Influenza virus type A H3N2, subclade K, has seen an increase in the United Kingdom in recent days. Hospitals there have had an increase in admissions due to this flu, and some schools have even closed to prevent further infections. Although in America only Canada and the United States have reported cases of this variant, the Pan American Health Organization (PAHO) has alerted countries in the region about a possible increase in this and other influenza variants. The first case was confirmed in Mexico on the afternoon of this Friday, December 12.
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It should be noted that on the American continent there are eight countries, including Colombia, that have more than 1,000 cases of one of the variants of the H3N2 virus.
Where does the H3N2 virus come from and what does it mean for it to be type A?
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The A(H3N2) virus subtype emerged in 1968 in Hong Kong, and after several months it moved to the United States. Since then, it has circulated as an influenza A virus and is associated with more severe annual epidemics than those caused by the other influenza A(H1N1) and influenza B viruses. The latest variants that have appeared are those of subclade K, which currently circulate mainly in Europe, with the United Kingdom being the most affected country with 156 registered cases. between August 25 and October 20 of this year.
The influenza virus can cause serious health complications. Photo:Stock
Influenza can be classified as A, B, C or D, with A being the most serious, since it implies that due to its magnitude it can cause a pandemic. Among the most frequent symptoms are: sudden onset of fever, cough, headache, muscle and joint pain, and sore throat.
Alert in America due to increase in cases of influenza and other viruses
Although influenza type H3N2, subclade K, has had a greater presence in Europe, on December 4, the Pan American Health Organization (PAHO) issued an epidemiological alert due to the beginning of the season of greatest circulation of this and other types of viruses. In this report, heThe organization declared that, until epidemiological week number 45, influenza was on the rise, and type A was detected in all regions of the world. Likewise, a 29% increase in cases of severe acute respiratory infection (SARI) and a 5% increase in cases of influenza-like illness (ILI) were observed compared to the same period in 2024.
The early onset of H3N2 viral circulation will extend the transmission period. Photo:iStock
According to the statement, by week 45, influenza type A (H1N1) pdm09 predominated in the Caribbean and Central American countries. In North America, although the activity of this virus was at low levels, there was a sustained increase in influenza type A. In the United States and Canada, greater circulation of H3N2 was found, in addition to a progressive increase in the K subclade.
Cases of H3N2 variants in the region: Colombia is among the 5 countries with the highest figures
PAHO has monitored all H3N2 influenza variants in America until the current week (week 48). The data from this entity reports that the subregion most affected by this virus is North America, which throughout the year has presented 51,690 cases in all variants, and is the only region where the subclade K variant has reached, which has affected the United Kingdom and other countries in Europe. The country with the most cases is the United States, which registers a total of 32,868, followed by Canada with 14,613 and Mexico with 4,209, which on December 12 confirmed the first case of subclade K.
From the Ministry of Health of Mexico it was reported that the patient who contracted the virus responded to the antiviral medication treatment and is now recovered. The entity asked the population to attend health centers and other medical units to apply the vaccines that correspond to the winter season, especially the one that acts against influenza. In addition, he recommended receiving standard antiviral treatment, wearing masks and maintaining isolation measures, in case of testing positive.
The Ministry of Health, together with the National Epidemiological Surveillance System (SINAVE) of Mexico, will carry out permanent monitoring and analysis to detect cases of this virus in a timely manner.
In South America, although this subclade K virus has not yet arrived, there have been 10,156 cases of other H3N2 variants. Brazil rebounds with a figure of 6,563, followed by Colombia with 1,403, Chile with 1,389, Peru with 515 and Ecuador with 174. The rest of the countries register less than 100 cases, among them is Venezuela with 69, Argentina with 19, Paraguay and Bolivia with 4 and Uruguay with one.
In Central America, they had a total of 447. In this area, Honduras was the country where the most cases of H3N2 have been reported, with a total number of 178. Then, there are Guatemala with 124, Costa Rica with 104 and with a much smaller record, Panama with 32 cases, Nicaragua with 5 and El Salvador with 4.
The Caribbean region is where this variant has had the least presence, since, until week 48, the total number of cases is 235. In this group, all countries had fewer than 80 cases. With 72, Jamaica had the highest number, followed by Haiti with 64, the Dominican Republic with 20, Saint Vincent and the Grenadines with 18 and Guyana with 10. Suriname had 7 cases, Saint Lucia and Cuba 6 and Belize 3. Meanwhile, Dominica and Grenada, with 0 cases, are the only countries on the continent that H3N2 influenza has not reached.
They recommend vaccination against influenza. Photo:Ministry of Health.
Given the increase in this virus and the possibility of the H3N2 subclade K influenza variant arriving, PAHO recommends that countries adjust their preparation plans and organization of health services in the face of the possibility of an eventual overload in the health system. In addition, this entity, together with the World Health Organization (WHO), suggests strengthening surveillance of influenza, respiratory syncytial virus (RSV) and Covid-19 and adopting measures to prevent and control respiratory virus infections.
MARÍA PAULA AGUDELO CARRASQUILLA
SCHOOL OF MULTIMEDIA JOURNALISM EL TIEMPO
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