Обидно было б, если б вышло наоборот.
Сербия не принимает российские сертификаты о вакцинации, см. правила режим для иностранных граждан
https://www.mfa.gov.rs/en/citizens/travel-serbia/covid-19-entry-requirementsCertificate of complete vaccination
issued by the Republic of Serbia, i.e. a foreign state with which the Republic of Serbia has concluded an agreement on the recognition of vaccination (GREECE, HUNGARY, ROMANIA, SLOVENIA*, TURKEY, UNITED ARAB EMIRATES, CZECH REPUBLIC, INDIA) or with which there is de facto reciprocity in the recognition of the vaccination certificate; (ANDORRA, ARMENIA, AUSTRIA, BELGIUM, CABO VERDE, CROATIA, CYPRUS, EGYPT, ESTONIA, FINLAND, FRANCE, GEORGIA, GERMANY, ICELAND, IRELAND, ITALY, LEBANON, LIECHTENSTEIN, LITHUANIA, MALTA, MOROCCO, MOLDOVA, NETHERLANDS, SAN MARINO, SLOVAKIA, SPAIN, SWITZERLAND, TUNISIA, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND, UKRAINE);