NCT07455305

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

The Effect of Simultaneous Versus Sequential Intramuscular Vaccine Injections on Pain Levels in Infants: a Randomized Controlled Trial

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 110 (actual)
• Sponsor: Istanbul University - Cerrahpasa · Academic / Other
• Sex: All
• Age: 12 Months
• Healthy volunteers: Accepted

Summary

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

Detailed description

The study was carried out in the pediatric outpatient vaccination clinic of a private hospital in Istanbul, Türkiye, between 1 September and 15 November 2021. Infants were eligible if they were younger than 12 months, required two routine intramuscular vaccines during the same visit, and were accompanied by a parent or legal guardian able to provide informed consent. Infants were excluded if they had received analgesics within six hours prior to vaccination, received vaccines other than hepatitis B, pentavalent combination vaccine (DTaP-IPV/Hib), or pneumococcal conjugate vaccine, or had known neurological, developmental, or motor impairments. Infants were randomly assigned in a 1:1 ratio to either the simultaneous injection group or the sequential injection group using computer-generated randomization (www.randomizer.org). Allocation was completed prior to the vaccination procedure. A total of 150 infants were assessed for eligibility; 40 did not meet inclusion criteria. The final sample included 110 infants (55 per group). No participants were lost to follow-up.

Conditions

• Injection Pain Prevention
• Injection Pain

Interventions

Type	Name	Description
OTHER	Simultaneous injection	Two trained pediatric nurses administered the vaccines simultaneously into different thighs (vastus lateralis muscles) following a coordinated countdown.
OTHER	Sequential injection	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.

Timeline

• Start date: 2021-09-01
• Primary completion: 2021-11-15
• Completion: 2021-11-15
• First posted: 2026-03-06
• Last updated: 2026-03-06

Locations

1 site across 1 country: Turkey (Türkiye)