International travel to Luxembourg is allowed. You need to meet the requirements to ensure entry is allowed.
If another country has been visited in the previous 14 days that is considered high risk, travelers will have to undergo testing and quarantine requirements upon arrival.
Travelers who present a valid international certificate for full vaccination against COVID-19, using an approved vaccine, are exempt from the testing requirements. The final dose must have been administered at least 14 days prior to departure. The vaccine must be authorized by the European Medicines Agency and issued by an EU Member State, a Schengen Area Member State or other specific countries.
Travelers can provide their EU digital certificate on paper or digitally as proof of vaccination, negative test result or prior recovery. Health documents provided in this way will not require additional verification on arrival. Full details on the EU digital certificate, including how EU residents can access their certificate, can be found HERE
Prior to departure, proof of a negative nucleic acid amplification test (NAAT) taken within the preceding 72 hours must be provided. Accepted NAAT tests include PCR, TMA, or LAMP. Alternatively, travelers can present a rapid antigen test, taken within 48 hours. Those who have recently recovered from COVID-19 are exempt from the testing requirements and can provide proof of a positive antigen or PCR test, taken at least 14 days prior to departure and no more than 180 days prior to departure. This only applies to certificates issued by an EU member state or a Schengen member country. The health documentation must be in Luxembourgish, German, French, English, Spanish, Italian or Portuguese.
For more details visit the Luxembourg Government site