2024-01-12 10:29:55
For a few weeks now, respiratory viruses have been attracting attention not only because of the decision of the Ministry of Health of making masks mandatory in health centers until the incidence begins to decrease, but also because this year, the intensity of the flu has increased compared to previous seasons.
According to the latest data published by the Carlos III Health Institute, the percentage of positive samples is 41% and although it decreases compared to the previous week, the transmissibility level is very high in relation to flu epidemics before and after the coronavirus pandemic.
Different flu viruses
There is not only one type of flu virus. There are up to four- A, B, C and D-. The latter only affects animals and C affects both animals and humans, but it is very rare. It is A and B that cause the annual epidemics, as the professor of Preventive Medicine and Public Health at the University of Barcelona, Ángela Domínguez, explains to EFEsalud.
Of the virus that causes gripe A There are two subtypes: the N1H1, which caused the swine flu pandemic in the 2009-2010 season, and arose from the combination of segments of genetic material from swine, avian and human viruses; and the other is the H3N2emphasizes the expert, who is also coordinator of the working group on Vaccination of the Spanish Society of Epidemiology (SEE)
This season, the one that is circulating the most is A and specifically the N1H1 subtype.
B also circulates, but to a lesser extent than A. And the fact is that “when we talk about the circulation of influenza viruses – Domínguez insists – we are not talking about just one but rather several subtypes and types may be circulating.”
SARS-CoV-2 is quite stablealthough it is still there, and the respiratory syncytial virus is beginning to reduce its incidence.
Of the virus that causes influenza Bthere are two lineages, one that is no longer circulating and that is the yamagata and the other is the victoria.
The symptoms
It is difficult to distinguish from the symptoms what type of flu virus it is because It depends a lot on the characteristics of the personas indicated by the professor at the University of Barcelona.
“In principle, influenza A, specifically the H1N1 subtype, could cause more severity than B, but it depends a lot. It cannot be said that one subtype is more serious than the other, because it also depends on the season and the strain that is circulating,” he points out.
The symptoms are similar and the differences are not relevant. We are talking about high fever, sore throat, headache, muscle and joint pain, as well as nasal congestion.
And also very similar to those of covid, although the latter can incorporate those of the loss of smell and taste. Furthermore, fever is not always present.
In older people and those with chronic pathologies, it can have a more serious impact and can trigger pneumonia. It can also affect the nervous system and cause encephalitis, as well as the heart muscle and cause myocarditis.
The best shield, the vaccine
To prevent it, there is the best shield, which is the vaccine, and it is tetravalentthat is, it protects against influenza A and B, with their respective subtypes and lineages (N1H1, N3H2, yamagata and victoria).
As highlighted a EFEsalud the secretary of the Spanish Society of Virology (SEV), director of the WHO Influenza Center and head of the Respiratory Viruses Laboratory at the National Center for Microbiology, Inmaculada Casasthe flu vaccine changes every year, depending on the viruses that have circulated the previous season.
PHOTO EFE/Nacho Gallego
“At the WHO flu center, what we do is find out how much the flu that is circulating has differentiated from the flu or the strains that have been given to the population in the vaccine. There is always a rate or variation. And right now we are doing these types of studies and the one that is circulating the most is N1H1, which is in the vaccine,” explains Casas.
However, he indicates, there is still no sufficiently precise data on how many genetic and antigenic groups are circulating at this time, in order to prepare the vaccine for next season.
To analyze and decide on the vaccine needed for the next season, the WHO laboratories meet in Geneva at the end of February.
EFE/EPA/MARTIAL TREZZINI
“This virological knowledge is what is done to decide whether or not the virus needs to be changed with respect to what has been vaccinated this year in the population,” Casas elaborates.
Types of vaccines
And as he explains a EFEsalud the spokesperson for the Spanish Vaccinology Association, the pediatrician Fernando Moraga-Llopthere are two main types of vaccines: inactivadas (from dead viruses) and that are administered by injection and those of attenuated viruseswhich is the intranasal.
The attenuated ones contain viruses modified in the laboratory in order to weaken them. Neither type can cause the disease in healthy people, but they maintain their ability to stimulate the production of antibodies against it.
Regarding the intranasal vaccine in Europe, it is indicated exclusively for children and adolescents, from 2 to 17 years of age, Moraga-Llop clarifies. In the United States it has a broader indication.
Who is it recommended for?
According to current recommendations of the Interterritorial Council of the National Health System (CISNS) Premature babies and children with at-risk conditions should be vaccinated.
In addition, last October systematic vaccination of children between 6 and 59 months was approved.
Health authorities consider also risk groups a:
Personas 60 years or older.
Pregnant women and women during the postpartum period.
People under 60 years of age with the following risk conditions: chronic cardiovascular, neurological or respiratory diseases, including bronchopulmonary dysplasia, cystic fibrosis and asthma; Mellitus diabetes; chronic kidney disease and nephrotic syndrome; chronic liver disease, including chronic alcoholism; serious neuromuscular diseases; and immunosuppression.
People who can transmit the flu to those who are at high risk of complicationslike caregivers.
Other groups in which vaccination is recommended: They are smokers, health personnel, those who work in essential public services such as Security Forces, firefighters and Civil Protection.
And although it is January and the campaign began at the beginning of autumn, Moraga-LLop indicates that you must get vaccinated while the virus is circulating.
The vaccine begins to be effective fifteen days after its administration.
Complementary measures
But, in addition to the vaccine, there are other complementary measures to avoid contagion and we know them well: the mask, hand hygiene and ventilation of closed spaces.
EFE/ Raquel Manzanares
For the secretary of the SEV, the use of face masks in health centers until the incidence of respiratory viruses begins to decrease, as the Ministry of Health has decided, is necessary.
“The other day they told me that in a hospital there were many people in the emergency room and many of them with respiratory symptoms. Masks work to somehow control the spread of these respiratory viruses that are so easily transmissible. And when people are overcrowded in emergency rooms it is not because they are in good health, and obviously the vulnerable must be protected,” says Inmaculada Casas.
And it justifies its exceptional use due to the incidence of these respiratory viruses such as the flu, obviously, he points out, it should not be worn in the month of August or when things are normalizing.
The coordinator of the Vaccine group of the SEE speaks in the same sense, since although the vaccine is the “most important” preventive technique of all that exists, “it is not an infallible technique” so it must be accompanied with care. measures such as, among others, the use of a mask.
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