I'm going to say this: The way governments have communicated information about things has been...well...poor. When the virus first came, officials said people shouldn't mask up. The main reason: they were concerned about not having enough PPE for medical professionals dealing with the first wave of patients. Then it was wear a mask, but a lot of people now are wondering why they flipped on it - leading to some distrust.
So, with this new mixing vaccines - I honestly don't blame people for being sceptical. But, they have studied it, and it does look like it is more effective for people who got their first dose as AZ and either Pfizer or Moderna for the second. I think if you got Pfizer then Moderna, it probably didn't make a huge difference.
Anyways, I am confident that getting two doses will help prevent the spread. The challenge is getting enough people to get both shots. There are so many people hesitant about getting it. And our world will really not return to normal until enough people get vaccinated. It's just a fact. It'll either be that, or we're going to lose a bunch of the anti-vaxx crowd. And some vaccinated people as well. Remember, no vaccine is 100% perfect. There is always a chance a vaccinated person can get the disease, but the odds are slim. And usually, when if they get it, the symptoms are less severe than an unvaccinated person.