North Korea has rejected planned shipments of AstraZeneca's COVID-19 vaccine that were being organized under the global COVAX distribution plan due to concerns over side effects, a South Korean think tank said Friday.

COVAX has said it would provide nearly 2 million doses of AstraZeneca's shots to North Korea. The first batch had been expected in late May but was delayed amid protracted consultations, South Korea said last month.

North Korea has not reported any COVID-19 cases, a position questioned by South Korean and U.S. officials. The reclusive country has, however, imposed strict anti-virus measures, including border closures and domestic travel curbs.