A study of over 2,000 hospital staff indicates that, in those who fall ill after vaccination, the infection has a shorter duration, while the immunity is stronger and more lasting than natural infection
In vaccinated subjects, immunity to the SARS-Cov-2 virus is stronger and more lasting than that naturally developed by those who contract the virus and, in general, is linked to the level of circulating antibodies that are formed in each of us. The confirmation comes from a monitoring study on a significant sample of the health population throughout the period of Covid-19, conceived and implemented by the European Institute of Oncology (Ieo) in Milan and funded by the Guido Venosta Foundation.
The survey of 2 thousand hospital employees
For the research over 2 thousand employees and collaborators of the Ieo
operating in the health, administrative and research fields, underwent (in the period from May 2020 to September 2021) molecular tests for SARS-CoV-2 infection and serological tests to measure the immune response against the virus. With the start of the vaccination campaign in January 2021, the same people were vaccinated and monitored monthly after vaccination, until September 2021. The program involved the execution of 52,800 molecular tests and 20,200 serological tests. “We have observed that the level of circulating anti-SARS-CoV2 antibodies is a reliable indicator of the risk of infection – comments Pier Giuseppe Pelicci, director of Ieo research and coordinator of the study -. The correlation between low antibody levels and increased risk of infection was obtained in the whole vaccine population and on retrospective data. It therefore does not yet have a predictive value in the single individual. On the other hand, it could be very useful if applied, for example, to populations of individuals exposed to a high risk of infections or more fragile. “The results also show that the vaccine works well: the infection rate in the population studied has increased from 17.8% before vaccination to 1.5% after vaccine. Furthermore, the vaccinated who contract the virus have limited contagion capacity because the viral load is very low and lasts a few days.
The infection lasts less with the vaccine
In the pre-vaccination phase, 266 people with SARS-CoV-2 infections were observed, i.e. 17.8% of the 1493 people tested in the pre-vaccination phase. Among the approximately 2 thousand subjects who were vaccinated, only 30 cases of infection were identified (1.5%), which in all subjects presented with minimal symptoms and very limited contagion capacity due to viral load and duration of the contagious phase. The molecular test was in fact positive on average for only two days instead of the average 16 days of an infection in unvaccinated subjects, with obvious implications on the spread of the infection. Immunized people developed high levels of circulating antibodies as early as one week after the first vaccine dose. Only 1.9% (39 cases) of subjects did not develop a measurable antibody response. The extent of the antibody response was lower in the elderly, with a general tendency to progressively decline in the months following vaccination. Nonetheless, within 6-7 months of vaccination completion, 94% of the individuals tested still had measurable antibody levels in their blood. Analyzing in detail the 30 cases of post-inoculation infection, a correlation emerged with the lack of or inefficient antibody response to the vaccine: three cases were subjects who had not developed antibodies in response to the vaccine, while 74% of the other cases were subjects with lower antibody levels than the entire study group. In other words, the post-vaccine infection was contracted from those with the lowest antibody levels.
Stronger immunity
“Overall, the frequency of infection in subjects who developed antibodies after vaccination was significantly lower (1.5%) than in vaccinated subjects who did not develop antibodies (5.7%), but in both cases lower than in unvaccinated subjects who contracted a natural infection (9%) – adds Pelicci -. The vaccine, therefore, induces a stronger immunity than natural infection. “” I hope that the results of this study can dispel the doubts of those who still do not believe in the proper functioning of vaccines, and that serological tests are used in scope of targeted vaccination campaigns – comments Giuseppe Caprotti, president of the Guido Venosta Foundation -. The spirit that animated the program is based on the importance of scientific research whose aim is to improve the living conditions of man. Research has always been part of my family’s DNA. My grandfather, Guido Venosta, was in fact one of the architects of the AIRC (Italian Association for Cancer Research), which he managed from 1966 to 1996. The Foundation continues in this direction, helping to raise the education of the public towards highest cultural, scientific and solidarity ideals ».
November 10, 2021 (change November 10, 2021 | 16:35)
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