According to official information from the Ministry of Health of Bahrain, from January 9, all passengers aged six years and older arriving in the Kingdom of Bahrain are subject to the following "anti-COVID measures":

Fully vaccinated passengers and passengers who have recently recovered from COVID-19 infection must present a PCR test negative 72 hours prior to boarding a flight to Bahrain, and must undergo a PCR test upon arrival in Bahrain.
Unvaccinated tourists will still need a 10-day quarantine at the hotel, as well as similar two PCR tests.
Note that previously three tests were required to enter the country: not only upon arrival, but also on the fifth and tenth days of stay. Moreover, the tests were and remain paid. The cost of one is 12 Bahraini dinars.