NAGPUR: With fewer detection of Omicron variant among severely ill patients, doctors have warned that the Delta variant could still be in circulation. Samples of only a few in ICUs are testing positive in Omisure RT-PCR kits, which are said to guarantee detection of all Omicron lineages in RT-PCR tests. These were deployed after Omicron lineages, especially the BA.2 variant, skipped ‘S’ gene target failure (SGTF) RT-PCR run.
The district and civic authorities had procured SGTF kits on a large scale for Omicron surveillance in December-January. However, the strategy had to be tweaked after some samples showed BA.2 lineage and the administration procured Omisure kits.
Samples of moderate to severely ill patients from medical colleges and private Covid hospitals are being subjected to Omisure RT-PCR testing. However, in these tests too not all samples are testing positive for Omicron lineages, raising a question about the variant.
Though the number of samples is around 30, only five of them have tested positive for Omisure RT-PCR indicating Omicron variant. The negative samples have been sent to NIV Pune to ascertain the variant.
IGGMCH officials said they have stopped SGTF RT-PCR tests and are now sending samples of hospitalised patients to NIV Pune for genome sequencing to ascertain the variant. IGGMCH’s Viral Research and Diagnostics Lab (VRDL) is sentinel centre for Covid surveillance. Around 30 samples from the centre are under study at NIV Pune.
Dr Meena Mishra, professor and head, department of microbiology, AIIMS Nagpur, said they have started using Omisure RT-PCR kits on samples of hospitalized Covid positive patients. “Only a few were found to be carrying the Omicron variant. The others have been sent to NIV for genomic sequencing. There is a strong possibility that though it is being widely assumed that Omicron and sub-variants are now dominant, Delta has still not gone away completely.”
“Earlier, we used the SGTF RTPCR kits and only those sample with ‘S’ gene drop were sent for sequencing. Rest of the samples were never studied while different studies indicated surge of Omicron. Hence, we need to still focus on Delta, as some people are getting moderate to severe manifestations due to Covid. The study of samples taken from serious patients will reveal which variant they are affected with,” she said.
So far, the district has reported 135 deaths in the ongoing third wave. Over 500 Covid patients are still admitted.
