3 months after the second dose, the vaccine confirms its effectiveness: it is the result of a study on operators of the Niguarda hospital vaccinated against covid-19.
How long do antibodies really last after vaccine administration? How long will we be protected against covid? There is a great deal of research around the world that is focusing on this key aspect in the fight against the pandemic and, although there is no definitive data yet, the studies carried out suggest that the protection may actually be protracted over time.
And today an Italian research, conducted by the Niguarda Hospital in Milan, in collaboration with the University of Milan, also reports encouraging results. This is the ‘Renaissance’ clinical study, which examined a vast series of cases – the largest to date in Italy – made up of 2,415 health workers in service at the Milanese hospital.
Niguarda, study on vaccinated personnel: 98% have anti-Covid antibodies
The study aims to evaluate the immune response, photographing it at different time intervals. First of all, the response was evaluated 14 days after the second dose (the results were released last March), the research now strengthens with the data 3 months after the completion of the immunization cycle.
All practitioners undergoing the study completed their course with Pfizer / BioNTech’s Comirnaty vaccine between January and February. “With the first analysis we had observed an antibody response in over 98% of the vaccinated – he comments Francesco Scaglione, director of the Laboratory of Chemical Analysis and Microbiology of Niguarda “.
And what happened after 3 months? “After 3 months from the second dose, in all those who had responded positively to the vaccine, the antibody titer in the serum persists – continues Scaglione – As expected, the average values detected naturally decreased over time (by about 50% on average), but however they are still much higher than the negativity threshold. There is still no confirmed data about the cut-off, that is the minimum antibody titre to be protected. We will certainly know more when the study completes its process, which also provides for a dosage at 6 and 12 months later. Meanwhile, the validity of the vaccine is also confirmed by the fact that no one has developed a symptomatic disease during the months of the third pandemic wave “.
Delta variant, British data confirm the efficacy of the second dose of the vaccine
Another interesting fact concerns the hospital’s internal health surveillance. Since the vaccination cycle on over 4,500 employees was completed, none of them have developed symptomatic Covid. Following health surveillance, 14 people were found to be positive, all asymptomatic or paucisymptomatic. “This data is also particularly positive. Considering the circulation of variants, the study suggests that the vaccine can somehow confer protection even in these cases”, concludes Scaglione.
Importantly, however, the antibody response observed now in the research (IgG antibodies directed against the RBD receptor of the Spike protein) reflects only part of the complex protective mechanism activated by the body with the vaccine. In addition to antibodies, in fact, there is the response mediated by cells such as those of memory and natural killer cells, which represent the fundamental elements for prolonged protection over time. “After the first phase of the study, we will investigate the response of T cells, those responsible for memory, to understand if the vaccine can induce a very long-lasting immunity”, concludes the specialist.
Delta variant, British data confirm the efficacy of the second dose of the vaccine
While waiting to analyze how the immune system of Niguarda operators will respond 6 and 12 months after vaccination, the researchers of the Milan hospital also publish further research useful for the vaccination campaign. In this case, with a retrospective analysis, the impact of vaccination on workers was assessed to establish whether the extent of the side effects was such as to negatively affect the hospital’s ongoing activities. Starting from an even larger case history than that of the Renassaince study, with a sample enlarged to 4,043 people, the research reveals that only 1.6% of Niguarda’s professionals had to take time off from work due to side effects (however mild) after the first administration of the Comirnaty vaccine and about 6% after the booster (which as known evokes a stronger response than the first injection). On average, the absences were 2 days and with more pronounced side effects in workers who had previously contracted the virus.
Covid, immunity could last for years
This type of survey demonstrates how a large vaccination campaign within a company does not critically interfere with work activities, confirming once again the importance of the widest possible immunization, which reduces the risk of getting sick to cause of the covid.
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