The United States has upgraded its travel warnings for Britain, Indonesia and three other destinations, advising Americans not to travel there due to a surge in coronavirus cases.

The CDC and the State Department issued revised advice to U.S. travelers Monday alerting them to the increased risk of contracting COVID-19 in Britain, Indonesia, Zimbabwe, Fiji and the British Virgin Islands. Previously, all had been covered by a less severe advisory to “reconsider travel.”

The advisories are recommendations that are constantly under review and are not binding, although they may affect group tours and insurance rates.

The warning for Britain, for example, has fluctuated between Level 3, or “reconsider travel,” and Level 4, or “do not travel,” several times this year already.

“If you must travel to the United Kingdom, make sure you are fully vaccinated before travel,” the CDC says in the alert.