Zuellig Pharma, Moderna's supply partner for Covid-19 vaccines in Southeast Asia, said on Tuesday that regional orders for the mRNA vaccine were almost fully booked for this year, highlighting procurement challenges for countries slow off the mark.

Singapore-headquartered Zuellig is involved in the distribution, regulatory approvals and purchase contracts for Moderna Inc's vaccines for use in Southeast Asia, Hong Kong, Macau and Taiwan.

"A lot of the transactions...