COVISHIELD: Gap between doses increased

The Government of India recently increased the gap between the two doses of the COVISHIELD Vaccine. The gap was increased from six to eight weeks to twelve to sixteen weeks. This is the second time in three months, the gaps between the doses of COVISHIELD have been widened. In March 2021, the Union Territories and State Governments were asked to increase the gap from twenty-eight days to six to eight weeks.

Why was the gap increased?

The COVID-19 Working Group recommended to increase the gap based on the real-life evidences from the UK. The recommendations were agreed by NEGVAC (National Expert Group on Vaccine Administration). Currently, the gap between the doses are four to six weeks.

The protection against the vaccines increased if the gap between the doses are increased. In Canada the gap between the doses are three to four months.

A Lancet study says that the protection (efficacy) against COVID-19 increased from 55.1% to 81.3% if the gap between the doses was increased from six to eight weeks to twelve to sixteen weeks.

Why two doses?

The immunity to COVID-19 plateaued after the first dose. Thus, the second dose is essential to boost the immunity to higher levels. The COVID-19 recovered people should get booster dose after six months.

The time gap between doses of COVAXIN has not been altered. This is because COVAXIN was completely developed in a different way. It is an inactivated vaccine that contains dead COVID-19 virus. It teaches the immune system how to defend the body against the virus. On the other hand, the COVISHIELD was developed using a vector called Adeno virus.

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