Influenza Vaccine Algorithm Flu Resources


Widespread especially during the winter season, the flu is classically transmitted by air, through droplets emitted by an infected person with sneezes, coughs or when speaking.

It should be noted that it is possible to contract the flu check it out even by touching surfaces or objects contaminated by the virus if, after having done so, you bring your hands to your mouth, nose or eyes.

Generally, in healthy adults, influenza is a self-healing infection that may only require simple symptomatic therapy; in young children and even more so in the elderly, chronically ill and immune-fragile subjects, on the other hand, it could represent a very serious condition and such as to require the use of antiviral drugs and, above all, hospitalization.

Like all antiviral vaccines

The flu vaccine stimulates an individual’s immune system to produce specific antibodies against the influenza virus.

Antibodies, or immunoglobulins, are globular proteins capable of fighting and inducing the destruction of foreign microorganisms (antigens), which can infect the entire human organism.Like all antiviral vaccines

The antibodies are secreted by particular immune cells, called B lymphocytes, and act as surface antennas of the latter: in the presence of an antigen, the immunoglobulins exposed on the surface membrane of the B lymphocytes are activated, signaling the B lymphocyte itself to produce other specific immunoglobulins against the detected antigen; from here on, the defensive barrier erected by the human immune system becomes increasingly powerful and effective: the B lymphocytes, in fact, produce a large number of antibodies which, circulating through the blood, trace the antigens present in the body and recall all those cells responsible for the destruction of foreign microorganisms (phagocytes and cytotoxic cells).

  • At the end of this process, completely unique B lymphocytes are formed, capable of recognizing more quickly the antigen already encountered (and eradicated) previously, should it recur.
  • These B lymphocytes are also known as “memory cells” and the mechanism by which they are created, called “immune memory”, is the basis of antiviral vaccines such as the flu vaccine.

Generally, the first availabilities start from August/September, i.e. slightly earlier than the ideal time to get vaccinated, which is between the months of October and November, and well in advance of the flu season, which corresponds to winter .

It is good practice to undergo vaccination in the period recommended by doctors, as the vaccine, with the collaboration of the recipient’s immune system, takes two weeks to produce immune memory against the flu virus.

Getting vaccinated late or in the middle of the flu season could be useless, because you run the risk of falling ill when your memory cells are not yet ready.

Adults over the age of 65

Children older than 6 months and teenagers and adults affected by serious pathologies, which increase the risk of complications related to a possible influenza virus infection (e.g.: asthma, cystic fibrosis, COPD, cardiovascular diseases, diabetes, insufficiency kidney disease, tumors, liver disease, liver failure, etc.).

Actually, to be precise, the flu vaccine includes the fragments of the flu viruses that medical-scientific research believes will be more widespread in the coming winter season.

Readers are reminded, in fact, that there are more viruses than influenza and that, annually, one of these viral agents is predominant over the others in terms of diffusion in the general population.

Adults over the age of 65

The injectable variant, consisting only of fractions of the inactivated influenza virus (the viral agent is effectively killed), and

The nasal spray variant, which is made up of fractions of the attenuated influenza virus (attenuated means that the virus is alive, but weakened and unable to cause disease).

Unlike the United States, the United Kingdom and many other European countries, in Italy, only the injectable inactivated flu vaccine is marketed, although the other variant has received the approval of AIFA (Italian Medicines Agency) and the Ministry of Health .

Inactivated Injectable Influenza Vaccine

  • As anticipated, the inactivated flu vaccine is composed of parts of killed virus, completely harmless to the human body, but still able to stimulate the immune system and develop an antibody response useful for immunization against the flu virus.
  • Inactivated influenza vaccine is a somminist drug preparation by intramuscular or intradermal injection.

Both usually carried out on the arm, the intramuscular injection is practicable for all people from 6 months of age onwards, while the intradermal one can be performed only in subjects falling within the age group ranging from 18 to 64 years.

Injectable Inactivated Influenza Vaccine Subtypes

There are two subtypes of injectable inactivated influenza vaccine: the trivalent subtype and the quadrivalent subtype.

The trivalent subtype contains the inactivated antigens of three influenza viruses: two of type A (H1N1 and H3N2) and one of type B; the quadrivalent subtype, on the other hand, contains the inactivated antigens of four influenza viruses: the same two of type A present in the trivalent (H1N1 and H3N2) and two of type B.

These proteins are potential allergens

It should also be noted that the injectable inactivated influenza vaccine is available in four different formulations: split vaccine, virosomal vaccine, adjuvanted vaccine and intradermal vaccine.

Influenza Vaccine Attenuated Nasal Spray

Given intranasally as a spray, attenuated influenza vaccine is made up of small fragments of live but weakened influenza virus; weakened means that its fragments are not capable of causing infectious disease, but are capable of evoking the antibody response useful for immunization against the influenza virus.

These proteins are potential allergens

Precisely because it contains fragments of live virus, the attenuated flu vaccine is not available to anyone (see contraindications); moreover, even when the state of health of the potential recipient is optimal, this vaccination is practicable only in people between 2 and 59 years of age (*).

As previously stated, the attenuated flu virus administered via nasal spray is not marketed in Italy, even if it has received the approval of AIFA and the Ministry of Health; in practice, this means that the traditional pharmacies present in the Italian territory do not sell and provide customers with the aforementioned vaccine preparation.

Severe egg allergy

Egg protein is an ingredient used to prepare most commercially available injectable flu vaccines, regardless of what flu virus is in season. i.e. they can trigger an adverse reaction in allergic or hypersensitive people, characterized by more or less serious symptoms.

Contraindications Influenza Vaccine Attenuated Nasal Spray The use of the attenuated flu vaccine – which is not marketed in Italy – is contraindicated in:

Generally, after the flu vaccine, the patient has to wait 15 to 30 minutes before being able to go home: this is a precautionary measure that healthcare personnel take to ensure that they can intervene promptly in the event of any adverse reaction to the vaccination.

Is it possible to catch the flu even after the vaccine? It can happen that, even after the flu vaccine, a person gets sick with the flu.