The omicron variant of covid-19 arrived in Latin America at the end of November, and by the end of December it had already become the dominant strain in the world. The curves of detected cases then became vertical, as had already happened in South Africa or the United Kingdom. Omicron’s central question for the region, as for the entire world, was whether these cases would translate into saturation of the health system and, eventually, deaths, as had already happened with previous peaks, especially those dominated by the delta variant. The first consolidated data on hospitalizations help answer it: for now, the aggregate severity is notably lower, at least in Argentina, Mexico and Colombia.
Argentina was one of the first countries to detect a never-before-seen growth in detected cases. It helps that their testing system is relatively streamlined, with quick results based on antigen tests. At the end of December, it had already far exceeded its previous daily record of 40,000 cases, even tripling it. Today, the two-week cumulative incidence triples that of the peak in late May and early June 2021. But hospitalizations in intensive care are barely a quarter of those then.
As in Argentina the curves of cases and hospital admissions begin to show signs of stabilization (still to be confirmed in the trend of the next few days, certainly: in 2021 there were unexpected spikes caused by new outbreaks in specific regions), it is already possible to affirm that, For now, a much higher number of cases than the country has experienced so far has produced far fewer hospitalizations.
The same trend, in similar magnitudes, is observed in Mexico. Detection is notably worse than Argentina: fewer tests per confirmed case, and inconsistencies in the data between peaks. The one with the most deaths and intubations was at the end of 2020, but the cases peaked in 2021, when detection improved significantly without becoming perfect. In exchange, the disaggregated database offered by the Mexican Ministry of Health allows working with daily admissions of positive and suspected cases both in the ICU and in intubation, distinguishing between the two. Counting those from the last 14 days, and comparing them with the same aggregation of confirmed cases, it turns out that although the latter multiply by 1.6 those from the middle of last year, only one eighth of those from then have ended up with mechanical ventilation.
These data are consistent with what was observed in both the UK and South Africa. In the first, estimates from the public health system risk analysis service (UKHSA) suggest that the complete vaccine schedule reduces the risk of hospitalization by between 50% and 70%, depending on the time that makes the person received it. That is to say: the original risk of each individual, at least, of ending up in the hospital would be divided by two. This is multiplied with a reinforcement: close to 90% reduction, or what is the same, an ability to divide the original risk by ten. The effect of immunity produced by a past infection was also studied in the United Kingdom: between a 40% and 60% reduction in the risk of hospitalization. That is to say: another division by two of the original risk.
In both countries, in addition, the extent to which omicron was an intrinsically less severe variant was analyzed regardless of acquired immunity: again, between a 40% and 66% reduction in the chances of entering hospital. Data from France, where the omicron spike is being particularly intense in cases, also indicates shorter hospital stays. Finally, a preliminary study focused on the worst possible outcomes prior to eventual death finds even greater reductions: 67% less in ICUs, 84% less with mechanical ventilation.
This improvement in the most serious versions of covid is reproduced not only in Mexico and Argentina, but also in Colombia, where the data allows us to distinguish between non-critical and critical hospitalizations, drawing the same double gap that can be seen in Mexico between ICUs and intubations.
Given that the Colombian government has recently modified its requirements and conditions for diagnostic tests, relaxing them, it is possible that the number of cases detected over the real total in the country will decrease in this wave compared to the previous ones. This would make it difficult to compare severity, but it would not affect the general hospitalization and ICU curves, since these more serious cases continue to receive confirmation in the same way as before. This allows us to conclude that ómicron hospitalizations are, for now and in this country, less serious.
In light of the current data, in these Latin American countries the three factors (immunity due to vaccines, due to past infection -particularly frequent in Colombia or Mexico, for example- and less intrinsic severity of omicron) would be combining to convert the covid in a disease with a remarkably less impact than it had until now on health systems. Immunity from past infection may prove particularly beneficial in a region that has seen the highest infection rates in the world, but it has done so at a hefty price: Latin America is also home to some of the countries with the highest accumulation of deaths during the pandemic. .
While waiting for more and better data to confirm this evolution, there is a caution and two uncertainties to take into account. Caution comes from measuring the size that covid can continue to have. Even if this disease becomes an equivalent to seasonal flu, it causes between 290,000 and 650,000 deaths annually in the world according to the latest comprehensive estimate from the WHO. Even in this scenario, notably more positive than the one the pandemic has accustomed us to, we would be adding thousands of deaths annually to the regional catalog of those caused by respiratory disease.
The uncertainties come from the fact that this scenario, or others, are not yet certain. The transition from pandemic (unpredictable) to endemic (predictable) is not consolidated because neither the stability in the SARS-CoV-2 mutation process nor the stability over time of acquired immunity against severe disease has yet been confirmed. . This, moreover, continues to be remarkably unequal by age or comorbidities, but also by territory: there are broad layers of the Latin American population that continue to be exposed to the impact of covid, although others are increasingly protected. The penetration graph of the current vaccines in their different regimens (single dose, two doses, booster) makes these gaps clear.
The work now of both science and politics will consist of dimensioning the risks and their distribution (who is affected more, who is affected less) in order to be as efficient and equitable as possible in the unavoidable task of minimizing them in the long term.
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