The effectiveness of the anti covid vaccine from April to today is confirmed to be very high in reducing deaths (95.7%) and severe forms of the disease that require hospitalization in medical departments (93.1%) and in intensive care (95.4%), according to this report from the Gimbe Foundation. But how long does the covid vaccine really last? In Italy, the administration of the third dose of the vaccine for some categories of fragile and immunocompromised subjects started a few days ago. And in many countries there is discussion about the need or not for an additional administration for all. At the heart of the issue is the duration of protection offered by drugs approved by regulatory bodies and in use for months. Let’s see what the most recent studies say on the duration of the effectiveness of the administration.
How many months does the vaccine protection against covid last
A team from the University of Milan led by clinical pharmacologist Francesco Scaglione is carrying out a study on three thousand people vaccinated in January, just to understand how long the vaccine protection lasts. The first step of the study, three months after vaccination, will be published in the specialized journal Mayo Clinic Proceedings, but the data at six months are also ready. “We evaluate the decrease in the antibody response through the anti-spike IgG – explained the doctor -. We have seen that, while at three months it remains high, at six months it drops considerably in 40-50% of subjects”. The expert admitted that there is no clear-cut correlation between the level of IgG antibodies and effective protection, “but we know from empirical experience that vaccination protects against infection or in any case from serious disease. Even in the presence of few IgG antibodies, in fact, it is possible that, in contact with the virus, a rapid immune response is activated thanks to the lymphocytes “.
The protection offered by the Moderna vaccine
The topic of the third dose of the vaccine related to the duration of the drug’s effectiveness is also under discussion in the United States. According to a study by the US Centers for Disease Control and Prevention (CDC), the Moderna vaccine is the best performing one. The efficacy against hospital admissions is 92% – versus 77% for the Comirnaty Pfizer / BioNTech vaccine – four months after the second dose. The effectiveness drops to 68% after twenty-eight days for the Johnson & Johnson single-dose. Still with regards to Moderna, some researchers from the La Jolla Institute for Immunology, in California, affirm in a work published in Science that the immunity given by the vaccine lasts at least six months in all age groups, and there are no indicators of the need. of a third dose.
How long will immunity last with Pfizer
As for Pfizer, a study carried out by the same pharmaceutical company shows that immunity drops significantly between six to eight months after the second dose. In a report delivered to the Food and Drug Administration (Fda), Pfizer also included data from a survey by the Kaiser Permanente Southern California health consortium, according to which the effectiveness of full vaccination, without the third dose, would drop by 88%. of the first month after the second injection to 47% after five months. Another study published in the New England Journal of Medicine found Pfizer’s effectiveness dropped to 84% four to six months after the second dose.
The effects of the third dose
Those who are already studying the effects of the third dose are Israel, which started administering it in July. What has emerged so far? A study published in the New England Journal of Medicine based on data from the Ministry of Health shows that cases of contagion and serious illness drop substantially. The infection rate, twelve days after the booster, is 11.3 times lower than the two doses, while the severe disease rate is 19.5 times lower. This is a study conducted from 30 July to 31 August on 1.13 million over 60s who had completed immunization five months earlier, divided into two groups (those who received the third dose and those who received it two). The third dose with Pfizer would bring “vaccine efficacy to approximately 95% compared to the Delta variant, a value similar to the original value reported against the Alpha mutation.”