To enter The Netherlands, you must be fully vaccinated. Fully vaccinated means a single or double dose has been administered. If your last shot was more than 270 days (9 months) ago, you are required to be administered the booster vaccination. The booster vaccination is valid indefinitely after you receive your booster vaccination. Here is more information regarding the travel restrictions in The Netherlands: https://www.government.nl/topics/coronavirus-covid-19/visiting-the-netherlands-from-abroad/requirements-for-proof-of-vaccination