A journey of COVID protection to vaccination

As we complete the anniversary of the discovery of Covid-19 and its microbe, the tiny RNA SARS CoV2 virus, the global spotlight in December will be how to offer protection from Covid-19. Essentially, nothing can replace aggressive face covering (masking) with distancing (physical) with sanitisation, apart from avoiding crowded clusters and poorly ventilated spaces. Independent of Covid appropriate behaviour, the big question is does exposure to SARS Cov2 confer some degree of protection from Covid-9 reinfections? It's still elusive that anti-Covid antibodies don’t mean protection but exposure; we don’t know how long antibodies will stay or decline, nor do we know if our body T-cells memorise the virus when it was exposed. Covid virus equations are still in infancy and we only know its predictably unpredictable Herd Immunity attempts.

The vaccine has been the biggest ray of hope currently and rapid strides have been made to develop a vaccine which is safe and effective. Most vaccines use the protein sequences of the SARS Cov2 virus which cover the virus or its crown and generate an immune response. Usually, these protein-based vaccines don’t need very cold storage called “Cold Chain”. Other vaccines are from nucleic acid-like RNA or DNA. Usually, the mRNA vaccines made by Pfizer or Moderna need storage at -70 °C, which is a logistical nightmare. These vaccines are essentially researched in the USA, UK and Europe. They are likely to get Emergency Use authorisation by the FDA but are unlikely to be available for India in 2021. They offer 94 to 95 % protection but side effects are yet not fully known.

In India, we have two made in India vaccines. First is the Bharat Biotech ICMR vaccine “Covaxin” which is not in Phase 3 after completing Phase 1 and 2 trials. It is an inactivated virus vaccine (the virus is killed by a reagent). To boost the antigenicity an additional substance (adjuvant) is added but we don’t know its efficacy though is likely to be safer. The virus used is from Indian ICMR National Institute of Virology, Pune and is an Indian strain. The phase 3 trials are being conducted across India including Mumbai, Delhi and if it shows promise in interim data it may apply for emergency use with the regulator. It's phase 1 and 2 trial data has been approved and studied by the expert committee of the Drug controller of India who has allowed it now to proceed with the final phase pre-approval.

The second Indian vaccine is made by Zydus which is a DNA vaccine. This DNA based vaccine is delivered via the skin by a special mechanism and maybe India's answer to Pfizer or Moderna mRNA vaccine. It's easy to manufacture and store and can change the genetic mutations like the flu vaccine. It has completed Phase 1 and 2 trials and is about to start Phase 3 trials. It has been safe and final data is anticipated.

(The author is an endocrinologist, Dean, Indian College of Physicians, and a member of the state COVID-19 task force and the state’s vaccination task force)

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