COVID-19 vaccines can use different technologies. Pfizer-BioNTech and Moderna vaccines use messenger RNA (mRNA); Novavax uses a protein-subunit approach. These are different ways to present a target to the immune system, not a simple ranking of “better” and “worse.”
How the platforms differ
An mRNA vaccine provides temporary instructions that help cells make a target protein so the immune system can learn to recognize it. The mRNA is broken down by the body. A protein-subunit vaccine supplies a selected protein component with an adjuvant to help prompt an immune response. Neither approach uses a live SARS-CoV-2 virus to cause COVID-19.
What effectiveness figures mean
Protection depends on the vaccine formulation, the outcome measured, the circulating variant, time since vaccination, and the people included in a study. Protection against severe disease can differ from protection against infection or mild illness. Results from different studies or time periods should not be compared as if they were a head-to-head trial.
For current vaccine availability, doses, and personal recommendations, follow the latest guidance from Thai public-health authorities and consult a qualified clinician, especially if you have a medical condition or a history of serious reactions. This overview is educational and is not an individual vaccination recommendation.