti et al., 2020)
• Immune Response: In the ChAdOx1 nCoV-19 group, spike-specific T-cell responses peaked on day 14 (median 856 spot-forming cells per million peripheral blood mononuclear cells, IQR 493-1802; n=43). Anti-spike IgG responses rose by day 28 (median 157 ELISA units [EU], 96-317; n=127), and were boosted following a second dose (639 EU, 360-792; n=10). Neutralising antibody responses against SARS-CoV-2 were detected in 32 (91%) of 35 participants after a single dose when measured in MNA80 and in 35 (100%) participants when measured in PRNT50. After a booster dose, all participants had neutralising activity (nine of nine in MNA80 at day 42 and ten of ten in Marburg VN on day 56). Neutralising antibody responses correlated strongly with antibody levels measured by ELISA (R2=0·67 by Marburg VN; p<0·001). (Folegatti et al., 2020)
• Side Effects: Local and systemic reactions were more common in the ChAdOx1 nCoV-19 group and many were reduced by use of prophylactic paracetamol, including pain, feeling feverish, chills, muscle ache, headache, and malaise (all p<0·05). There were no serious adverse events related to ChAdOx1 nCoV-19. (Folegatti et al., 2020)