Understand the confusion and hesitancy. There are scientific studies out there that do indicate that it is safe and may actually provide a stronger immune response. Especially when mixing Astrazeneca with one of the mRNA vaccines. Agree there are no long term studies on the effects of mixing the vaccines, but so true is the fact that there are no long term studies on the effect of COVID itself. So, from all the data so far it seems safe. I myself had Aztrazeneca and Moderna (and had a pretty strong response.) So, the science is there to help steer informed decisions.

Here are a few links:

• Safety and Immunogenicity Report from the Com-COV Study – a Single-Blind Randomised Non-Inferiority Trial Comparing Heterologous And Homologous Prime-Boost Schedules with An Adenoviral Vectored and mRNA COVID-19 Vaccine
  https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3874014
• Heterologous prime-boost COVID-19 vaccination: initial reactogenicity data
  https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01115-6/fulltext
• Reactogenicity and Immunogenicity of BNT162b2 in Subjects Having Received a First Dose of ChAdOx1s: Initial Results of a Randomised, Adaptive, Phase 2 Trial (CombiVacS)
  https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3854768