To verify that you are a human and not a bot, we use a simple but effective method. When you press and hold the “I’m not a robot” button on our website, a reference ID is generated. This unique code is sent to your device for verification purposes.
The reference ID is linked to your account activity and can be used by our system administrators to verify that you are indeed a human user. By using this technology, we ensure that our website remains safe from automated traffic and spam bots.
To confirm, simply press the “I’m not a robot” button again, or enter the generated reference ID in the designated field. If everything is correct, you will be granted access to our site.
Source: https://www.sfchronicle.com/health/article/covid-cases-rise-california-20770101.php