- The world is in the midst of a tripledemia due to the sum of Covid-19, influenza and RSV.
- It is thought that the Xibalbá Variant or BW.1 arose in July 2022 in the Yucatán Peninsula.
- It is a direct descendant of Omicron and is characterized by the fact that it is highly transmissible and can reinfect people.
According to the most recent report from the Ministry of Health (SSa), for six weeks there has been an increase in cases of Covid-19 in Mexico. The outlook does not look optimistic because it is combined with the arrival of the winter season and the celebration of the December holidays. Although unlike in the past now the Variant Xibalbá or BW.1 is the one that predominates in the national territory.
In this vein, the authorities’ forecast is that, unlike what has happened in the last couple of years, now the mortality rate will be quite low. It is all thanks to vaccination coverage because the majority of the population is protected against severe cases. Regarding infections, it will be different because growth is expected over the following weeks. In addition there are also other pathogens such as influenza and Respiratory Syncytial Virus (RSV) that are active and make up what has been described as a tripledemia.
Due to the above, one of the highest recommendations is to continue with basic prevention and hygiene measures. In fact, the government of Nuevo León had to rectify and return to the use of face masks in closed spaces.
Variant Xibalbá, first emerged in Mexico
However, according to a study carried out by specialists from the Institute of Biotechnology (IBt) of the UNAM, Rodrigo García López and Alejandro Sánchez Flores, the variant of the SARS-CoV-2 virus that today predominates in the southeast and central Mexico is BW.1, although it is popularly known as Xibalbá. It is believed that he emerged in July 2022 in the Yucatan Peninsula and is a descendant of Ómicron. Since then, it has spread to the United States and other regions of the world.
“The early identification of this new variant that is being seen in Mexico allows us, for the first time in the history of the pandemic, to have information that helps us apply effective measures to prevent and not only describe what happens in a wave (of contagions)”, emphasized Sánchez Flores.
In the Mexican Consortium for Genomic Surveillance, to which the IBt belongs, have monitored the cases in the Mexican Republic and it drew their attention that as of last October they increased considerably in the Yucatan Peninsula. As part of the surveillance, the genomes are sequenced in those samples positive for SARS-CoV-2.
“In reviewing we saw a large proportion of a variant that was identified as BW.1 that was genetically very similar to one that had been circulating in July of this year, which is BA 5.6.2, so we started doing an analysis. which mutations were different, and we detected that, like other variants that circulate more strongly not only in Mexico but in the world, they coincide with a series of mutations in the spike, which have an improvement for the virus in the capacity exhaust; that is, it is easier for them to reinfect people who already had a certain level of immunity,” explained García López.
The IBt researcher added that the BW.1’s appearance was in July 2022 during the fifth wave of COVID-19. Its accelerated growth can be explained, in part, by relevant escape mutations also found in BQ.1.
“Being an area with a very high capacity for tourism, not only has it remained in Mexico, but we have already detected it in Israel, the United States, France and even in Japan, probably from people who were tourists in the Mayan area,” explained García López. .
The scientists believe that in the center of the country the BW.1 variant will compete for a few weeks with the BQ.1 and its descendants, some of the most successful described to date that are currently concentrated in the north and center, and coincide with a new rise in cases towards the end of 2022. In the Yucatán peninsula, on the other hand, the BW.1 variant has had a months lead, which is why it will probably slow down the expansion of the BQ.1 lineage.
The rapid growth of the BW.1 variant coincides with a new increase in COVID-19 cases that occurred in southeastern Mexico in October 2022, ending a period of low transmission after the fifth epidemiological wave in Mexico.
People at higher risk
It is important to note that all currently circulating variants are descendants of Ómicron. They are characterized by causing a mild disease for the majority, but which continues to be a risk for the elderly and children, as well as for those with hypertension, diabetes or obesity.
Sánchez Flores added that the prevalence of the virus has a lot to do with what is happening in the world, because there is no sanitary fence in Mexico and, instead, there is free entry of tourists from other countries who arrive at a time when there is a wave caused by a certain variant. By importing it and taking it to a place where measures have been relaxed, the virus continues to accumulate mutations as it passes through Mexico, some of which may give it evolutionary advantages.
The existence of the variant is not reported directly to the World Health Organization (WHO) but with genomic surveillance, the National Institute of Epidemiological Diagnosis and Reference is notified, which in turn does so to the Ministry of Health, and they carry out the interface.
He recalled that the genomes that they obtain from sequencing these variants allow exploring the path followed by the pathogen that is seen, practically, in its evolution in real time, as had never been done before before the pandemic.
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