Corporate mergers and competition from supermarkets, discount clubs and online startups — among other forces — have altered how pharmacies need to do business.

CVS has found a positive side effect of providing vaccines — increased retail sales. But what happens when vaccinations slow down?

Pharmacies like CVS and Walgreens have to consider storage requirements, more staffing and store layout for vaccine distribution.

Many of the companies already work with those facilities to supply drugs and provide flu shots for residents.