The study in Israel on over 80,000 vaccinated people confirms the decline in vaccination efficacy on infections (hospitalizations and deaths have not been evaluated). Six-month positive rate among vaccinated at 15.5%
That the anti Covid vaccines are not neutralizing and immunity decreases with the passage of time documented by numerous studies. A research just published on the British Medical Journa
L conducted on 80 thousand people in Israel, one of the first countries in the world to start the vaccination campaign but which saw a resumption of infections in December 2020, confirms this trend.
it emerged that the Pfizer vaccine provides excellent protection in the first few weeks after vaccination, but the risk of contagion for vaccinated in all age groups begins to increase 90 days after the second dose and it grows more and more as time goes by. The research was conducted to estimate the effect of time since vaccination on the risk of testing positive for a Sars-CoV-2 swab after the second dose. The work focuses on infections and does not assess their severity in terms of the need for hospitalization or mechanical ventilation or mortality.
The results
The study was carried out by researchers from Leumit Health Services and is based on an examination of the electronic medical records of 83,057 adults (average age 44) who were subjected to molecular swabs at least three weeks after the second dose of vaccine between May and September. and who had never previously shown signs of SarsCoV2 infection. Those who had contracted Covid before the study and those who had already received the third dose of the vaccine were excluded.
The results show that 7,973 participants (9.6% of the total) tested positive for the swab, almost all with Delta variant. The analysis shows that, after the second dose of vaccine, the rate of positivity increases over time: equal to
1.3% between 21 and 89 days,
2.4% between 90 and 119 days,
4.6% between 120 and 149 days,
10.3% between 150 and 179 days
15.5% after 180 days.
Compared to the first 90 days after the second vaccine dose, the risk of infection 2.37 times higher after 90-119 days,
2.66 times higher after 120-149 days e
2.82 times higher over 150 days.
The researchers acknowledge that the interpretation of the data is limited by the observational design of the study and that the influence of other factors not considered in the analysis such as virus strain, number of family members and population density cannot be excluded.
In any case, the study was conducted on a large number of people who received the same vaccine, so the results are robust enough to conclude that the protection induced by the two vaccine doses of Pfizer-BioNTech decreases over time and the risk of contagion increases. progressively after the first three months. The results suggest that consideration of a third dose of the vaccine in the near future may be warranted. In Italy it has just been decided to proceed with the third dose for all over 18s at least 5 months after the second dose.
November 25, 2021 (change November 25, 2021 | 14:23)
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