The speed with which BA.5 subvariants by Ömicron has grown up in Argentina is amazing. On June 29, it was registered for the first time. Now, in the latest genomic surveillance report from the Ministry of Health on the Covid-19he realizes that he already represents the 53.5 percent of the detected cases.
The growth has been exponential, as has been happening with the volume of circulation of the virus since the beginning of the pandemic. In fact, the great explosion of cases of these subvariants occurred in the last three weeks, a period in which they went from being below two digits to more than half of the total.
“The high transmission pattern observed for Ómicron has facilitated the appearance of additional mutations that define different sublineages classified within the same variant. To date, 5 different main Omicron lineages have been reported globally: BA.1, BA.2, BA.3, BA.4 and BA.5 and their descendant lineages (BA.1.1, BA.2.12.1, among others). others),” the report says.
The report for week 30, prepared by the Ministry of Health, adds that BA.2 now represents only 2.61 percent of the total cases, while BA.2.12.1 means 4.51 percent. BA.4 represents 10.57 percent and BA.5, 53.59 percent. Between the two most contagious in the country, they add up to 64 percent.
We all see how the cases in Argentina grow week by week through the Sunday reports, along with the incessant multiplication of BA.5. With the exception that the recorded infections represent a small part of the real cases.
Swab analysis in Mendoza. Photo: The Andes
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The infectologist Roberto Debbag has already said in this medium that the official figure that is being disseminated should be multiplied today “for 15 or 20” to have a true dimension of contagion. This is because there are few tests and the variant becomes increasingly contagious. However, the tip of the iceberg marks a trend.
The number of cases in the last part was 52,745, which represented 26 percent more than the previous week. This Sunday the new weekly figure will be known in order to continue evaluating the curve speed.
The subvariants of Ómicron BA.4 and BA.5 have the mutation that could give them greater transmissibility and characteristics of immune escapeboth to vaccines and to antibodies created by a previous infection.
The official report indicates that “preliminary analyzes carried out in the United Kingdom did not find a significant difference in terms of vaccination history in those infected with BA.4 and BA.5 compared to BA.2, which could suggest comparable vaccine protection to that previously evaluated. However, studies with an adequate design are required to evaluate the effectiveness of vaccines against these lineages”.
In the last three weeks of the analyzed period, lineages BA.4 and BA.5 are on the riseCovid-19 cases had already registered an increase of 9 percent between weeks 26 and 25 and 17 percent between 27 and 26. That weekly increase is, percentage-wise, growing. In addition, the number of deaths also registers an increase, although in a much lower proportion and absolute cases than in previous waves.
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The information available on the characteristics and consequences of these two subvariants is scarce and temporary. Among the most outstanding investigations -not yet reviewed by peers- two can be mentioned, which at first seem to be contradictory, but in reality they are not.
The first investigation, led by a researcher at the Washington School of Medicine, Ziyad Al-Aly, warns that with each reinfection the risk of presenting more severe symptoms is older. The assertion in principle would refute the belief that becoming infected generates greater immunity and the promise that next time the illness will be milder.
However, another investigation carried out at Weill Cornell Medicine in Doha, Qatar, indicates that the previous contagion with Ómicron protects against subvariants BA.4 and BA.5, with a coverage of 76 and 79 percent respectively. The conclusion, when weighing both works, would indicate that although getting infected twice with Ómicron is more difficult, the one that actually gets infected could have more severe symptoms.
Omicron’s offspring in the world, meanwhile, does not stop. When BA.5 was believed to be the most contagious subvariant, another appeared: the BA.2.75 lineage, better known as Centaurus and originally from India. It has 45 mutations in common with BA.5 and 15 of its own.
The consolation -no less- is that the power of vaccination is making the virulence of the infection more limited than with previous variants. In any case, if the curve of cases grows a lot, it could have repercussions due to a mathematical question -as has happened in other countries- in the demand for hospitalizations.
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