California on Friday started offering citizens an electronic record of their coronavirus vaccinations they can use to access businesses or events which require evidence they got the shots.

The state’s public health and technology departments said the new tool allows Californians access for their own COVID-19 vaccination records from the state’s immunization registry and contains the Exact Same data as the paper cards issued from the Centers for Disease Control and Prevention

The record will have a QR code that users can save to their mobile phones.

With almost 20 million people fully vaccinated in California and proof of vaccination already needed in some circumstances such as traveling, country health officials believed there could be demand for the instrument, though it remains optional, said Dr. Erica Pan, the state’s epidemiologist.

“The odds are someone is going to misplace their paper CDC card along with a digital COVID-19 vaccine record provides a handy backup,” she told reporters.

After a drop in COVID-19 infections and rise in vaccinations, California lifted many pandemic-related constraints this week, even though everybody has to continue to use masks in certain places such as mass transit and health facilities.

Vaccinated individuals are no longer needed to wear masks most indoor places, though the unvaccinated still have to do so. Businesses can select whether to operate on an honor system for those who must wear face coverings, need everyone to use them or use a vaccine verification system.

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Vaccine verification has been a thorny issue in many U.S. communities. About two dozen states have banned state-required vaccine passports and some, including Texas, also barred businesses from requiring vaccinations.

New York offers electronic vaccine verification through a digital app called Excelsior Pass.

California is giving residents quick access to their individual records in a database the state already maintains on immunizations, which residents could already get by making a request, said Amy Tong, director of the state’s department of technology.