Every year, precise as clockwork, the flu virus arrives to claim several victims. We are well aware that these pathogens have existed for many years, so much so that anti-flu vaccines are certainly not new in recent times. Influenza is considered one of the most common viruses and the death rate is generally low, although there have been some very dangerous variants in the past. Here’s everything you need to know about flu vaccines and this terrifying seasonal disease. The first vaccine in the world
Thanks to the first isolation of the influenza virus – which took place back in 1933 – it was possible to develop the very first vaccine with live attenuated viruses. In those years the inactivated influenza vaccine of the monovalent type was produced: it concerned influenza A. Only in 1942, a bivalent vaccine was created. In 1973, the vaccine breakthrough
The real breakthrough, however, began in 1973, at which time the World Health Organization began publishing annual recommendations for the composition of the influenza vaccine. Scientists, in fact, realized that a single vaccine was not enough because the viruses changed from year to year. Then, in 1978 – five years later – the trivalent vaccine was released – the first one that contained both type A and type B flu strains.Every year we risk big without vaccines
Every year we are at risk of the flu. Why this happens, despite the fact that many of us get vaccinated
In reality every year the virus is slightly different because mutations are implemented in the proteins found on its surface. This means that our antibodies fail to recognize the pathogen and try to fight it as if it were completely new. There are also cases where the mutations are worse than others and the virus is the result of the hybridization of two virus strains. The first flu vaccine
Smorodintseff, in Russia, was the first to experiment with an in vivo vaccine. During this experiment he realized that the modified virus caused a minimally perceptible fever, and that the subjects were protected against reinfection. From then on, mass production of a live, attenuated vaccine began which was widely used by factory workers. It is important to underline that the evaluation methods were not reliable because they are based on self-reported flu episodes, without any control. On the other hand, this type of vaccine has been widely used in the USSR for over 50 years, administered to more than a billion people until the end of the 20th century. ‘Since that time, several attempts have been made in other countries to develop new live attenuated influenza vaccines; however, the unpredictability of influenza viruses remains a problem. Therefore, although it is relatively easy to obtain less virulent viruses after several passes, as Smorodintseff did, these variants are not stable and quickly recover their virulence, which precludes their use in vaccines. The genome structure of these attenuated viruses has been determined and studies to evaluate the risk of reversion lead to the selection of sufficiently attenuated and stable strains to meet the conditions necessary to be used in a live attenuated vaccine, ‘explains Hannoun to MedScape. these variants are not stable and rapidly recover their virulence, which precludes their use in vaccines. The genome structure of these attenuated viruses has been determined and studies to evaluate the risk of reversion lead to the selection of sufficiently attenuated and stable strains to meet the conditions necessary to be used in a live attenuated vaccine, ‘explains Hannoun to MedScape. these variants are not stable and rapidly recover their virulence, which precludes their use in vaccines. The genome structure of these attenuated viruses has been determined and studies to evaluate the risk of reversion lead to the selection of sufficiently attenuated and stable strains to meet the conditions necessary to be used in a live attenuated vaccine, ‘explains Hannoun to MedScape.
