AstraZeneca
Earlier created to be a two dose vaccine, a mistake during one part of the trial resulted in a surprising finding that administering half a dose first and then a full dose second resulted in 90% efficacy vs. 62% efficacy in those getting the two full doses. However, only 2,700 persons were administered the “mistaken” dosage and this requires further study. This leaves AstraZeneca as the vaccine candidate with the least efficacy when compared to the two mRNA vaccine options. Results were based on a 131 case mark with 30 in the control group and 11 in the vaccine group contracting the virus.
AstraZeneca remains the cheapest vaccine at GBP 3/dose and can be stored at room temperature (like most other existing vaccines) allowing health workers to work in a familiar setting.
If you are questioning which vaccine should you take: given what is known of COVID19 (its rapid spread, its attack on the respiratory and vascular systems of the body, long COVID afflicting patients six months post initial recovery and the fatality rate), all of these vaccines appear as attractive alternate options.