Seropersistence of SII-ChAdOx1 NCoV-19 (COVID-19 Vaccine): 6-month Follow-up of a Randomized, Controlled, Observer-blind, Phase 2/3 Immuno-bridging Study in Indian Adults

AZD1222 (ChAdOx1 nCoV-19) is a replication-deficient adenoviral vectored coronavirus disease-19 (COVID-19) vaccine that is manufactured as SII-ChAdOx1 nCoV-19 by the Serum Institute of India Pvt Ltd following technology transfer from Oxford University/AstraZeneca. The non-inferiority of SII-ChAdOx1 nCoV-19 with AZD1222 was previously demonstrated in an observer-blind, phase 2/3 immuno-bridging study (trial registration: CTRI/2020/08/027170). In this analysis of immunogenicity and safety data 6 months post first vaccination (Day 180), 1,601 participants were randomized 3:1 to SII-ChAdOx1 nCoV-19 or AZD1222 (immunogenicity/reactogenicity cohort = 401) and 3:1 to SII-ChAdOx1 nCoV-19 or placebo (safety cohort = 1,200). Immunogenicity was measured by anti-severe acute respiratory syndrome coronavirus 2 spike (anti-S) binding immunoglobulin G and neutralizing antibody (nAb) titers. A decline in anti-S titers was observed in both vaccine groups, albeit with a greater decline in SII-ChAdOx1 nCoV-19 vaccinees (geometric mean titer [GMT] ratio [95% confidence interval (CI) of SII-ChAdOx1 nCoV-19 to AZD1222]: 0.60 [0.41-0.87]). Consistent similar decreases in nAb titers were observed between vaccine groups (GMT ratio [95% CI]: 0.88 [0.44-1.73]). No cases of severe COVID-19 were reported following vaccination, while one case was observed in the placebo group. No causally related serious adverse events were reported through 180 days. No thromboembolic or autoimmune adverse events of special interest were reported. Collectively, these data illustrate that SII-ChAdOx1 nCoV-19 maintained a high level of immunogenicity 6 months post-vaccination. SII-ChAdOx1 nCoV-19 was safe and well tolerated.

Citing Articles

Effects of traditional Chinese exercises or their integration with medical treatments on cognitive impairment: a network meta-analysis based on randomized controlled trials.

Qiu J, Kim S Front Aging Neurosci. 2024; 16:1475406.

PMID: 39588513 PMC: 11586772. DOI: 10.3389/fnagi.2024.1475406.

References

Munro A, Janani L, Cornelius V, Aley P, Babbage G, Baxter D . Safety and immunogenicity of seven COVID-19 vaccines as a third dose (booster) following two doses of ChAdOx1 nCov-19 or BNT162b2 in the UK (COV-BOOST): a blinded, multicentre, randomised, controlled, phase 2 trial. Lancet. 2021; 398(10318):2258-2276. PMC: 8639161. DOI: 10.1016/S0140-6736(21)02717-3. View

Yang W, Shaman J . COVID-19 pandemic dynamics in India, the SARS-CoV-2 Delta variant and implications for vaccination. J R Soc Interface. 2022; 19(191):20210900. PMC: 9169547. DOI: 10.1098/rsif.2021.0900. View

Favresse J, Bayart J, Mullier F, Elsen M, Eucher C, Van Eeckhoudt S . Antibody titres decline 3-month post-vaccination with BNT162b2. Emerg Microbes Infect. 2021; 10(1):1495-1498. PMC: 8300930. DOI: 10.1080/22221751.2021.1953403. View

Griffante G, Chandel S, Ferrante D, Caneparo V, Capello D, Bettio V . Persistence of Neutralizing Antibodies to SARS-CoV-2 in First Wave Infected Individuals at Ten Months Post-Infection: The UnIRSA Cohort Study. Viruses. 2021; 13(11). PMC: 8620452. DOI: 10.3390/v13112270. View

Falsey A, Sobieszczyk M, Hirsch I, Sproule S, Robb M, Corey L . Phase 3 Safety and Efficacy of AZD1222 (ChAdOx1 nCoV-19) Covid-19 Vaccine. N Engl J Med. 2021; 385(25):2348-2360. PMC: 8522798. DOI: 10.1056/NEJMoa2105290. View

Khoury D, Cromer D, Reynaldi A, Schlub T, Wheatley A, Juno J . Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection. Nat Med. 2021; 27(7):1205-1211. DOI: 10.1038/s41591-021-01377-8. View

Sobieszczyk M, Maaske J, Falsey A, Sproule S, Robb M, Frenck Jr R . Durability of protection and immunogenicity of AZD1222 (ChAdOx1 nCoV-19) COVID-19 vaccine over 6 months. J Clin Invest. 2022; 132(18). PMC: 9479753. DOI: 10.1172/JCI160565. View

Chan P, Lui G, Hachim A, Ko R, Boon S, Li T . Serologic Responses in Healthy Adult with SARS-CoV-2 Reinfection, Hong Kong, August 2020. Emerg Infect Dis. 2020; 26(12):3076-3078. PMC: 7706979. DOI: 10.3201/eid2612.203833. View

Andrews N, Tessier E, Stowe J, Gower C, Kirsebom F, Simmons R . Duration of Protection against Mild and Severe Disease by Covid-19 Vaccines. N Engl J Med. 2022; 386(4):340-350. PMC: 8781262. DOI: 10.1056/NEJMoa2115481. View

10.

