Pathum SOOKAROMDEE, Viroj WIWANITKIT

1Private Academic Consultant, Bangkok, Thailand;2Department of Community Medicine, Dr.D.Y.Patil University,Pune, Maharashtra, India

Dear Editor,

We would like to share ideas on “Comparison of in-vial exhaust method versus conventional exhaust method in the injection of COVID-19 vaccine.”[1]Xuet al.[1]concluded that“Implementingthein-vialexhaustmethodinthevaccineinjection caneffectivelyreducetheincidenceofsolutionspillage,reduce nucleicacidcontamination,andensurethatthevaccineisinjected attheprescribeddoseandapplicationvalue.[1]” We agree that in-vial method might be appropriate for injection of vaccine.However, an important factor for the success of any method is experience of practitioner.Attempt to reduce vaccine waste is good but we should concern on the possible contamination as well.Whether the in-vial exhaustion can result in a contamination or not is an issue for further investigation.Finally, quantitation accuracy is another important topic.How the two different techniques relate to syringe dead space is an interesting issue for further study.[2]

A reply from authors Xuet al.[1]of the commented article:In practice, we found that one of the important advantages of the in-vial exhaust method is that it can prevent the vaccine from being spilled during exhaust due to technical errors which may be caused by operator inexperience.In addition to the waste caused by spilled vaccine, spillage of vaccine solution causes the “nucleic acid contamination”problem, that is, though the inactivated vaccine has lost its pathogenicity and infectivity, the vaccine-induced nucleic acid testing positive causes unnecessary panic and waste of human and financial resources when dealing with it, which is worthy of attention.In addition, the improvement and innovation of injection methods to save the vaccine and ensure the injection dose are a worthy direction, and we will carry out further research and exploration in the future.We also agree that the relationship of different techniques to syringe dead space is an interesting issue.

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