A few days ago, the European Medicines Agency (EMA) concluded that unusual blood clots with low platelets can be a very rare side effect of the AstraZeneca vaccine against COVID-19 that, as such, should be included in the package leaflet. In addition, he recalled that the balance between benefit and risk when getting vaccinated is still positive.
Faced with the alarm generated, many experts are trying to explain what this balance of risk versus benefit really means. A team from the University of Cambridge has published graphs, with data based on the incidence rate of COVID-19, in which they reflect this calculation divided into age groups. Although the analysis has been performed using incidence and occupancy data for ICU beds in the UK, the graphs are equally illustrative for people in other countries.
As the authors explain, the main benefits of the vaccine are protection against COVID-19 (both in the short term and from suffering what has been called “prolonged covid”), both for the vaccinated person and for those with whom it enters in contact, as the chances of the vaccinated person infecting them are reduced. However, these potential benefits change depending on the person’s exposure to the virus (for example, by the prevalence of SARS-CoV-2 locally or by the type of work of the person in question) and according to the possibility of contracting a serious infection (depending on age or previous pathologies).
To illustrate the potential benefits of being vaccinated, the scientists chose as a variable the estimated number of ICU hospitalizations avoided by the vaccines and according to the age group against the most serious damage from the vaccine, which would be that of the thrombi in question. In addition, three possible levels of exposure to the virus were chosen, using incidence data by number of inhabitants and illustrating the benefits accumulated over 16 weeks.
Low exposure risk
Illustration of the potential benefits and harms of low exposure to the virus ( incidence of 2 per 10,000 inhabitants per day ). The data on adverse reactions to the vaccine has been taken from the report number of cases of blood clot reactions provided by the Regulatory Agency for Medicines and Health Products of the United Kingdom on March 31, 2021.
Medium exposure risk
Illustration of the potential benefits and harms with an average exposure to the virus ( incidence of 6 per 10,000 inhabitants per day )
High exposure risk
Illustration of the potential benefits and harms of high exposure to the virus (incidence of 20 per 10,000 inhabitants per day )
