«All the vaccines available today in Italy are effective and safe. There is no time to wait for the ideal one. The virus runs and you have to protect yourself. Science has worked a miracle ». Giuseppe Ippolito, scientific director of Spallanzani and member of the CTS technical-scientific committee, wants to dispel the doubts of the “hesitants”, of all those who do not “trust”.
How is the effectiveness of a vaccine established?
«For over a century, the efficacy of a vaccine has meant the extent of the onset of the disease in vaccinated compared to non-vaccinated people. For this, clinical studies are conducted in which volunteers are assigned in such a way random to the group receiving the vaccine or to the group that will not have it and will take a placebo. However, the effectiveness in the field is different, which is defined as practical effectiveness (effectiveness in English): is the measure of how well a vaccine works in a larger population. The efficacy of a vaccine is expressed as the proportion of the attack rate of the disease between the unvaccinated and the vaccinated or as a calculation of the relative risk of disease in the vaccinated group “.
AstraZeneca’s vaccine efficacy is 60 percent versus 90-95 percent for the other two now available, Moderna and Pfizer-Biontech. There is a fear that the people to whom the preparation of the Anglo-Swedish company will be proposed will be wary. Are they right?
“At this stage of the epidemic, I believe that all vaccines that demonstrate relatively good efficacy and relatively good we mean at least 60% -70% should be accepted without hesitation. It is a principle all the more valid if it is accompanied by an adequate safety profile, namely the absence of serious undesirable effects “.
So shouldn’t we back off and wait for more consolidated defense tools?
“It is not possible to wait for the ideal vaccine. The virus must be closely tracked and beaten on time. The choice of reserving vaccines with a higher level of effectiveness for people with a higher age and who have greater risks due to concomitant diseases is the best strategy to better protect those who are most closely in danger of serious disease and death. For those who are less at risk, the other available vaccines are also good ”.
Does messenger RNA technology (genetic information is introduced into the cell envelope to produce antibodies against the virus) seems to have given better results than the traditional viral vector technology?
“It is true, Pfizer and Moderna vaccines have shown a higher efficacy (about 95%) than that with a viral vector, which is used only for the transport of the antigen against which the organism will develop an immune response. Clinical trials for the latter using the traditional system give efficacy levels ranging from about 60 percent to 92 percent of the Russian Gamaleya vaccine. AstraZeneca, which uses the traditional system, achieves an effectiveness that varies and reaches up to 82 percent with two doses administered twelve weeks apart. The Johnson & Johnson vaccine with a single dose reaches 72% ».
Are better preparations on the way?
«It is necessary to continue the evaluation studies of the other 64 vaccines in the clinical phase to decide how and when to use the different technologies. The important thing now is to keep research going, which was able to give concrete answers in a short time. A true miracle of science ».
Does the immune system of the elderly work poorly?
«The efficacy of vaccines in general in the elderly is not very well studied. In these people there is the phenomenon called “immunosenescence”, that is the decline of immunity with age. This determines both quantitative and qualitative modifications of the immune response which can affect efficacy. These changes mainly concern a type of immunity, the cellular one referred to as T. Then there is another type of immunity, called humoral, B. If this works less antibodies are produced.
So the most fragile could be the least strong in the face of Sars-CoV-2 even if immunized?
‘Vaccines are likely to be somewhat less effective in older people. But we don’t know the real impact. Not all Sars-Cov-2 vaccine studies have included an adequate number of seniors. It is another reason to continue research on the elderly. At the moment, the data of the various studies lead to optimism both for the levels of efficacy levels and for the undesirable effects ».
February 6, 2021 (change February 6, 2021 | 21:12)
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