Pharmaceutical company AstraZeneca announced Wednesday morning that its COVID-19 vaccine trial is on hold after a volunteer in the UK had an unexplained illness.

The trial is for a vaccine in development by pharmaceutical company AstraZeneca and Oxford University. It's one of three vaccines in the U.S. in the final stage of study before Food and Drug Administration approval for widespread use.

Some parents are opting out of getting their children vaccinated, and last year that led to the worst measles outbreak the U.S. has seen in more than two decades.

Indianapolis Animal Care Services has seen over 50 parvo cases at animal intake in the last week.

IndyCar medical director Geoffrey Billows said Thursday a "very limited supply" of vaccines will be available at the medical building.

The district will partner with companies CareDox and Healthy Schools to provide free flu shots and vaccines.

Public health experts are noting the differences in vaccination requirements at Indiana colleges in the wake of three schools announcing cases of the mumps this year.