what possibility of being infected has the one who already had Covid

Argentina adds almost 5.3 million of infected registered Covid. The infected curve in recent months touched its bottom two weeks ago. Since then it has risen again, hand in hand with the greater circulation of the Delta variant, while the 55 percent of the population is vaccinated with two doses.

While the third wave of Covid is being assembled in the country, the question arises: what possibility of reinfection do they have those who already had the disease. Until the end of 2020, the global rate of reinfections was less than 1 percent, more precisely than 0,65. However, with the Delta the scenario would seem to change, although not much.

Clarion It revealed the information available in some countries that have gone through the third wave or are in that trance, with the experience of community circulation of the variant that emerged in India. From there they come off some hints.

Part of the data comes from Spain. There it has been confirmed that the 0.7 percent of the third wave cases have allegedly been reinfections. That is, less than one in every hundred new infections.

According to official information, Spain had between May and September 1.3 million new Covid cases. Of this total, it is estimated that there were 9,082 cases that could be reinfections. Although only the 8 percent of that total was confirmed reliably.

A Covid infection under the microscope. Photo: AFP

The rest are “possible or probable reinfections”. It is because it is not known if, in fact, it is the same infection that has never finished leaving the body or a new one. To corroborate this, a genomic study of the virus must be carried out. According to the evidence, this study has been completed and tested positive in 0.05 of the reinfections.

The Committee on Covid-19 of the Illustrious College of Physicians of Madrid has, however, in its recent report, a margin of uncertainty: Although it states that reinfection in general is usually asymptomatic and benign, it also says that it can behave like the first infection and be even fatal.

The third wave has on one side the Delta variant as possible enhancer of reinfections, on the other the vaccination as counterweight. Adding to the risk of Delta would be cushioned by active immunization. That could leave the eventual percentage of reinfections at a similar level.

Research published in The Lancet Microbe by Jeffrey Townsend, professor of biostatistics at Yale University, asserted that reinfections can occur “In three months or less”. His aim was to explain that natural immunity is short-lived and that these people they should be vaccinated anyway.

The data further suggest that as time passes the probability of reinfection goes up due to the combination of two factors: immunity decreases and the chance of new variants increases. The data indicate that the risk of reinfection increased 5 percent four months after the initial infection and 50 percent, at 17 months.

A nurse prepares a dose of vaccine in Technopolis.  Photo: AP

A nurse prepares a dose of vaccine in Technopolis. Photo: AP

What about Britain, where the case curve has skyrocketed in recent weeks? Reports indicate that most of those infected there are people who they have not been vaccinated, both boys and adults. In addition, a strong impact of vaccination has been seen, at least for now, in the lethality control.

A new analysis from the UK’s Office for National Statistics indicated that the reinfection rate “Is still low”. Agency analyst Kara Steel said “it is encouraging to see that when reinfections do occur, they are generally less likely to cause serious illness.”

Jorge Quarleri, biochemist at the University of Buenos Aires and principal investigator at Conicet, explained to Clarion: “The issue of ‘reinfections’ is still somewhat unclear because in its analysis there are multiple variables that influence and, as the epidemiological scenario changes, the dynamism it also makes what seemed clear to move ”.

He added: “Undoubtedly the possibility of reinfection goes hand in hand with the ‘durability over time’ of an effective immune response. That aspect can be related to ‘one of the protagonists’, that is to say the host. On the other hand you have to consider the behaviour of the virus (the other protagonist), which we already know is dynamic and restless ”.

Quarleri considered that “the generation of variants with different capacities to evade the established immune response could endow it with a greater ability to reinfect. Delta, as a variant, exhibits a differential capacity with respect to its precursors, which allowed it to displace them and ‘reign’ in the epidemiology of infections in recent months, in a wide spectrum of countries. However, his hardest blows have been -mainly- in unvaccinated people with no previous history of infection”.

Jorge Quarleri, biochemist and researcher at Conicet.

Jorge Quarleri, biochemist and researcher at Conicet.

The relationship between infections, vaccination and deaths is reflected in the statistics. In the last week the fatality in the United Kingdom has been 0.27 percent. In the United States, where the resistance of many citizens to being vaccinated plays against, the fatality of the last seven days has been of the 1.97 percent. In France, from 0.57 percent; in Spain, from 1.43 percent; in Chile, from 0.56 percent; in Israel, from 0.79 percent.

Although the number of deaths in Argentina has been declining sharply in recent months, the fatality rate for the past week has been 2.16 percent. However, the gap between cases and deaths must be considered, since the latter are usually reflected approximately one month after the infection is declared.

In sum, it can be asserted that vaccination in the world has given signs of success despite the circulation of the Delta. The historical lethality of the Covid to date is of the 2.03 percent, while the lethality reflected in the last seven days has been of the 1.60 percent.

According to a recent report from the US Centers for Disease Control and Prevention, people recovered from Covid vaccinated subsequently have half the risk of reinfection compared to unvaccinated people who had Covid.

All of which speak of a present scenario More optimistic than last summer, provided that vaccination continues to advance to cover the entire population and preventive health care is sustained. At least until what are signs today are consolidated as certainties. And the uncertainty of the pandemic gives rise to an endemic of more predictable features.