According to EMA officials, the exact composition of the tested and mass vaccines differs in many ways, and in particular in the degree of integrity of the mRNA fragments. In the samples for clinical trials, 69% to 81% of the chains were a whole matrix by which the protein can be synthesized from start to finish. On the other hand, batch data produced on new production lines showed lower percentages of whole mRNAs, 59% on average. In some parties, the decline reached 51%. This is what was called the "blocking point" in the November 23 EMA. The outgoing vaccine used a filter that separates full molecules from short cuttings, but it proved difficult to scale up for commercial production.

http://www.personal-view.com/talks/discussion/25116/war-hackers-got-pfizer-covid-19-vaccine-data#Item_2

Using highly restrictive criteria, Osterholm and three other influenza researchers screened more than 5700 studies of the efficacy of vaccines licensed in the USA that had been published since the 1960s. From 31 eligible studies – only those whose endpoints were laboratory-confirmed influenza – they found that on average the seasonal flu vaccine was about 59% effective in individuals aged 18 to 65 years – far lower than the 70–90% previously believed – with at best a 4% reduction in mortality among the elderly. In this case ‘effective’ meant able to prevent laboratory-confirmed influenza, regardless of severity. The study was published in Lancet Infectious Diseases.

Also if you will check charts efficiency for older people (who are prime risk group for coronavirus) is very bad.

So for 2014/15 season: If 5 persons got vaccinated 4 of them would still get sick.