First official data: ómicron prevailed over delta and has predominated for four weeks in the country
From one week to another, in the last two weeks of last year, omicron turned the variant more prevalent since then in this wave of infections driven until then in the country by the local circulation of delta. In those 15 days, according to a new official report on surveillance of the circulation of the Covid-19 virus, the new strain reversed the trend: cases by omicron they increased “abruptly” from 27.7% to 84.4% and thus continued in the first week of this year.
The data, which arises from the work of the teams of Anlis Malbran and the PAIS consortium, update the information on the behavior of the variants of the new coronavirus until the first week of this year inclusive. An x-ray that traced THE NATION Based on the results reported in the 16 previous official reports, it had been possible to clearly describe how delta advanced along with the election campaign of 2021, without being made public, until coinciding with the abrupt rebound in infections of this new wave.
The new document now adds to the previous ones and describes how omicron displaced delta, according to samples of positive cases analyzed.
“The circulation of the variants of SARS-CoV-2 is currently characterized by rapid growth in the omicron variant with a concomitant decrease in the detection of delta variant in several of the jurisdictions of the country”, is indicated in the report, which incorporates information from the analysis of 3337 samples of positive cases of Travellers and people no recent travel history, obtained between December 20 and 10 of this month, with data provided by eight jurisdictions (the city of Buenos Aires and the provinces of Buenos Aires, Córdoba, La Pampa, Salta, Mendoza, San Luis and Santa Fe) for omicron and 12 districts for delta (the city of Buenos Aires and the provinces of Buenos Aires, Córdoba, Santa Fe, Mendoza, San Luis, Tucumán, Santiago del Estero, Salta, Jujuy, La Pampa and Sant Cruz).
In the first week of 2022, according to the new data, the proportion of the omicron variant in the positives without a history of travel abroad or related to a traveler (close contact) was 84.4% while the delta fell to 15.6%, according to the results by genome sequencing Y PCR-RT that were uploaded to the national epidemiological surveillance system.
In mid-December, 92% of the case studies they corresponded to the delta variant. For Christmas, that proportion had decreased to 72.3% and omicron was already beginning to rebound, which for the same interval had grown from 7.9% to 27.7% of the cases, along with their movement around the country.
For New Year, contagions by delta represented 18%, while omicron was installed as the most prevalent variant with 82% of the samples studied. A week later, these proportions were, respectively, 15.6% and 84.4%.
“The detection of the concern variant gamma (P.1) continues to represent less than 1% of the samples studied. With respect to alpha (B.1.1.7) no cases have been recorded since epidemiological week 42 [tercera semana de octubre]. In relation to the variant of interest lambda (C.37), also corresponds to less than 1% of the cases registered in recent weeks,” the report specified.
Three weeks ago, before the Ministry of Health of the Nation release this new genomic surveillance report, the Argentine consortium PAIS published its first data on the samples analyzed in the network of laboratories that comprise it.
“At this moment –the consortium anticipated–, Argentina is going through a third wave, which, according to our results, was initially associated with the delta variant and, more recently, with the entry and propagation of omicron. This new wave of infections It is probably due to multifactorial causes that include from the relaxation of care measures in the population, increase in social gatherings at the end of the year and higher income of individuals from abroad, to intrinsic characteristics of higher transmissibility and likely evasion of immune response of the omicron variant.”