In Argentina, tests fell by 65%: can the lack of detection of Ómicron BA.2 generate a new wave?

When at the end of last January, the wave of the coronavirus variant Ómicron BA.1 was receding, the first cases with another subvariant were already detected. It is the Ómicron BA.2 that generated spikes in COVID-19 cases in Asia, Europe and now in North America. Today, in Argentina, only the BA.2 subvariant is found in less than 1% of the samples of patients with COVID-19, according to the April report of the ANLIS/Malbrán Institute. There are 57 patients diagnosed with BA.2 However, as tests have dropped 65% since the first week of March and have now been restricted to prioritized groups, there is the the possibility that the increased circulation of that subvariant would not be recorded by the monitoring system.

According to ANLIS/Malbrán, the situation of SARS-CoV-2 coronavirus variants is currently characterized by an exclusive circulation of the Ómicron variant. That is, today only Ómicron circulates. Gone are variants such as Gamma, which predominated between March and August last year, and Delta, which was the main one between September and December last. Now, according to genomic surveillance analyses, Ómicron BA.1 predominates, and there is very little BA.2 at least in the samples of patients who arrive at the institute that is under the Ministry of Health of the Nation.

In the first week of March 2022, “the proportion of the Ómicron variant in cases without a history of international travel or import-related stands at 100%, implying that the proportion of Delta variant continued to decline” throughout the country, among the samples analyzed by genomic sequencing carried out by researchers of the Anlis/Malbran. “As for the Ómicron variant sublineages, BA.1 and BA.1.1 are fundamentally identified while BA.2 represents less than 0.5% of the sequenced samples,” they clarified in the report.

From January 2021 to April 3, researchers analyzed 24,395 samples for the identification of variants of which 14442 were studied by genomic sequencing and 9953 were detected by RT-PCR (screening). The samples include confirmed cases of COVID-19 selected for regular surveillance of circulating variants in the general population, or because they are serious, unusual conditions, people vaccinated, suspected cases of re-infection and travelers.

The first case of a person in Argentina with Ómicron's BA.2 sublinage was that of a 62-year-old man with COVID-19 residing in the city of Buenos Aires. The man had returned on January 12 from Uruguay and two days later he began to present symptoms compatible with the disease.

In the latest report that reaches April 3, it was reported that there are 57 people who were diagnosed with COVID-19 and who had the BA.2 sublineage. Of that total, 42 reside in Buenos Aires City, and 14 of them had travel history.

The rest were related to travelers or were being investigated. Meanwhile, 10 other patients out of 57 diagnosed with BA.2 were from the province of Buenos Aires, three from Santa Fe, one from Santa Fe and another from Tucumán. Last Monday, the Minister of Health of Córdoba, Diego Cardozo, reported that the first cases of patients with Ómicron BA.2 had been detected in that jurisdiction.

Beyond the reports, there is a possibility that there are more cases of COVID-19 with the subvariant but that they are not being reported or analyzed. Consulted by Infobae, Mariana Viegas, a researcher in virology at Conicet at the Ricardo Gutiérrez Children's Hospital in Buenos Aires and coordinator of the Country Project, the consortium for genomic surveillance of the coronavirus of the Ministry of Science, Technology and Innovation, commented: “In the few cases we are analyzing week by week, Ómicron BA.2 is detected between 25% and 50% of the samples. This is the rank for the low number of cases that are sent to sequence and the confidence interval gives wide”.

Weeks ago, the director of the Pan American Health Organization, Carissa Etienne, had warned that some countries had changed their strategies on COVID-19 testing. The reduction in the number of tests makes it more difficult to get the full picture of the variants in the region. For this reason, Dr. Etienne called for continued testing and to avoid “entering the next wave blindly.”

While cases and deaths from COVID-19 have declined in most countries in the Americas in recent weeks, the risk of further upturns cannot be ignored as restrictions are relaxed. Etienne recalled that “time and again, we have seen how the dynamics of infection in Europe are reflected here, just a few weeks later.” By the first week of April, the Ómicron BA.2 variant has already been detected in 8.7% of the sequences reported from South America.

In Argentina, tests for COVID-19 had broken records in the first weeks of January with more than 1.1 million per week considering the entire pandemic. Then, they were reduced. During the first week of March, 241,029 tests were carried out in the country, according to the analysis of doctor of physics Jorge Aliaga, based on open data from the Ministry of Health of the Nation. In the second week of April, only 85,087 tests were carried out. That is, there was a 65% decrease in the number of tests performed to diagnose coronavirus infection.

“The number of tests alone does not indicate whether the COVID-19 curve is rising or falling. Positivity - that is, cases diagnosed with infection - also needs to be considered in relation to testing. If tests go down and positivity is reduced or maintained, there are fewer cases. If there are fewer tests and positivity rises, there are no fewer cases,” Aliaga said today. In the province of Buenos Aires, tests fell and positivity continued to fall. On the other hand, in the city of Buenos Aires, tests fell, but positivity increased if the date of onset of symptoms of each person diagnosed is taken into account.

From now on, it will be more difficult to follow the minute by minute of the coronavirus and its subvariants in Argentina. Not everyone with symptoms will be tested. By consensus with the Federal Health Council (COFESA), the national portfolio led by Carla Vizzotti announced that the diagnosis of COVID-19 will be prioritized in people over 50 years of age and at risk; special populations residing, working or attending prisons, health institutions, centers with people institutionalized, and persons who work or care for vulnerable persons.

Testing can also be done on people with a history of travel in the last 14 days to a region in which a variant of interest or concern is circulating that is not circulating in the country; people with serious illness (hospitalized), or deaths and unusual cases; and on the occasion of investigation and control of outbreaks.

What could happen in the next few weeks? “The Ómicron BA.2 sublineage may increase its circulation in Argentina, but it would not have a serious impact as other variants have done before,” Roberto Debbag, president of the Latin American Society of Pediatric Infectious Diseases, told Infobae. “At this time, Argentina should continue to increase genomic surveillance and implement vaccination strategies against COVID-19 for specific groups, such as immunocompromised.”

The expert also considered that more communication campaigns should be carried out to ensure that people return to medical checks and that vaccination for children and adults is accessed for other diseases because coverage fell in the context of the pandemic. The decline in immunization coverage “may lead to the resurgence of diseases such as infection with Haemophilus influenzae bacteria,” Debbag said.

“Now it is almost impossible how much coronavirus is circulating in Argentina because the changes in the criteria for testing lead to fewer people going to do them. The situation was made even worse by the flu outbreak, as everyone assumes it's not COVID. To remedy this, surveillance data for the coronavirus in the sewage system could be improved and made public and it is necessary to promote that the general population that has not done so until now will apply the first booster dose and the prioritized groups apply the second reinforcement,” said Dr. Rodrigo Quiroga, researcher in bioinformatics at Conicet and the National University of Córdoba.

As of last week, 82% of the Argentine population had the complete primary dose schedule. But there was still 30.8% of the population that had not gone to receive the first booster dose. As reported to Infobae by the Undersecretary for Health Strategies of the Ministry of Health of the Nation, Juan Manuel Castelli, until Wednesday of last week the first booster dose had been applied in 16,754,328 persons in the country. There are 13,997,424 people who should be immunized as soon as possible with the booster dose because it has been more than 120 days since they received the initial schedule.

KEEP READING: