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The coronavirus vaccine developed by Pfizer and BioNTech provides vaccinees with at least 50% protection 10 days after the first shot and is 95% effective one week after the second shot, new data from Israel reveal.
Israel’s data is very similar to the findings from Pfizer’s own Stage III clinical trials.
The findings of the new study are based on a probabilistic statistical model used to analyze vaccination rates and COVID-19 patients in moderate to severe condition – based on a breakdown by age groups in Israel. The study has not yet been peer reviewed.
The model is based on principles drawn from statistical physics and shows that since the second week of January, it is possible to observe a decrease in the rate of new patients in moderate to severe condition among the age group over 60 years – which cannot be other variables.
The research was conducted by Dr Hilla De-Leon, who is doing post-doctoral research at the Trento Institute for Fundamental Physics and Applications under the guidance of Professor Francesco Pederiva from the University of Trento in Italy, and professors Doron Gazit, Ronit Calderon-Margalit and Yinon Ashkenazy of the Hebrew University of Jerusalem.
De-Leon, a theoretical physicist, says she started working on the model used in the study in March of last year when the pandemic started to spread around the world and the situation in Italy turned. deteriorated. His research was originally focused on the computation of multi-body systems that include interactions between all pairs of particles that weaken the further the two particles are from each other.
When COVID-19 started to spread, De-Leon and Pederiva began to adapt their model for epidemiological use. But in this case, the distance between any two particles in the model determines the probability that one of them is infected by the other. De-Leon and Pederiva published their first theoretical model in August in the scientific journal Physics of Fluids.
When Pfizer and Moderna announced the success of their clinical trials, and alongside the cases of reinfection, De-Leon and Pederiva improved their model to include the possible influence of vaccination campaigns and the possibility of reinfection. The second article, “Statistical Mechanics Study of the Introduction of a COVID-19 Disease Vaccine,” was originally posted to the medRxiv Preprint Server for Health Sciences prior to peer review. .
At the end of December, “Doron (Gazit) called me and asked if I could adapt the model to actual data from Israel and the efficiency Pfizer reports in its trials,” De-Leon said. Adapting the model to real field data required a little work. “Now, for each particle in the model, there is a name – its age. This allows an analysis of the infection as a function of age and the adaptation of the model to immunization data in Israel, ”she said.
One problem De-Leon and his colleagues had to resolve was that the scenarios presented by the model went wrong near 1,200 critically ill patients. De-Leon says the solution to this hurdle was understanding that this number was the upper limit on the number of critically ill patients Israeli hospitals could treat.
To find out, De-Leon and his colleagues tweaked the model using infection numbers from the second wave of the outbreak. At this point, they saw that there is a relationship between the daily number of patients in severe and moderate condition and the load on the health system.
This is why the drop in the number of patients in serious condition that occurred at the end of January can also be explained by the crossing of this limit downwards, specifies De-Leon. Places opened in hospitals by patients over 60 in serious condition have been filled by other patients who were not previously considered to be in serious condition. In the third wave, the number of critically ill patients over 60 began to decline from January 15 – just a week after the lockdown was tightened. “The only explanation for this drop is vaccination,” she said.
As of the last data update at the start of the week, the curve of the evolution of the number of patients in moderate and severe condition exactly matches the scenario in which the Pfizer vaccine offers 95% protection against disease. severe after 28 days. “The decrease shows up exactly where the model predicts it will come from,” De-Leon said.
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