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Table 1 Characteristics of included studies

From: Immunogenicity and clinical features relating to BNT162b2 messenger RNA COVID-19 vaccine, Ad26.COV2.S and ChAdOx1 adenoviral vector COVID-19 vaccines: a systematic review of non-interventional studies

Authors

Study design

Study participants

Sample size

Time from vaccination to onset of symptoms (Days)

Findings

Limitations

Parry et al. 2021 [8]

Observational

Older adults (80–99-years-old)

165

-

Antibody response in a large majority

Enhanced T-cells response in ChAdOx1 than in BNT162b2 mRNA recipients

Small sample size

Not peer-reviewed (as at the time of this review)

Muller et al. 2021 [9]

Observational

Older persons (≥ 60-years-old)

176

-

After 2 doses of BTN162b2 mRNA vaccine, SARS-CoV-2 spike protein specific IgG antibody was lower in older persons (> 80-years-old)

Detectable neutralising antibody titre was absent in many older persons, compared to younger persons

Small sample size

Scully et al. 2021 [15]

Observational

 

23

6 – 24 days after vaccination with ChAdOx1

Vaccine-induced immune thrombotic thrombocytopeania (VITT) after ChAdOx1 vaccine

Presence of Platelet Factor 4 (PF4)

Potential risk of ascertainment bias in associating adverse events with vaccination

Shultz et al. 2021 [17]

Observational

Persons of 32–52-years-old

5

7 – 10 days after vaccination with ChAdOx1

Suggests a possible development of vaccine-induced immune thrombotic thrombocytopenia after ChAdOx1 vaccine

Presence of Platelet Factor 4 (PF4)

Potential risk of ascertainment bias

Greinacher et al. 2021 [18]

Observational

Persons from Austria and Germany

11

5 -16 days of vaccination ChAdOx1

Development of immune thrombotic thrombocytopenia (ITT) after vaccination with ChAdOx1 nCov-19

Seen mostly in females

Highly elevated D-dimer levels and low fibrinogen

Potential risk of ascertainment bias. Potential under-reporting of cases following passive surveillance

Yocum et al. 2021 [19]

Case report

A 62-year-old female

1

37 days of vaccination with Ad26.COV2-S

Low fibrinogen, low platelets and negative tests for PF4 (37 days after Ad26.COV2-S vaccine administration)

Suspected vaccine-induced thrombotic thrombocytopenia

Potential risk of ascertainment bias

Blauenfeldt et al. 2021 [21]

Case report

A 60-year-old woman

1

7 days of vaccination with ChAdOx1

Presence of IgG platelet factor 4. increase in D-dimer, thrombocytopenia and haemorrhage

Potential risk of ascertainment bias

Wolf et al. 2021 [22]

Case series

Women between 22 and 46-years-old

3

4 – 17 days after vaccination with ChAdOx1

Elevated D-dimer, Presence of IgG platelet factor 4, presence of SARS-CoV-2 spike IgG

Potential risk of ascertainment bias

See et al. 2021 [23]

Case series

Women of 18–< 60-years-old

12

6 – 15 days after vaccination with Ad26.COV2.S

Positive results for Heparin–platelet factor 4 antibody, abnormal levels of D-dimer and fibrinogen, thrombocytopenia and haemorrhage

Potential risk of incomplete data from retrospective data collection