The mRNA vaccines from Pfizer-BioNTech (NYSE:PFE/NSDQ:BNTX) and Moderna (NSDQ:MRNA) appear to work well as a second dose in recipients of a single dose of the AstraZeneca (LON:AZN) AZD1222 vaccine. A report in Lancet found that two doses of AstraZeneca’s AZD1222 vaccine were 50% effective. Recipients who received a dose of the AZD1222 vaccine followed by…