A container with boxes of the Pfizer vaccine delivered, at the Sarajevo Airport, Bosnia, Tuesday, May 4, 2021. The European Union has started delivering EU-funded coronavirus vaccines across the Balkans, where China and Russia have for months been supplying the much-needed shots and thus making political gains. (AP Photo/Eldar Emric)

Austria's Foreign Minister Alexander Schallenberg speaks at Sarajevo Airport, Bosnia, Tuesday, May 4, 2021. The European Union has started delivering EU-funded coronavirus vaccines across the Balkans, where China and Russia have for months been supplying the much-needed shots and thus making political gains. (AP Photo/Eldar Emric)

A container with boxes of the Pfizer vaccine delivered, at Sarajevo Airport, Bosnia, Tuesday, May 4, 2021. The European Union has started delivering EU-funded coronavirus vaccines across the Balkans, where China and Russia have for months been supplying the much-needed shots and thus making political gains. (AP Photo/Eldar Emric)

A container with boxes of the Pfizer vaccine delivered, at the Sarajevo Airport, Bosnia, Tuesday, May 4, 2021. The European Union has started delivering EU-funded coronavirus vaccines across the Balkans, where China and Russia have for months been supplying the much-needed shots and thus making political gains. (AP Photo/Eldar Emric)

A medical worker gives a shot of Chinese Sinopharm COVID-19 vaccine to a woman during the vaccination in Podgorica, Montenegro, Tuesday, May 4, 2021. The European Union started delivering EU-funded coronavirus vaccines Tuesday to the Balkans, a region that wants to join the 27-nation bloc but where China and Russia have already been supplying the much-needed shots and making political gains. (AP Photo/Risto Bozovic)

EU enlargement commissioner Oliver Varhelyi speaks during a press conference in Podgorica, Montenegro, Tuesday, May 4, 2021. The European Union started delivering EU-funded coronavirus vaccines Tuesday to the Balkans, a region that wants to join the 27-nation bloc but where China and Russia have already been supplying the much-needed shots and making political gains. (AP Photo/Risto Bozovic)

EU enlargement commissioner Oliver Varhelyi speaks at the Sarajevo Airport, Bosnia, Tuesday, May 4, 2021. The European Union has started delivering EU-funded coronavirus vaccines across the Balkans, where China and Russia have for months been supplying the much-needed shots and thus making political gains. (AP Photo/Eldar Emric)