AUSTIN, Texas — It's a day most Texans have been waiting for. Beginning Monday, Texas will be the largest state to make COVID-19 vaccines available to adults 16 and older. 

The drastic expansion for the state comes as state health officials say they expect supplies to increase next week. But demand for the vaccine still far outweighs supply as the announcement makes about 22 million people eligible. 

"There is increasing supply coming. We have three vaccines now," Dr. Mark McClellan, a former FDA Commissioner and medical adviser to Gov. Greg Abbott, said. "It doesn't mean that next week everybody is going to be able to go out and get a vaccine. But the supply is increasing and I think it is time for everybody to be thinking about, are they getting their questions answered? Are they ready to get a shot when they get their turn and sign up, get in line?" 

So far, Texas has administered more than 9 million doses of the vaccine. More than 6 million have gotten at least one dose and over 3 million people are fully vaccinated. Health experts say between 70% and 90% of Texans must be vaccinated in order to reach herd immunity and stop the spread of the virus. 

Dr. McClellan says now is not the time to let your guard down because it's going to take awhile to get to that point. 

"I hope we can keep taking it step by step, not turn off all the precautions now, in order to get those cases down and really move beyond this pandemic," he said. "If we do this right, a lot can happen over the next couple of months and I think the summer looks pretty good."  

Next week, state health officials will launch a website to allow people to register for the shot through some public health providers. You can also find additional providers by going to the DSHS website. A toll-free number will also be available soon for people who need help signing up. 

State health officials are still asking providers to prioritize people who are 80 and older.