The European Union has proposed a nine-month ‘expiration date’ on COVID-19 vaccination passports for visitors, meaning travelers will have to get a booster shot to extend the validity of their certificate.

The EU made the proposal to help stem the tide of a surge in coronavirus cases across Europe that has resulted in several countries, including Austria, to go into a lockdown.

Known as the EU Digital COVID Certificate, the pass is valid for travel across Europe for nine months following the second dose.

Members of the EU have the option to accept or decline the recommendation, although according to documents seen by Bloomberg News Service the EU did say that countries should continue to prioritize and welcome fully vaccinated visitors.

The proposal is not as much controversial as it is problematic. The European Centre for Disease Prevention and Control (ECDC) noted that the vaccine tends to lose its efficacy after six months, hence needing the booster shot. Whether some people will want, or need, the booster after getting the original vaccine remains to be seen.

Travelers who do get the booster will be able to add it to their National Health Service COVID Pass for quick and easy identification.

United Kingdom Health Secretary Sajid Javid told The Telegraph newspaper in London that “We want to make it as easy as possible for people to show their vaccine status if they are travelling abroad. This update to the NHS Covid Pass will mean people can have their complete medical picture at their fingertips if they are going on holiday or seeing loved ones overseas. Getting a top-up jab (booster) is our best defense against this virus and I urge all those who are eligible to come forward and get boosted.”