COVID-19; Comparative Study of Serum S-reactive IgG4 Antibody Levels, N-reactive IgG Antibody Levels, and S-reactive IgG Antibody Levels in COVID-19 mRNA Vaccine Recipients and Non-Recipients using IgG Antibody Testing

Comparative study of blood S-reactive IgG4 antibody levels, N-reactive IgG total antibody levels, and S-reactive IgG total antibody levels in IgG antibody tests of Covid19 mRNA vaccine recipients and non-vaccinated individuals

Status

Recruiting

Phases

Early Phase 1

Study type

Observational

Source

JPRN

Registry ID

JPRN-jRCT1030250071

Enrollment

180

Registered

2025-04-30

Start date

2025-04-30

Completion date

Unknown

Last updated

2026-06-29

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

none

Interventions

None listed

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: Japanese people (non-naturalized Japanese nationals) who meet the following requirements. We are looking for 20 people each who have not received the mRNA vaccine and who have received 1 to 8 doses of the mRNA vaccine. 1) Those who have not received the mRNA vaccine: 20 people 2) Those who have received 1 dose of the mRNA vaccine: 20 people 3) Those who have received 2 doses of the mRNA vaccine: 20 people 4) Those who have received 3 doses of the mRNA vaccine: 20 people 5) Those who have received 4 doses of the mRNA vaccine: 20 people 6) Those who have received 5 doses of the mRNA vaccine: 20 people 7) Those who have received 6 doses of the mRNA vaccine: 20 people 8) Those who have received 7 doses of the mRNA vaccine: 20 people 9) Those who have received 8 doses of the mRNA vaccine: 20 people

Exclusion criteria

Exclusion criteria: 1) Non-Japanese. 2) Patients currently participating in other clinical trials, or patients who have participated in a clinical trial in the past and for whom more than one month has not passed since the last dose of the test drug. 3) Patients who are unable to register for this study via online medical consultation or online electronic device, or who are unable to enter data or send it via the Internet, either by themselves or their legal representative. 4) Patients who the principal investigator or co-investigator of the study deems inappropriate as subjects.

Design outcomes

Primary

Measure	Time frame
IgG antibody test: amount of S-reactive IgG4 antibody, N-reactive IgG antibody, and S-reactive IgG antibody in blood	—

Secondary

Measure	Time frame
Measure the incidence of adverse events using CTCAE	—

Contacts

Public ContactHidy Kobayashi

Japan Society of Clinical Study for Frontier-Medicine

cro@jscsf.net+81-3-5542-1597

Outcome results