Flu vaccine – Photo Chompoo Suriyo shutterstockr How effective is a flu vaccine
According to recent clinical studies, it was possible to demonstrate the effectiveness of the vaccine to prevent first infection, particularly in younger subjects who did not have natural immunity. ‘Available data suggest that these vaccines do not offer good protection in elderly / adult subjects. Live attenuated vaccines are more complicated to use than other types of vaccines and a number of problems have been identified: instability of attenuation, risk of recombination with wild strains, pre-existing immunity preventing infection from the vaccine strain, and instability of live preparations. These problems have been solved and a vaccine has been authorized in several countries under specific conditions, ie, it should only be used in immunocompetent children of 2-7 years old. ‘ Vaccines for the B virus
Virus type B is slightly different from virus A. However, some observations have changed over time. A decade ago, it was believed that B viruses were less severe, did not cause epidemics and were less mutant. Today, however, we know that some B viruses have caused very serious damage and high mortality rates in all age groups. Furthermore, they caused similar epidemics: in the winter of 2005-2006, 59% of the viruses circulating in Europe were type B. For 25 years, the most widespread B strain was the so-called Victoria, before the advent of the famous Yamagata. first appeared in Japan in the 1990s. For about ten years this strain was the dominant one in every corner of the planet. It is no coincidence that all current vaccines contain this strain. But since 2002, Victoria has reappeared and competed with Yamagata. “Since then, the dominant variety has varied by country and by season. These observations show that it is difficult to predict which strain will appear during the next season, particularly as the two strains can circulate simultaneously during the same season and even within the same country. Since the current vaccine contains only one influenza B strain, it is obvious that misalignment between the vaccine and the circulating strain can often occur. ‘ in particular because the two strains can circulate simultaneously during the same season and even within the same country. Since the current vaccine contains only one influenza B strain, it is obvious that misalignment between the vaccine and the circulating strain can often occur. ‘ in particular because the two strains can circulate simultaneously during the same season and even within the same country. Since the current vaccine contains only one influenza B strain, it is obvious that misalignment between the vaccine and the circulating strain can often occur. ‘What has changed in recent years
“Until recently, it was thought that influenza B did not evolve as much as influenza A, but now it is known that influenza B can undergo great changes and that two strains can circulate simultaneously. This understanding of the evolution of the virus contributed to the evolution of the influenza vaccine from a live-attenuated monovalent vaccine to the last quadrivalent inactivated vaccine. In the next 5 years, quadrivalent inactivated influenza vaccine will become more widely used. Advances in the search for a universal vaccine, targeting a common antigen that is not subject to genetic modification, may change our approach to vaccination against influenza. Meanwhile,We must all get vaccinated against the flu
The WHO SAGE panel of experts in the year 2012 made a list of people who should get the flu shot every year: pregnant women, health professionals, children aged between 6 months and 5 years and the elderly over the age of 65. Finally, there are some people who – due to health problems, should get vaccinated. Here’s what they are:
- people suffering from chronic respiratory diseases (including severe asthma, bronchopulmonary dysplasia, cystic fibrosis and chronic obstructive bronchopathy – COPD)
- of diseases of the cardio-circulatory system, including congenital and acquired heart disease
- diabetes mellitus and other metabolic diseases (including obese with BMI> 30)
- chronic renal / adrenal insufficiency
- of diseases of the hematopoietic organs and hemoglobinopathies
- of tumors
- congenital or acquired diseases involving deficient antibody production, drug-induced immunosuppression or HIV
- of chronic inflammatory diseases and intestinal malabsorption syndromes
- of pathologies for which major surgical interventions are planned
- of diseases associated with an increased risk of aspiration of respiratory secretions (e.g. neuromuscular diseases)
- of chronic liver diseases.
- of children and adolescents on long-term treatment with acetylsalicylic acid, at risk of Reye’s Syndrome in case of influenza infection.
- individuals of any age admitted to long-term care facilities
The composition of the influenza vaccine
The WHO Global Influenza Surveillance Network, in collaboration with the National Influenza Centers (NIC), updates the composition of the influenza vaccine every year in order to prevent or mitigate any epidemics. Last year, the vaccine was composed of the following viruses: A / Michigan / 45/2015 (H1N1) pdm09, A / Singapore / INFIMH-16-0019 / 2016 (H3N2), B / Colorado / 06/2017 (lineage B / Victoria) and B / Phuket / 3073/2013-like (lineage B / Yamagata). This year, in a very similar way, the vaccine will contain variants of the same strains:
