Dose booster of anti-Covid vaccine, efficacy and antibodies: that’s who the additional administration is needed for

A third dose of the Covid vaccine it is considered necessary because it has been seen how, despite the effectiveness of vaccines in use remains high against severe Covid-19 disease, that against infection (contagion) decreases over time. What is certain is that antibodies decrease and during the winter the possibility of contagion increases: this is why it was decided to be cautious by planning a third dose or a booster. It is unknown what will happen over the next six months and those at greatest risk are placed in safety.

The plan for the administration of the third dose of the vaccine has already been defined: after the call of the over 80s (4.3 million) and together with the staff and guests of the RSA (half a million), underway on the basis of the circular of the ministry of at the end of September, these days it’s up to healthcare professionals, pharmacies, parapharmacies and professional offices, starting from over 60, to frail (suffering from various chronic and serious diseases, such as cystic fibrosis, diabetes, obesity, cardiovascular, cerebrovascular and hepatic diseases) of all ages e to over 60s in general (as per the circular of 8 October).

The next ones for whom the call is prepared are those immunized with the only single-dose vaccine, the Janssen di Johnson&Johnson: 1,488,585 people, of which about 750,000 are over 60 years old. Then the teachers who, vaccinated with the first and second dose already at the beginning of the year, are pressing to be called as soon as possible for the third: on the one hand they fear the decline in the vaccine’s ability to protect them from the virus, on the other the special conditions of their work, in contact with large groups composed only in part by vaccinated, the pupils.

Thus, the programming of the third doses, therefore, should follow that adopted for the first. Precisely in consideration of the studies that monitor the immune response and its resistance over time.

Circular from the ministry: third dose for over 40s from 1 December

Official green light for the third dose of the anti Covid vaccine, also for the 40-59 age group from 1 December, six months after the last administration. This is foreseen by a circular from the Ministry of Health signed by the Director General of Prevention Gianni Rezza. The document provides that “without prejudice to the priority of vaccination of subjects still waiting to start / complete the primary vaccination cycle, as well as the administration of the” booster “dose (booster) to the categories for which it is already recommended, starting from 1 December 2021 it will also be possible to proceed with the administration of the “booster” dose, with m-RNA vaccine, even to subjects aged between 40 and 59 years, in the dosages authorized for the same (30 mcg in 0.3 mL for Comirnaty of Pfizer / BioNTech; 50 mcg in 0.25 mL for Spikevax of Moderna), provided that at least six months have passed since the completion of the primary vaccination course, regardless of the vaccine previously used “.

– The Aifa Faq –

Why was an additional dose of vaccine needed?

The available evidence shows that solid organ transplant or immunosuppressed subjects exhibit a reduced antibody response following a full course of primary vaccination (two doses of Comirnaty, Spikevax, Vaxzevria and one dose of COVID-19 Janssen vaccine). In these people, who are considered particularly vulnerable due to the increased risk of serious disease, the additional dose of vaccine aims to ensure a better immune response and, therefore, increase protection against COVID-19.

What evidence is based on the need for the additional dose in people with organ transplantation or immunosuppressive conditions?

The data, although still partial and mainly referring to people with solid organ transplantation, show in adult subjects with immunosuppressive conditions following a complete vaccination course a reduced antibody response compared to that observed in healthy adult subjects. Several clinical studies, mainly conducted in an academic setting and of limited size, have shown that administration of a third dose of mRNA vaccine in this population of subjects can significantly increase the antibody titer and the percentage of subjects with seroconversion.

For whom is it appropriate to consider an additional dose right away?

An additional dose of COVID-19 vaccine upon completion of the vaccine cycle may be considered in adults and adolescents aged> 12 years (Comirnaty vaccine) or> 18 years (Spikevax vaccine) in clinically relevant immunosuppressive condition. Solid organ transplant recipients and subjects presenting, on the basis of clinical evaluation, an assimilable level of immunocompromise fall into this category.

What vaccines are used?

In all cases the additional dose should be based on one of the two mRNA vaccines authorized in Italy (Comirnaty and Spikevax). This even if a first vaccination with adenoviral vaccine (Vaxzevria and COVID-19 Vaccine Janssen) had been performed. Furthermore, in the event that the same mRNA vaccine used for the first two doses is not available, an additional “heterologous” dose may be used with the different type of mRNA vaccine. Based on current knowledge, the recommended dosage for the additional dose is the same as the authorized dosage for the primary course.

How long after the second dose should the additional dose be given?

In subjects undergoing organ transplantation or with immunosuppressive conditions, the dose
additional dose should be given at least 28 days after the last dose of the cycle
primary vaccination.

Is it safe to receive an additional dose of the vaccine? Is there enough data to prove this?

Preliminary data on the tolerability of the third dose of mRNA vaccine are based on studies of limited size and show a similar safety profile to the safety profile observed after the first or second dose. This both in terms of the type and frequency of local (pain and redness at the injection site) and systemic (fatigue, headache, chills, muscle and joint pain, fever) side events.

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