Rose W, Raju R, Babji S, George A, Madhavan R, Leander Xavier J . Immunogenicity and safety of homologous and heterologous booster vaccination of ChAdOx1 nCoV-19 (COVISHIELD™) and BBV152 (COVAXIN®): a non-inferiority phase 4, participant and observer-blinded, randomised study. Lancet Reg Health Southeast Asia. 2023; :100141. PMC: 9870748. DOI: 10.1016/j.lansea.2023.100141. View

11.

Jo D, Minn D, Lim J, Lee K, Kang Y, Choe K . Rapidly Declining SARS-CoV-2 Antibody Titers within 4 Months after BNT162b2 Vaccination. Vaccines (Basel). 2021; 9(10). PMC: 8539465. DOI: 10.3390/vaccines9101145. View

12.

To K, Hung I, Ip J, Chu A, Chan W, Tam A . Coronavirus Disease 2019 (COVID-19) Re-infection by a Phylogenetically Distinct Severe Acute Respiratory Syndrome Coronavirus 2 Strain Confirmed by Whole Genome Sequencing. Clin Infect Dis. 2020; 73(9):e2946-e2951. PMC: 7499500. DOI: 10.1093/cid/ciaa1275. View

13.

Feng S, Phillips D, White T, Sayal H, Aley P, Bibi S . Correlates of protection against symptomatic and asymptomatic SARS-CoV-2 infection. Nat Med. 2021; 27(11):2032-2040. PMC: 8604724. DOI: 10.1038/s41591-021-01540-1. View

14.

Barouch D, Stephenson K, Sadoff J, Yu J, Chang A, Gebre M . Durable Humoral and Cellular Immune Responses 8 Months after Ad26.COV2.S Vaccination. N Engl J Med. 2021; 385(10):951-953. PMC: 8314733. DOI: 10.1056/NEJMc2108829. View

15.

Kulkarni P, Gunale B, Kohli S, Lalwani S, Tripathy S, Kar S . A Phase 3, randomized, non-inferiority study of a heterologous booster dose of SARS CoV-2 recombinant spike protein vaccine in adults. Sci Rep. 2023; 13(1):16579. PMC: 10547846. DOI: 10.1038/s41598-023-43578-w. View

16.

Gopinath S, Ishak A, Dhawan N, Poudel S, Shrestha P, Singh P . Characteristics of COVID-19 Breakthrough Infections among Vaccinated Individuals and Associated Risk Factors: A Systematic Review. Trop Med Infect Dis. 2022; 7(5). PMC: 9144541. DOI: 10.3390/tropicalmed7050081. View

17.

Voysey M, Clemens S, Madhi S, Weckx L, Folegatti P, Aley P . Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials. Lancet. 2021; 397(10277):881-891. PMC: 7894131. DOI: 10.1016/S0140-6736(21)00432-3. View

18.

Feikin D, Abu-Raddad L, Andrews N, Davies M, Higdon M, Orenstein W . Assessing vaccine effectiveness against severe COVID-19 disease caused by omicron variant. Report from a meeting of the World Health Organization. Vaccine. 2022; 40(26):3516-3527. PMC: 9058052. DOI: 10.1016/j.vaccine.2022.04.069. View

19.

Zhu L, Xu X, Zhu B, Guo X, Xu K, Song C . Kinetics of SARS-CoV-2 Specific and Neutralizing Antibodies over Seven Months after Symptom Onset in COVID-19 Patients. Microbiol Spectr. 2021; 9(2):e0059021. PMC: 8557935. DOI: 10.1128/Spectrum.00590-21. View

20.

Kulkarni P, Padmapriyadarsini C, Vekemans J, Bavdekar A, Gupta M, Kulkarni P . A phase 2/3, participant-blind, observer-blind, randomised, controlled study to assess the safety and immunogenicity of SII-ChAdOx1 nCoV-19 (COVID-19 vaccine) in adults in India. EClinicalMedicine. 2021; 42:101218. PMC: 8629682. DOI: 10.1016/j.eclinm.2021.101218. View