The gap between the first and second doses of the Covishield COVID-19 vaccine has been increased to 12-16 weeks - from the existing six-eight weeks - the government said recently. No changes have been announced in dosage intervals for Covaxin, which remains at four to six weeks. NDTV's Rishika Baruah explains this change and why has it been done. Also know more about coronavirus variants found in India and if the current vaccines are effective against these.