The government has a program for it which they are the ones going to buy the vaccines. No one, no company is allowed but the government alone can buy these vaccines and this is for the purpose of transparency. The program includes "Bayanihan" Basically its about helping each other.
A big company contributes to buying some vaccines has to give back while the government had allowed them for this procurement.
There is no blackmailing there, these companies sign contracts and agreed to help each other before they buy these vaccines.
The employees receive vaccines and at the same time the government get some vaccines to provide for the people, in fact former Senator BAM AQUINO was vaccinated.