In my last post, I explained that the Pfizer vaccine for children aged 5 to 11 has been slightly modified with respect to an inactive ingredient: the buffer. Buffers are substances that resist changes to pH (the acidity or alkalinity of a solution). Buffers are a very important component of mRNA vaccines (really all vaccines but mRNA vaccines especially) because mRNA does not tolerate alkaline conditions, which the buffer helps to ensure do not occur in the vial. Specifically, under alkaline ...
