Mix-and-Match Vaccination Against COVID-19: Review of Latest Evidence .

As COVID-19 vaccine distribution scaled globally, the question of whether mixing vaccine types—such as mRNA and viral vector-based platforms—could offer safe and effective protection became a pressing research focus. Several investigations report strong protection when AstraZeneca is followed by either Pfizer-BioNTech or Moderna. Early US data also indicate that boosting with any of the authorized vaccines produces comparable immune responses and similar reactogenicity, regardless of the primary series received. As countries shift policies in response to safety concerns and supply constraints, the mix-and-match approach continues to gain support as a flexible and reliable option for COVID-19 vaccination.