The chaos at Kabul Airport is also causing a delay in the delivery of medical supplies.
He singled out vaccine makers Pfizer and Moderna as companies that were aiming to provide booster shots in countries where there were already high levels of vaccination.
The United States is likely to distribute 200 million shots this year and 300 million in the first half of next year.
Iran and Turkey rank 6th and 9th respectively for most new cases of the coronavirus worldwide
Blinken in Ramallah: US to secure 1.5 million COVID vaccines for Palestinians
"The severity of injuries is straining an already overwhelmed health system that is facing critical shortages of essential medicines and supplies while also battling the COVID-19 pandemic."
Moderna announced this week an expansion plan for its production network to boost its capacity to up to 3 billion doses in 2022.
So far COVID-19 vaccines made by Pfizer, AstraZeneca and Johnson & Johnson have received WHO approval, which is a signal to national regulatory authorities on a product's safety and efficacy.
Two batches, in additional to the already procured 54,000 doses, are expected to arrive throughout the year to cover around 850,000 people in northwest Syria.