– a new antigenic variant of subtype H3N2 (A / Singapore / INFIMH-16-0019 / 2016) which replaces the A / Hong Kong / 4801/2014 strain, and a new antigenic variant of type B (B / Colorado / 06/2017 ), lineage B / Victoria, which will replace the strain B / Brisbane / 60/2008. How to carry out the vaccine
The vaccine is free for all subjects at risk and costs about 20 euros for all categories of people who are not included in the list drawn up by the WHO SAGE. It can be performed at your family doctor, at health facilities or, in some cases, even at the workplace by the occupational doctor. Administration is via intramuscular injection in the upper arm. In young children it is performed in the anterolateral thigh muscle in children.The objectives of vaccination
According to a recent circular from the Ministry of Health, the objectives of vaccination are: Therefore, the objectives of the seasonal flu vaccination campaign are:
- the reduction of the individual risk of illness, hospitalization and death
- the reduction of the risk of transmission to subjects at high risk of complications or hospitalization
- the reduction of social costs associated with morbidity and mortality
Influenza vaccine and Guillain Barre syndrome (GBS)
Guillain Barre syndrome is an acute immune-mediated disease of the peripheral nervous system which manifests itself with extreme muscle weakness up to paresis / paralysis. Cases of GBS commonly occur following a gastrointestinal infection or an acute respiratory infection including influenza so influenza vaccination can effectively reduce the overall risk of GBS by preventing influenza. Data on the association between GBS and seasonal flu vaccination are variable and inconsistent across all flu seasons. If there is an increased risk of GBS after flu vaccination, it is small, on the order of one or two additional GBS cases per million doses of flu vaccine given.The side effects of the vaccine
Many fear the side effects of flu vaccines. Indeed, like any other drug, they may produce unwanted effects. Which, in most cases, fade away quickly. ‘Inactivated vaccines, given by intramuscular injection, can commonly cause local reactions such as pain and redness at the injection site and, less often, fever, muscle or joint pain or headache. These symptoms are generally mild and do not require medical attention, resolving with symptomatic treatments (antipyretics, analgesics) within a couple of days. Fever, aches and headaches can occur more frequently in children and young people than in older people. Influenza vaccines based on inactivated viruses can rarely cause allergic reactions such as hives, rapid swelling at the injection site, asthma or severe systemic (generalized) allergic manifestations due to hypersensitivity to certain components of the vaccine “, state the experts of the Ministry of Health. Reactions generally occur a few hours after administration and last on average 1 or 2 days.Who cannot get vaccinated
In reality, since these are dead viruses, there are no contraindications to the flu vaccine, even for immunosuppressed subjects. It is not advisable to get the vaccine only under 6 months (lack of clinical evidence) and during an infectious disease (even a common cold). On the other hand, it can also be done in case of egg protein allergy, during breastfeeding and in patients with HIV. Scientific sources
[1] MMWR Recomm Rep. 2003 Sep 26; 52 (RR-13): 1-8. – Using live, attenuated influenza vaccine for prevention and control of influenza: supplemental recommendations of the Advisory Committee on Immunization Practices (ACIP). – Harper SA1, Fukuda K, Cox NJ, Bridges CB; Advisory Committee on Immunization Practices.
[2] Kendal AP, Phillips DJ, Webster RG, Galland GG, Reimer CB. Effect of test system on the ability of monoclonal antibodies to detect antigenic drift in influenza A (H1N1) virus haemagglutinins. J. Gen. Virol., 54 (Pt 2), 253-261 (1981).
[3] J Clin Invest. 1945 Jul; 24 (4): 547–553. doi: [10.1172 / JCI101634] PMCID: PMC435486 PMID: 16695244 protective effect of vaccination against induced influenza b 1 Jonas E. Salk, 2 Harold E. Pearson, Philip N. Brown, and Thomas Francis, Jr.
[4] Expert Review of Vaccines – The Evolving History of Influenza Viruses and Influenza Vaccines – MedScape
[5] Prevention and control of influenza: recommendations for the 2018-2019 season – Ministry of Health
[6] FAQ – Influenza and influenza vaccination – Ministry of Health
[7] Kendal AP, Phillips DJ, Webster RG, Galland GG, Reimer CB. Effect of test system on the ability of monoclonal antibodies to detect antigenic drift in influenza A(H1N1) virus haemagglutinins. J. Gen. Virol., 54(Pt 2), 253–261 (1981).
[8] J Clin Invest. 1945 Jul; 24(4): 547–553. doi: [10.1172/JCI101634] PMCID: PMC435486 PMID: 16695244 protective effect of vaccination against induced influenza b 1 Jonas E. Salk,2 Harold E. Pearson, Philip N. Brown, and Thomas Francis, Jr.
[9] Expert Review of Vaccines – The Evolving History of Influenza Viruses and Influenza Vaccines – MedScape
[10] Prevenzione e controllo dell’influenza: raccomandazioni per la stagione 2018-2019 – Ministero della Salute
[11] FAQ – Influenza and influenza vaccination – Ministry of Health