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J Med Virol
. 2021 Jul 14.
doi: 10.1002/jmv.27204. Online ahead of print.
Effect of Different Storage Conditions on Covid-19 RT-PCR Results
Elif Yilmaz Gulec 1 2 , Nevra Pelin Cesur 3 4 , Gonca Yeşilyurt Fazlioğlu 3 5 , Cemal Kazezoğlu 2 6
Affiliations
- PMID: 34260086
- DOI: 10.1002/jmv.27204
Abstract
Reliable and rapid detection of SARS-CoV-2 in laboratory setting is critical to control the pandemic. We aimed to evaluated PCR efficiency of nasopharyngeal swabs stored in viral transport medium (VTM) in different temperatures. Ninety swabs taken into VTM were analyzed at first hour, then divided into 2 groups with similar numbers of positive and negative samples. Positive samples of each group were also sub-grouped according to Fam CT values as low CT (<25), medium CT (25-32) and high CT (32-38) groups. One group was stored at 4º C, while the other was stored at room temperature, PCR analyses were repeated every 24 hours for 5 days and on day 12. There was a total of 30 positive samples (12 low CT, 11 medium CT, 7 high CT). The CT values of both groups remained unchanged in first 3 days while the CT values of room temperature group increased after 3rd day. All of the positive samples remained positive in both groups for first 5 days. On the 12th day the total number of positives decreased to 8 in the room temperature group and 11 in the 4º C group. All the low CT samples remained positive in both groups. In conclusion it is safe to store positive samples in room temperature for up to 5 days. Only samples with high viral loads remain positive for 12 days, regardless of whether stored at room temperature or 4ºC. Negative samples don't turn to invalid if stored in VTM. This article is protected by copyright. All rights reserved.
Keywords: Coronavirus; Covid-19; Polymerase Chain Reaction; RT-PCR; SARS-CoV-2; Viral Transport Medium.