Entry into Serbia will be allowed only with a negative PCR test, not older than 48 hours. Citizens of the Republic of Serbia, who do not have a negative PCR test, must be in home isolation for 10 days. They can be tested in Serbia and if their PCR test is negative, they will no longer be required to be in home isolation.
The following categories of citizens are exempted from the afore-mentioned conditions when entering the Republic of Serbia:
1. foreign citizens transiting through the territory of the Republic of Serbia. Transit for foreign citizens shall be limited to the period of up to 12 hours from the time of entry to the territory of the Republic of Serbia;
2. flight crew and cabin crew on aircraft with the Republic of Serbia as end destination, or transiting via international airports in the Republic of Serbia;
3. Accredited members of foreign diplomatic/consular missions and offices of international organization as well as members of their families, holders of special identity cards i.e. ID documents issued by the Ministry of Foreign Affairs and the General Secretariat of the Government;
4. children of up to 12 years of age, if the parent, legal guardian or a person from the family household who is accompanying the child has a negative PCR test not older than 48 hours;
5. foreign citizens with a leave to stay or permanently settle in the Republic of Serbia;
6. citizens of neighbouring countries living in small-border areas who are employed in the territory of the Republic of Serbia, to whom the employer issued a document as a proof of work engagement, on the condition of reciprocity.
7. foreign citizens carrying out international transport activities, retrieving or unloading goods, or for the purpose of transport of persons to or through the Republic of Serbia, applicable to the crews of:
- freight motor vehicles in international road traffic. In case of transit, the same shall be limited to the period of up to 12 hours from the time of entry to the territory of the Republic of Serbia;
- cargo ships transporting goods to one of the domestic ports. In case of transit sails along the international waterway in the territory of the Republic of Serbia, the same shall be limited to a period of up to 90 hours for ship compositions and 60 hours for self-propelled vessels from the time of entry into the territory of the Republic of Serbia for upstream navigation, or limited to a period of up to 72 hours for ship compositions and 54 hours for self-propelled vessels from the time of entry into the territory of the Republic of Serbia for downstream navigation;
- shuttle buses and buses carrying out international transport of passengers, both in case of transits and when the Republic of Serbia is both their final and departure destination;
- railway vehicles and train crews;
- humanitarian convoys arranged through diplomatic channels.
Please bear in mind that there are nationwide rules in place restricting movement and limiting activity. It is mandatory to maintain physical distance of at least 1.5m in all public spaces. Protective face masks are mandatory in all public indoor spaces as well as in outdoor spaces where is not possible to maintain distance. You should follow the latest local guidance - check news outlets regularly for up to date information.
Questions and answers on entry and stay in Switzerland please find here

https://www.sem.admin.ch/sem/en/home/aktuell/aktuell/faq-einreiseverweigerung.html#2140317167

or contact the Embassy of Switzerland in Belgrade

https://www.eda.admin.ch/countries/serbia/sr/home/vertretungen/botschaft.html