The effect of different sequences of vaccination against COVID and the flu on protection and safety

Timing and sequence of vaccination against COVID-19 and Influenza - TACTIC

Status

Active, not recruiting

Phases

Phase 4

Study type

Interventional

Source

EU CTR

Registry ID

EUCTR2021-002186-17-NL

Enrollment

160

Registered

2021-04-29

Start date

2021-08-31

Completion date

Unknown

Last updated

2021-12-13

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

Conditions

Immunogenicity of the consecutive vaccination with both an mRNA COVID-19 vaccin and Influenza vaccin, in different sequences

Interventions

Trade Name: Comirnaty Product Name: Comirnaty Pharmaceutical Form: Concentrate and solvent for solution for injection Trade Name: Moderna Product Name: Moderna Pharmaceutical Form: Concentrate and so

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: Age equal to or above 18 years No previous COVID-vaccine Healthy (=no chronic disease or medication use) Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18-64 years) yes F.1.2.1 Number of subjects for this age range 160 F.1.3 Elderly (>=65 years) no F.1.3.1 Number of subjects for this age range

Exclusion criteria

Exclusion criteria: History of COVID-19 infection, confirmed by a microbiological test Vaccinated against influenza in the past 6 months

Design outcomes

Primary

Measure	Time frame
Main Objective: Aim 1. To study the impact of different sequences of combined influenzaand SARS-CoV-2 vaccinations on immunological responses and side effects. Aim 2. To understand the immunological mechanisms that mediate the potential interference between influenza and COVID-19 vaccines, and the long-term effects of this interaction.;Secondary Objective: Not applicable;Primary end point(s): Geometric mean concentrations (GMCs) of RBD- and S-specific IgG, IgA and IgM in serum at 28 days after last vaccination.;Timepoint(s) of evaluation of this end point: 28days after last vaccination	—

Measure

Time frame

Main Objective: Aim 1. To study the impact of different sequences of combined influenzaand SARS-CoV-2 vaccinations on immunological responses and side effects. Aim 2. To understand the immunological mechanisms that mediate the potential interference between influenza and COVID-19 vaccines, and the long-term effects of this interaction.;Secondary Objective: Not applicable;Primary end point(s): Geometric mean concentrations (GMCs) of RBD- and S-specific IgG, IgA and IgM in serum at 28 days after last vaccination.;Timepoint(s) of evaluation of this end point: 28days after last vaccination

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Secondary

Measure	Time frame
Secondary end point(s): Seroconversion of IgG to the SARS-CoV-2 spike protein at day 28 after the first dose of COVID-19 vaccines. - Virus neutralization assays for the standard SARS-CoV-2 variant, as well as for the B1.1.7 and B1.351 variants - IgG, IgA and IgM concentrations against SARS-CoV-2 and influenza antigens in nasal mucosal lining fluid at the various sampling time points. - Specific anti-SARS-CoV-2 T-cell responses against standard SARSCoV- 2 variant, as well as for the B1.1.7 and B1.351 variants - Local reactions at injection site or systemic reactions after vaccination - Serious adverse events and other adverse events;Timepoint(s) of evaluation of this end point: Day 28, day 56, day 84, day 236	—

Measure

Time frame

Secondary end point(s): Seroconversion of IgG to the SARS-CoV-2 spike protein at day 28 after the first dose of COVID-19 vaccines. - Virus neutralization assays for the standard SARS-CoV-2 variant, as well as for the B1.1.7 and B1.351 variants - IgG, IgA and IgM concentrations against SARS-CoV-2 and influenza antigens in nasal mucosal lining fluid at the various sampling time points. - Specific anti-SARS-CoV-2 T-cell responses against standard SARSCoV- 2 variant, as well as for the B1.1.7 and B1.351 variants - Local reactions at injection site or systemic reactions after vaccination - Serious adverse events and other adverse events;Timepoint(s) of evaluation of this end point: Day 28, day 56, day 84, day 236

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Countries

Netherlands

Contacts

Public ContactElisabeth Dulfer

RadboudUMC

elisabeth.dulfer@radboudumc.nl

Outcome results

None listed

Source: EU CTR (via WHO ICTRP) · Data processed: Feb 11, 2026