COVID-19 vaccination in India: Here is why second dose of Covishield will be given after an interval of 6-8 weeks

Coronavirus vaccination: Many studies have shown that when the vaccine is administered with a gap of 6-8 weeks between the two doses, the protection is enhanced. In a meeting, the National Technical Advisory Group on Immunization (NTAGI) and National Expert Group on Vaccine Administration for COVID-19 (NEGVAC) have agreed to increase the gap between the two doses on the back of scientific evidence. After recommendations were made, the Union Health Ministry has also agreed to it. However, this is only applicable for Oxford-AstraZeneca’s Covishield and not Bharat Biotech-ICMR’s Covaxin.

Now, as per the recommendations, the second dose which earlier used to be administered at 4-6 weeks can be stretched till 6-8 weeks. Union Health Secretary Rajesh Bhushan in a written letter informed the Chief Secretaries of States/UTs regarding centre’s go-ahead for increasing the interval between two doses of the COVID-19 vaccine. The ministry said “it has accepted the recommendations made by NEGVAC and NTAGI.” It added that as per the new guidelines, states and UTs can administer the second dose of Covishield to beneficiaries within the 4-8 weeks after the first dose is given.

It is to note that the existing scientific evidence has indicated improved protection given that the interval between vaccine administration increases. As per the Oxford University and AstraZeneca, the interim results from phase 3 clinical trials showed that when the administration interval between two doses of vaccine was four weeks, 79 per cent efficacy was noted against symptomatic patients. In some critical and severe cases, this efficacy was found to be 100 per cent. These trials were conducted among 32,000 participants across the US, Peru and Chile. The efficacy was found to be higher in the UK and Brazil.

It is important that this stipulated period of 8 weeks should not be exceeded. Citing Dr N K Arora of NTAGI, a report by The IE noted that the administration of the second dose should not be increased beyond 8 weeks, especially in India where there is no shortage of vaccines. For countries not having sufficient vaccines an increase can be recommended but India has no such problem. Moreover, an increased stipulated period beyond 8 weeks will also result in a higher chance of getting an (COVID-19) infection between the two doses, Arora asserted.

The health ministry has also urged all the States and UTs to take all steps necessary so that the instructions regarding revised vaccine administration duration are passed on to vaccinators, programme managers as well as the recipients of Covishield vaccine.

These instructions have come at a time when around 45 million people in India have been given vaccine shots (at least first dose). India is in the second phase of its vaccination drive where the aim is to vaccinate people above 60 years of age and those above 45 years with comorbidities. In the first phase, healthcare workers and frontline workers were given the vaccine. The IE report also pointed out that delay in the second dose will also result in more vaccination of people in the priority group as more doses are free for inoculation.