A 6-month-old male infant from Delhi is brought to the immunization clinic for his routine vaccination. The health worker notes that the vaccine vial of pentavalent (DPT-HepB-Hib) was opened 4 hours ago at room temperature (28°C) and has been stored on the shelf without a vaccine vial monitor (VVM). The vial has no visible cracks or contamination. The health worker is unsure whether the vaccine can still be used. According to WHO and Indian immunization guidelines, what is the most appropriate action?