The Effect of Simultaneous Versus Sequential Intramuscular Vaccine Injections on Pain Levels in Infants

NCT07455305 | Completed

• 1 other identifier: IUCerrahpasaRCT
• Study Type: interventional
• Target: 110
• Locations: 1 country
• Sites: 1

Brief Summary

This study was designed as a randomized controlled trial comparing simultaneous and sequential administration of intramuscular vaccines in infants.

Conditions

Injection Pain Prevention; Injection Pain

Keywords

sequential injection; simultaneous injection

Outcome Measures

Primary Outcomes (1)

• Pain was assessed using the FLACC

  The scale has 5 behavioral assessment categories (facial expression, leg movement, activity, crying, consolability). Each category consists of three items and is scored between 0 and 2 points. The total scale score ranges from 0 to10, with higher scores indicating greater pain intensity.

  Time Frame: Baseline; During injection (periprocedural); Immediately after injection (within 1 minute)

Study Arms (2)

Simultaneous injection group

EXPERIMENTAL

Two trained pediatric nurses administered the vaccines simultaneously into different thighs (vastus lateralis muscles) following a coordinated countdown.

Other: Simultaneous injection

Sequential injection group

OTHER

A single nurse administered the two vaccines consecutively into different thighs. A pause of approximately 10-15 seconds between injections allowed the infant to settle. Vaccinations were performed individually in a quiet room to prevent distraction or distress from other children. Infants were positioned on an examination stretcher with the thigh exposed.

Other: Sequential injection

Interventions

Simultaneous injection OTHER

Two trained pediatric nurses administered the vaccines simultaneously into different thighs (vastus lateralis muscles) following a coordinated countdown.

Simultaneous injection group

Sequential injection OTHER

A single nurse administered the two vaccines consecutively into different thighs. A pause of approximately 10-15 seconds between injections allowed the infant to settle.

Sequential injection group

Eligibility Criteria

• Age: Up to 12 Months
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17)

You may qualify if:

• The following criteria were determined: the child was ordered to receive two of the routine childhood IM vaccines (hepatitis B, quintuple combination vaccine, pneumococcal vaccine), the parents were willing to participate in the study, the child had not received painkillers in the last 6 hours, and the child did not have mental and motor retardation.

You may not qualify if:

• It was determined that the child should be 1 year of age or older, the vaccines other than the quintuple mixed vaccine, Pneumococcal vaccine and Hepatitis B vaccine should have been ordered by the physician.

Sponsors & Collaborators

• Istanbul University - Cerrahpasa: lead

Study Sites (1)

Koç University

Istanbul, İ̇stanbul, 34500, Turkey (Türkiye)

Location

Study Officials

• Sevil Inal

  Istanbul University - Cerrahpasa

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: All assessments were performed by the same experienced pediatric nurse who was not part of the research team and was unaware of the study hypotheses.
• Purpose: SUPPORTIVE CARE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: IstanbulUC

Study Record Dates

• First Submitted: February 25, 2026
• First Posted: March 6, 2026
• Study Start: September 1, 2021
• Primary Completion: November 15, 2021
• Study Completion: November 15, 2021
• Last Updated: March 6, 2026

Record last verified: 2026-03

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)