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Immune responses to a single dose of the AZD1222/Covishield vaccine at 16 weeks in individuals in Sri Lanka (preprint)
medrxiv; 2021.
Preprint
in English
| medRxiv | ID: ppzbmed-10.1101.2021.07.26.21261122
ABSTRACT
Introduction:
Due to limited access to vaccines, many countries have only administered a single dose of the AZD1222, while the dosage intervals have increased [≥] weeks. We sought to investigate the immunogenicity of a single dose of vaccine at [≥] 16 weeks.Methods:
SARS-CoV-2 specific antibodies in 553 individuals and antibodies to the receptor binding domain (RBD) of the Wuhan virus (WT) and the variants of concern (VOCs), ACE2 receptor blocking antibodies, ex vivo and cultured IFN{gamma} T cell responses and B cell ELISpot responses were investigated in a sub-cohort.Results:
The seropositivity rates in those >70 years of age (93.7%) was not significantly different compared to other age groups (97.7 to 98.2, Pearson Chi-Square = 7.8, p-value = 0.05). The antibody titres (antibody index) significantly declined (p<0.0001) with increase in age. 18/69 (26.1%) of individuals did not have ACE2 receptor blocking antibodies, while responses to the RBD of WT (p=0.03), B.1.1.7 (p=0.04) and B.1.617.2 (p=0.02) were significantly lower in those who were >60 years. Ex vivo IFN {gamma} T cell ELISpot responses were seen in 10/66 (15.1%), while only a few expressed CD107a. However, >85% had a high frequency of cultured IFN{gamma} T cell ELISpot responses and B cell ELISpots.Conclusion:
Virus specific antibodies were maintained at [≥] 16 weeks after receiving a single dose of AZD1222, although levels were lower to VOCs, especially in older individuals. A single dose induced a high frequency of memory T and B cell responses.
Full text:
Available
Collection:
Preprints
Database:
medRxiv
Main subject:
Memory Disorders
Language:
English
Year:
2021
Document Type:
Preprint
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