Vaccinated versus unvaccinated, a comparison between cases shows that the vaccine works

ISS, July 20th 2021 - 

• If vaccinations in the population reach high levels of coverage a paradox occurs, whereby the absolute number of infections, hospitalizations and deaths may be similar among the vaccinated compared to the unvaccinated. However, in such cases, the incidence (intended as the ratio between the number of cases and the population) is about ten times lower in the vaccinated than in the unvaccinated. Therefore, when read correctly, these figures reiterate vaccine efficacy.
• · COVID-19 vaccination, as is the case with all vaccinations, does not protect 100% of vaccinated individuals. We currently know that if the full course of vaccination is administered, the COVID-19 vaccine protects 88% of individuals from infection, 94% from hospitalization, 97% from ICU admission, and 96% from a fatal outcome of the disease.

• It is therefore possible and expected that there will be a limited incidence of infection, hospitalization, admission to intensive care and mortality even among vaccinated individuals, though the numbers will be much lower compared to those reported among unvaccinated individuals.
• · As the vaccination coverage increases, the number of cases decreases due to the efficacy of the vaccination. As a result, the few cases among vaccinated subjects may appear proportionally numerous; in population groups with a very high vaccination coverage, the majority of reported cases could thus occur in vaccinated subjects. This is only because the number of vaccinated individuals is much greater than that of unvaccinated subjects.
• · This is an expected and well-known paradox that must be recognized so as to avoid possible concerns and loss of confidence in vaccination.
• · Moreover, surveillance systems do not directly report on the cases of disease prevented by vaccination. They only reveal cases of individuals who develop the disease despite vaccination.
• · The vaccine provides effective protection to the population when the complete number of doses is administered. However, it should be pointed out that the more the virus circulates, due to a sub-optimal vaccine coverage in all age groups and/or non-compliance with restrictions, for example, the greater the risk that the virus is transmitted to subjects at risk of severe disease, even if vaccinated, and cause the emergence of new variants.