Can you know what percentage of the world population had COVID-19?

Despite the fact that the testing criteria are dissimilar in the world, the prestigious scientist Eric Topol analyzed a series of works published in recent weeks and warned that the majority of children and adults under 60 years of age had evidence of contact with the virus.

At this point in the pandemic, experts estimate that more people have had COVID-19 than have managed to avoid infection. And although this number of individuals is small, it is an outstanding debt for scientists to know how they managed to avoid SARS-CoV-2. However, far from focusing on those who evaded the virus, in recent weeks they have focused on finding out how many and who have contracted the disease, and how this situation impacts global public health.

Beyond the fact that in many countries the testing regime declined and in others diagnoses put aside genomic surveillance, the prestigious scientist Eric Topol, founder and director of the Scripps Research Translational Institute, announced, through his Twitter account, three reports released in recent weeks. These works, with different methods, population and study time, indicated that between 42 and 94% of the world population had COVID-19.

The first of the documents shared by the professor of molecular medicine and executive vice president of Scripps Research in the United States, belongs to the Centers for Disease Control and Prevention (CDC) and ensures that “a high percentage of American adults have antibodies to SARS-CoV-2, obtained through vaccination, infection, or both.

Specifically, they state that “during August 2021 to May 2022, 41.6% of a convenience sample of adults had both spike antibodies (indicating prior infection or vaccination) and nucleocapsid antibodies (indicating only a previous infection). Meanwhile, “43.7% of these people were possibly asymptomatically infected. The prevalence of serologic patterns consistent with vaccination without infection was lower among younger adults, Hispanic and non-Hispanic black or African American adults, and people with less education.”

For its part, the medRxiv site, which brings together specialized science and health publications, published a preprint that has not yet been peer-reviewed entitled “Changes in the population’s immunity against infection and severe disease due to the Omicron variants of SARS-CoV -2 in the United States between December 2021 and November 2022.”

In the article, the researchers highlight that “although a substantial fraction of the US population became infected with SARS-CoV-2 between December 2021 and February 2022, the subsequent evolution of population immunity against the variants The Omicron test for SARS-CoV-2 reflects the competing influences of waning protection over time and the acquisition or restoration of immunity through additional infections and vaccinations.”

As they saw, by November 9 of this year, 94% of the US population had been infected by SARS-CoV-2 at least once. Combined with vaccination, it was estimated that 97% had some prior immunological exposure to SARS-CoV-2. Between December 1, 2021 and November 9, 2022, protection against a new Omicron infection increased from 22% to 63% (51%-75%) in the North American territory, and protection against an Omicron infection that led to serious illness increased from 61 to 89%.

Meanwhile, a Canadian Medical Association Journal publication reported that by August 2022, the majority of children and adults under the age of 60 had evidence of both vaccination and SARS-CoV-2 infection. “As previous evidence suggests that a history of both exposures may induce stronger and longer lasting hybrid immunity than either exposure alone, older adults, who have the lowest infection rates but the highest risk of severe outcomes, continue to justifying priority vaccination,” the researchers noted.

Asked what the implications of the findings are for public health practice, the CDC recommends that everyone stay up-to-date with COVID-19 vaccination. “These results may guide the ongoing efforts needed to achieve equity in primary series vaccination and booster dose coverage,” they said.

A few weeks ago, Topol had expressed interest in the development of nasal vaccines as reinforcement for the future, as one of the keys for the world to free itself from the pandemic. “I have not lost hope that they will promote nasal booster vaccinations as a way to restore a high level of protection against infections, and better, longer-lasting and variant-proof vaccines,” he had written in his weekly newsletter.