The outbreak of a mysterious viral infection in China towards the end of December 2019, took the global medical community by surprise. This was later identified to be severe acute respiratory syndrome coronavirus 2 (SARS-CoV 2), aka COVID 19 virus - a new virus with no established testing or treatment options available

Why is testing for COVID 19 infection important:

In an ideal situation, everyone should be tested for COVID 19 infection. However, given the challenges such as: humongous population, the cost and the logistics of making the equipment and reagents available at testing centres, it is practically impossible to test everyone! Keeping this in mind, Indian Council of Medical Research (ICMR) has recommended to the Government of India (GOI) the following strategy for COVID 19 testing:

• 1. All symptomatic individuals who have undertaken international travel in the last 14 days
• 2. All symptomatic contacts of laboratory confirmed cases
• 3. All symptomatic health care workers
• 4. All 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

In hotspots/cluster (as per MoHFW) and in large migration gatherings/ evacuees centres.

• 6. All symptomatic Influenza like infections (fever, cough, sore throat, runny nose)
• 7. Within 7 days of illness – rRT-PCR
• 8. After 7 days of illness – Antibody test (If negative, confirmed by rRT-PCR)

Asper ICMR note, till 14th April 2020, a total of 2,44,893 samples from 2,29,426 individuals have been tested and 10,307 individuals have been confirmed positive among suspected cases and contacts of known positive cases in India.

What are the tests for COVID 19 ?

Soon after Wuhan was ravaged by this mysterious viral illness, a team led by Yong-Zhen Zhang, of the Shanghai Public Health Clinical Centre & School of Public Health, did a commendable job of mapping the COVID 19 viral genetic structure. This enabled the scientists to identify COVID 19 genetic footprints and develop specific kits to be used through Reverse transcription polymerase chain reaction(RT-PCR). Incidentally, there are multiple RT PCR based tests, which are recommended by Centers for Disease Control and Prevention (CDC) and WHO as the initial test for screening COVID 193. Other option is to conduct serological tests to look for specific antibodies produced by the body in response to COVID 19 viral antigens and identify the infected persons.

• Real time reverse transcription polymerase chain reaction (rRT-PCR) : Can be done on samples obtained by various methods, including a throat swab or sputum sample. Targeted viral genes include N, E, S and RdRp gene. Results are generally available within a few hours to 2 days. This test confirms recent or active infections.
• Serological tests: Tests done using blood samples for diagnosis and population surveillance. A positive test indicates that individual had COVID 19 infection as evidenced by antibodies including IgG and IgM (Antibodies are detectable 14 days after the infection). The serological tests can be done in a central laboratory or by point of care systems

Indigenously developed tests for COVID 19 testing:

While there are plenty of tests developed for COVID 19 testing from other countries, it is noteworthy that some of the Indian companies have developed tests which have been approved by CDSCO.

• Pune based Mylab Discovery, became the first Indian company to get Central Drugs Standard Control Organisation (CDSCO) approval for COVID 19 test. The rRT-PCR test is priced at Rs 1200 and result is given out within 2.5 hours. Besides this, Truenat Beta PCR from Molbio Diag. Pvt Ltd Goa, TruPCR from Kilpest India Ltd, Bhopal, PCR from Medsource Ozone Biomedicals Pvt.Ltd have also recently received the CDSCO approval.
• Voxtur Bio Ltd, Vanguard Diag Pvt Ltd and HLL have developed serological testing methods which are approved by the CDSCO. These tests establish diagnosis by testing for specific antibodies.

References:

• Revised Strategy for COVID19 testing in India (Version 4, dated 09/04/2020). At URL: https://icmr.nic.in/sites/default/files/upload_documents/Strategey_for_COVID19_Test_v4_09042020.pdf. Accessed on 25/04/2020
• SARS-CoV-2 (COVID-19) Testing: Status Update 14 April 2020 9:00 PM IST, ICMR India. 14 April 2020. At URL https://icmr.nic.in/sites/default/files/whats_new/ICMR_testing_update_14April_9PM_IST.pdf. Accessed on 15/04/2020
• CDC Tests for COVID-19, From CDC website at URL https://www.cdc.gov/coronavirus/2019-ncov/php/testing.html. Accessed on 15/04/2020
• Advice on the use of point-of-care immunodiagnostic tests for COVID-19. WHO at URL https://www.who.int/news-room/commentaries/detail/advice-on-the-use-of-point-of-care-immunodiagnostic-tests-for-covid-19, accessed on 15/04/2020
• Extracted from Public notices from CDSCO website, available at https://cdsco.gov.in/opencms/opencms/en/Notifications/Public-Notices/, accessed on 15/04/2020