Dr. Manpreet Bhalla
Md (Microbiology) Senior Microbiologist, Nitrd  National Institute Of Tb & Respiratory Diseases), New Delhi

Q1

JSB: Who all should be tested?

MB:

  1. All asymptomatic individuals who have undertaken international travel in the last 14 days  should be tested only if they become symptomatic (fever, cough, difficulty in breathing)
  2. All symptomatic contacts of laboratory confirmed cases.
  3. All symptomatic health care workers                       
  4. All hospitalized patients with Severe Acute Respiratory Illness (fever AND cough and/or shortness of breath
  5. Asymptomatic direct and high-risk contacts of a confirmed case should be tested once between day 5 and day 14 of coming in his/her contact.

Q2

JSB:  When should specimen be collected

MB: Symptomatic patient who has positive travel history to high risk areas As early as possible after development of symptoms & within 14 days : Asymptomatic direct and high-risk contacts of a confirmed case should be tested once between day 5 and day 14 of coming in his/her contact. Asymptomatic contact of lab tested positive patient- after development of symptoms & within  Day  5 and day 14 of coming in his/her contact.

Q3

JSB: Explain lab diagnosis of COVID 19 Infection

MB: Is done by RT PCR (Real Time Polymerase Chain Reaction ).It is a 2 stage test.

First line screening assay: E gene assay

Confirmatory assay : Orf gene & RdRp gene assay

Right now, First line screening assay is done(on E gene of virus ) & if it is positive, it is confirmed by Confirmatory assay( on Orf gene & RdRp gene of virus ) . Confirmatory test is highly sensitive as it is able to detect just 3.8 RNA Copies/reaction

Additional Confirmatory assay : N gene assay may be done if required

Q4

JSB: What Specimens are collected ?

MB: Mostly  from upper respiratory tract (URT; nasopharyngeal and oropharyngeal) and  sometimes from lower respiratory tract (LRT; expectorated sputum, endotracheal aspirate, or bronchoalveolar lavage) are collected for COVID-19 testing by PCR. COVID-19 virus has been detected in respiratory, fecal and blood specimens. virus can initially be detected in upper respiratory samples 1-2 days prior to symptom onset and persist for 7-12 days in moderate cases and up to 2 weeks in severe cases.

Q5

JSB: Why do we get  FALSE NEGATIVE ?

MB: Specimen collected too early or too late, improper specimen, poor handling or transport of specimen

Q6

JSB: What do you do if you get negative result from a patient with a high index of suspicion?

MB: Repeat collection of sample from lower respiratory tract , if earlier sample was from upper respiratory tract

Q7

JSB: What are other tests for diagnosis?

MB: In addition to above ,PCR positive samples are to be subjected to sequencing protocols for nCoV specific identification in laboratories with Sanger or Next Generation Sequencing.

Serological diagnostics are rapidly being developed but are not yet widely used.

ELISA assays are also under development.

Electron microscopy ( For academic purposes) reveals virus with a characteristic crown morphology:  Coronavirus Cell culture on Vero E6, LLC-MK2 cells and fetal rhesus monkey kidney cells only in WHO recommended reference laboratories.

Q8

JSB: How does COVID-19 spread?

(MB)ANS.8a The disease can spread from person to person through small droplets from the nose or mouth which are spread when a person with COVID-19 coughs or exhales. These droplets land on objects and surfaces around the person. Other people then catch COVID-19 by touching these objects or surfaces, then touching their eyes, nose or mouth. People can also catch COVID-19 if they breathe in droplets from a person with COVID-19 who coughs out or exhales droplets. This is why it is important to stay more than 1 meter (3 feet) away from a person who is sick.

Q8

JSB: Can the virus that causes COVID-19 be transmitted through the air?

MB: Studies to date suggest that the virus that causes COVID-19 is mainly transmitted through contact with respiratory droplets rather than through the air.

Q9

JSB: Can CoVID-19 be caught from a person who has no symptoms?

MB: The main way the disease spreads is through respiratory droplets expelled by someone who is coughing. The risk of catching COVID-19 from someone with no symptoms at all is very low. However, many people with COVID-19 experience only mild symptoms. This is particularly true at the early stages of the disease. It is therefore possible to catch COVID-19 from someone who has, for example, just a mild cough and does not feel ill.

Q10

JSB: What advice you will like to give to community in general ?

MB: Avoiding close contact with people suffering from acute respiratory infections;

  • Frequent hand-washing, especially after direct contact with ill people or their environment;
  • Avoiding unprotected contact with farm or wild animals;
  • People with symptoms of acute respiratory infection should practice cough etiquette (maintain distance, cover coughs and sneeze in elbow or with disposable tissues or clothing, and wash hands.

Interview Taken By 


Dr Jatinder Singh Bhalla 
MS,DNB,MNAMS  
HOD (Ophthal)DDU Hospital,New Delhi
Member Scientific Committee AIOS