The flu vaccine has a new campaign every year, mobilizing health posts across the country. This happens because the virus that causes the disease has an expressive rate of genetic mutations, requiring that vaccines have their composition revised periodically so that their effectiveness is maintained.
Defining the composition of the vaccine is not at all simple: around the world, a hundred National Influenza Centers (NICs) are permanently monitoring the genetic changes of the virus, based on the analysis of patient samples, and supply data from the Global Influenza Surveillance and Response System of the World Health Organization (WHO).
In Brazil, the Laboratory of Respiratory Virus and Measles at Instituto Oswaldo Cruz (IOC/Fiocruz) fulfills this role, as a national reference for influenza with the Ministry of Health, in a permanent work of investigation of the genetic profile of the virus articulated with the Adolfo Lutz Institute (SP) and the Evandro Chagas Institute (PA). At the IOC, the team led by virologist Marilda Siqueira - who has almost 40 years of experience in respiratory viruses - analyzes samples sent by sentinel units spread across all regions of the country.
In addition to following the evolution of the different groups of Influenza, through phylogenetic analyses, the researchers work to identify variant strains of the viruses that circulate during seasonal epidemics - those that happen every year, mainly in winter.
In 2017 alone, the National Influenza Centers collected and tested more than three million clinical specimens from patients. This information is shared with the Collaborating Centers on the WHO topic.
"In the Collaborating Centers, which are international laboratories of high complexity, present in the United States, England, China, Japan and Australia, scientists carry out advanced genetic analyzes seeking to understand the dynamics of circulation of Influenza viruses", explains Siqueira.
"All countries with National Influenza Centers are part of this highly complex gear, which allows us to protect the population most vulnerable to the virus by formulating vaccine compositions updated with the genetic profile of the virus that is in circulation", completes the researcher Fernando Motta, who works at the same Laboratory.
Marilda Siqueira and Fernando Motta work at the Laboratory of Respiratory Virus and Measles at Instituto Oswaldo Cruz. Photo: Gutemberg Brito/IOC/Fiocruzi
To define the composition of the vaccines that will be applied in the next influenza seasons, the WHO holds meetings with an advisory group of experts twice a year.
The meetings take place between the months of February and March to discuss recommendations for the northern hemisphere and, in September, for the southern hemisphere. During the meetings, specialists analyze surveillance data produced by the National Influenza Centers, in addition to information on the genetic characterization of viruses and serology studies in humans with inactivated virus vaccines.
The group also evaluates data on resistance to antiviral drugs and results on the effectiveness of the vaccine used in the current and previous seasons. Based on the set of analyses, the WHO issues, at the end of the meetings, the recommendation of the strains that should compose the immunizer.
The document is used by national vaccine regulatory agencies and pharmaceutical companies to develop, produce and license vaccines against the virus. Seasonal epidemics are mainly caused by variations of three Influenza viruses: two type A (the H1N1 and H3N2 subtypes) and one influenza B subtype (which, in turn, splits between the Yagamata and Victoria lineages).
The trivalent influenza vaccines are constructed to cover these three variations, always considering the genetic profile of the predominant viruses in the previous season. Quadrivalent vaccines, on the other hand, have an identical formulation, with the addition of the remaining influenza B strain.
The flu vaccine has a new campaign every year, mobilizing health posts across the country. This happens because the virus that causes the disease has an expressive rate of genetic mutations, requiring that vaccines have their composition revised periodically so that their effectiveness is maintained.
Defining the composition of the vaccine is not at all simple: around the world, a hundred National Influenza Centers (NICs) are permanently monitoring the genetic changes of the virus, based on the analysis of patient samples, and supply data from the Global Influenza Surveillance and Response System of the World Health Organization (WHO).
In Brazil, the Laboratory of Respiratory Virus and Measles at Instituto Oswaldo Cruz (IOC/Fiocruz) fulfills this role, as a national reference for influenza with the Ministry of Health, in a permanent work of investigation of the genetic profile of the virus articulated with the Adolfo Lutz Institute (SP) and the Evandro Chagas Institute (PA). At the IOC, the team led by virologist Marilda Siqueira - who has almost 40 years of experience in respiratory viruses - analyzes samples sent by sentinel units spread across all regions of the country.
In addition to following the evolution of the different groups of Influenza, through phylogenetic analyses, the researchers work to identify variant strains of the viruses that circulate during seasonal epidemics - those that happen every year, mainly in winter.
In 2017 alone, the National Influenza Centers collected and tested more than three million clinical specimens from patients. This information is shared with the Collaborating Centers on the WHO topic.
"In the Collaborating Centers, which are international laboratories of high complexity, present in the United States, England, China, Japan and Australia, scientists carry out advanced genetic analyzes seeking to understand the dynamics of circulation of Influenza viruses", explains Siqueira.
"All countries with National Influenza Centers are part of this highly complex gear, which allows us to protect the population most vulnerable to the virus by formulating vaccine compositions updated with the genetic profile of the virus that is in circulation", completes the researcher Fernando Motta, who works at the same Laboratory.
Marilda Siqueira and Fernando Motta work at the Laboratory of Respiratory Virus and Measles at Instituto Oswaldo Cruz. Photo: Gutemberg Brito/IOC/Fiocruzi
To define the composition of the vaccines that will be applied in the next influenza seasons, the WHO holds meetings with an advisory group of experts twice a year.
The meetings take place between the months of February and March to discuss recommendations for the northern hemisphere and, in September, for the southern hemisphere. During the meetings, specialists analyze surveillance data produced by the National Influenza Centers, in addition to information on the genetic characterization of viruses and serology studies in humans with inactivated virus vaccines.
The group also evaluates data on resistance to antiviral drugs and results on the effectiveness of the vaccine used in the current and previous seasons. Based on the set of analyses, the WHO issues, at the end of the meetings, the recommendation of the strains that should compose the immunizer.
The document is used by national vaccine regulatory agencies and pharmaceutical companies to develop, produce and license vaccines against the virus. Seasonal epidemics are mainly caused by variations of three Influenza viruses: two type A (the H1N1 and H3N2 subtypes) and one influenza B subtype (which, in turn, splits between the Yagamata and Victoria lineages).
The trivalent influenza vaccines are constructed to cover these three variations, always considering the genetic profile of the predominant viruses in the previous season. Quadrivalent vaccines, on the other hand, have an identical formulation, with the addition of the remaining influenza B strain.
Cover image: Flickr Creative Commons
The non-profit reproduction of the text is allowed as long as the source is cited (Comunicação / Instituto Oswaldo Cruz)
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