Replication of SARS-CoV-2 in cell lines used in public health surveillance programmes with special emphasis on biosafety

Background & objectives: Polio, measles, rubella, influenza and rotavirus surveillance programmes are of great public health importance globally. Virus isolation using cell culture is an integral part of such programmes. Possibility of unintended isolation of SARS-CoV-2 from clinical specimens processed in biosafety level-2 (BSL-2) laboratories during the above-mentioned surveillance programmes, cannot be ruled out. The present study was conducted to assess the susceptibility of different cell lines to SARS- CoV-2 used in these programmes. Methods: Replication of SARS-CoV-2 was studied in RD and L20B, Vero/hSLAM, MA-104 and Madin–Darby Canine Kidney (MDCK) cell lines, used for the isolation of polio, measles, rubella, rotavirus and influenza viruses, respectively. SARS-CoV-2 at 0.01 multiplicity of infection was inoculated and the viral growth was assessed by observation of cytopathic effects followed by real-time reverse transcription–polymerase chain reaction (qRT-PCR). Vero CCL-81 cell line was used as a positive control. Results: SARS-CoV-2 replicated in Vero/hSLAM, and MA-104 cells, whereas it did not replicate in L20B, RD and MDCK cells. Vero/hSLAM, and Vero CCL-81 showed rounding, degeneration and detachment of cells; MA-104 cells also showed syncytia formation. In qRT-PCR, Vero/hSLAM and MA-104 showed 106 and Vero CCL-81 showed 107 viral RNA copies per ?l. The 50 per cent tissue culture infectious dose titres of Vero/hSLAM, MA-104 and Vero CCL-81 were 105.54, 105.29 and 106.45/ml, respectively. Interpretation & conclusions: Replication of SARS-CoV-2 in Vero/hSLAM and MA-104 underscores the possibility of its unintended isolation during surveillance procedures aiming to isolate measles, rubella and rotavirus. This could result in accidental exposure to high titres of SARS-CoV-2, which can result in laboratory acquired infections and community risk, highlighting the need for revisiting biosafety measures in public health laboratories

Clinical Profile of Critical Pertussis in Children at a Pediatric Intensive Care Unit in Northern India

Objective: To delineate the clinical profile, complications, intensive care needs, andpredictors of mortality in children with critical pertussis. Methods: Retrospective analysis ofcase records of children in the pediatric intensive care unit of a tertiary-care hospital, with adiagnosis of critical pertussis over 3 years. Diagnostic criteria included CDC case definitionand confirmation by polymerase chain reaction (PCR), when available. Survivors and non-survivors were compared to identify predictors of mortality. Results: 36 records wereanalysed, most cases were infants (31, 86.1%). 10 (27.7%) were (below 6 weeks of age). Inthe rest, 16 (61.5%) were partially immunized or unimmunized against pertussis. Rapidbreathing (88.9%), paroxysmal cough (86.1%) and apnea (41.7%) were common presentingcomplaints. Hypoxemia (97.2%), hyperleukocytosis (61.1%) and encephalopathy (52.8%)were common complications. Intensive care needs were mechanical ventilation in 11(30.6%), vasoactive support in 7 (19.4%) and exchange transfusion in 3 (8.3%). Femalegender, apnea, hyperleukocytosis, encephalopathy, need for vasoactive support, andmechanical ventilation predicted mortality. Conclusion: Pertussis demands attention due toits varied presentation, increased complications and higher mortality.