The National Command and Operation Centre (NCOC) on Monday allowed booster shots for people over the age of 30 years as Covid-19's latest strain, Omicron, infects 58,000 people in 95 countries. On the other hand, as a large number of people have been denied travel by several countries because of vaccine "discrimination," mix-and-match booster vaccine shots have been permitted free of cost. The term mix-and-match refers to an arrangement under which a person gets a booster shot of a vaccine which.