Personally I was keen to understand the current efficacy of the main vaccines on the market – and so went back to primary data sources to compile the below table. The cost estimate is very rough – and comes from data accidentally shared by an EU minister in December.
|Pfizer / BioNTech (mRNA)||1st dose: 52%
2nd dose: 95%
|Moderna (mRNA)||2nd dose: 94.1%||-20°C||~$18|
|Oxford / AstraZeneca (Viral vector)||2nd dose: 70.4%||4°C (fridge temp)||~$2.20|
Have omitted other vaccines for the time being as they’re not being rolled out in EU/USA – but that will change in 2021.
Data Around Efficacy Results
See BMJ article, which summarizes NEJM source. Notably 43,548 participants were randomized to 2 groups; placebo and vaccine. There were 8 cases of Covid-19 after 2nd dose in the vaccine group, versus 162 in placebo. Of the 10 total severe cases, 1 was in the vaccine group, versus 8 in the placebo group.
See NEJM article on phase 3 results. Notably, 30,420 participants were randomized to 2 groups, placebo and vaccine. There were 11 cases of Covid-19 after 2nd dose in the vaccine group, versus 185 in placebo. Of the 30 total severe cases, all were in the placebo group, with 1 death.
See Lancet article. Excuse me for interjecting a bit of editorial here, but whereas the data for the Pfizer and Moderna vaccines appears relatively simple to analyze, it’s a bit more convoluted for the Oxford vaccine. This is because the data for their 11,636 participants was split into 2 different dosage groups. The largest group (8,895 – randomized into placebo and vaccine groups) took 2 standard doses, and reported 62.1% efficacy. Whereas the smaller group (2,741 – randomized into placebo and vaccine groups) took a 1/2 dose, then a full dose, and reported 90% efficacy. They then combined the 2 results to calculate an overall efficacy of 70.4%.
Whilst it’s not impossible it’s more effective when starting with a half dose, the current plan (as I understand) is to vaccinate people using full doses. Whilst 70.4% efficacy may sound mediocre compared to the mRNA vaccines, for context the CDC reports the flu vaccine has an efficacy between 40-60%.
Note: Last checked efficacy data mid December 2020 – it’s likely that for the AstraZeneca vaccine, more efficacy data will be emerging in early 2021.