The COVID-19 vaccine typically takes a few weeks after vaccination for the body to produce an effective immune response, including T-lymphocytes and B-lymphocytes. This means it generally takes a couple of weeks for protection to build up after receiving the vaccine dose.
More specifically, effectiveness against COVID-19-associated emergency department or urgent care visits has been observed to be measurable within the first 7 to 119 days after vaccination, indicating that protection begins to show within the first week but builds over time.
The immune system's response includes the production of antibodies to the spike protein (which is made after vaccination), and these spike proteins last in the body for a few weeks before being cleared. The vaccine mRNA itself degrades within a few days, but the immune memory and antibody response take longer to mature.
In summary, full effectiveness generally develops over about two weeks after vaccination, with immunity continuing to strengthen during that period and remaining for several months thereafter.
