Study

Viral Transmission Risk Found in NAT Experience Study

AIIMS conducted the first evaluation in an Indian Government setting to find necessity and feasibility of NAT testing in an individual donor format

Further to a diktat from the Supreme Court, the Indian Government made blood screening mandatory in 2000, given the high prevalence of hepatitis and HIV in India. However, existing standard of care (ELISA serology testing) in India continues to allow a 'window period' between viral infection and viral detection. Unlike countries where compulsory NAT has ensured the safest blood supply possible, Nucleic Acid Testing (NAT) is still not mandatory in India. Keeping this in mind, AIIMS decided to undertake the 'AIIMS NAT Experience' study to identify the risk of HIV and Hepatitis transmission from blood transfusions in an India Government setting, and like other countries in Asia Pacific the ability of NAT to intercept and prevent this risk.

NAT is a molecular technique used to directly detect the virus genetic materials. It utilises nucleic acid probe target amplification technology for the detection of HIV-1, HCV and HBV DNA. It is a test that helps shorten the window period — the period from when a patient has been infected to when they show up as infected by testing positive to existing serology tests.

The pilot study, conducted on 5,818 donor samples for the presence of HIV, Hepatitis B and C, detected the presence of five NAT positive and sero-negative cases. This equates to a risk of 1:1,164 for a missed sample, and is consistent with other studies conducted in Asia Pacific (China and Taiwan) and Africa (South Africa) where there are high prevalence of the viruses.

Said Dr Kabita Chatterjee, Faculty in-charge, Blood Bank at AIIMS, New Delhi and Principal Coordinator of the study, "We compared NAT tests with the standard testing methods in use and found that with the current testing methods it is difficult to identify the viruses during the 'window period', where the virus is still multiplying in the body but the donor may unknowingly donate infected blood. Moreover, each bag of donated blood collected can be transfused in up to three patients. With 7.4 million blood donations collected annually in India, that equates to more than 6,000 donations potentially missed with existing testing technologies, and up to 20,000 patients and families being adversely affected."

Dr Kabita further added, "A new molecular technology based on the principle of Transcription Mediated Amplification (TMA) enables magnification of even very low amounts of viral genetic material, and allows for individual donation testing (IDT) to maximise test sensitivity. Given the frequent presence of low viral concentrations in many blood donation samples and the high viral prevalence in the Indian setting, TMA in IDT format is ideal to ensure maximum possibility of viral interception."

The study also confirms the feasibility of NAT testing in India, both in the Government and private setting. As a matter of fact, NAT is already available in India. Said Dr Anand Deshpande, Consultant, Transfusion Medicine, PD Hinduja Hospital, Mumbai, "NAT is part of the routine testing in 12 blood centres across India such as AIIMS, Hinduja Hospital, RML Hospital, Apollo Hospital and others. Implementation of NAT is an important step forward in the prevention of transfusion transmission infections in India. In fact, the Government and various blood banks have already planned adoption and implementation of NAT to increase the availability of a safer blood supply."

Said Dr Kanjaksha Ghosh, Director, Institute of Immunohaematology, Mumbai, "The 'NAT Experience' study has highlighted the need for a patient centric approach to blood safety by making tests like NAT mandatory in India and to ensure we have the safest possible blood supply in India."

EH News Bureau