Another common cold virus?

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What is the end of SARS-CoV-2, the virus that causes covid-19? As millions of people are vaccinated against the coronavirus, and the end of the pandemic finally seems to be looming, the Scientists are beginning to imagine what a post-vaccine world would be like, and what they see is comforting.

The coronavirus is here to stay, but once the majority of adults are immune, after a natural infection or vaccination, the virus will be no more of a threat than the common cold, according to a study published yesterday in the journal. «Science».

In this article, based on a model developed by scientists from the Emory University and of Penn State (USA) which has reviewed studies of the four common cold coronaviruses and SARS-CoV-1, it is stated thate, if it becomes endemic and circulates in the general population, and most people are exposed during childhood, SARS-CoV-2 may join the group of mild coronaviruses that cause colds and that currently circulate during the colder seasons of the year.

The virus is a threat because it is an unknown pathogen that can overwhelm the adult immune system, which has not been trained to fight it. But that will no longer be the case once we have all been exposed to the virus or the vaccine.

«All four common cold coronaviruses are endemic and produce only mild symptoms

Children, on the other hand, are constantly exposed to new pathogens, And that is one of the reasons why they are more adept than adults in defending themselves against the coronavirus.

Over time, the study suggests, the virus will be a cause for concern only in children younger than 5 years old, subjecting them to even simple colds, or no symptoms at all. In other words, the coronavirus will become “endemic”, that is, it will be a pathogen that circulates at low levels and rarely causes serious disease.

“The time it takes to reach this type of endemic state depends on how quickly the disease spreads and with which vaccination is implemented,” he says. Jennie Lavine, first author of the article. So, he highlights, “the challenge is to expose as many people as possible to the vaccine for the first time as quickly as possible.”

“The challenge is to expose as many people as possible to the vaccine for the first time as quickly as possible”

Lavine explains, that the four common cold-causing coronaviruses have been circulating among us for a long time and almost everyone has been infected at a young age. Natural infection during childhood provides immunity that protects against serious disease in the future, but does not prevent periodic reinfection. ‘All four common cold coronaviruses are endemic and only produce mild symptoms.

SARS and MERS, which emerged in 2003 and 2012, respectively, made people seriously ill, but did not spread widely, ”they write in their work.

According to the researchers, in the case of these viruses, the term “herd immunity” is incomplete and possibly misleading.

“A reinfection may occur within a year, but even if it does, the symptoms will be mild and the virus will clear from the body more quickly,” Lavine says.

The researcher affirms that one must understand the different types of immunity. In other words, «how long does the immunity that prevents the disease last and how long does the immunity that prevents transmission last? They can be very different.

Although there are now studies that provide concrete data on the duration of immunity with antibodies and immune cells against SARS-CoV-2 after infection, however, researchers are still determining how these components translate into protection against disease or transmission.

«How long does the immunity that prevents the pathology last and how long does the immunity that prevents transmission last? They can be very different »

“We often wonder how SARS-CoV-2 compares with other viruses such as seasonal flu or respiratory syncytial virus. Our model assumes that immunity to SARS-CoV-2 works in a similar way to other human coronaviruses “, says this expert who, however, recognizes that it is not really known what it would be like if someone contracted one of the other coronaviruses for the first time as adult.

The model predicts that the case fatality rate from SARS-CoV-2 infection it can drop below that of seasonal influenza (0.1 percent), once endemic stable status is reached.

“We are in uncharted territory, but a key message from the study is that immunological indicators suggest that mortality rates and large-scale vaccination may decrease in the short term, so every effort must be made to resist this pandemic to obtain endemicity ”, highlights the researcher Ottar Bjornstad.

The model predicts that the fatality rate from SARS-CoV-2 infection may fall below that of seasonal influenza (0.1 percent), once an endemic stable state is reached.

A safe and effective vaccine against covid-19 could save hundreds of thousands of lives in the first two yearsBut continued mass vaccination could be less critical once SARS-CoV-2 becomes endemic, say the authors. “Targeted vaccination in vulnerable subpopulations can still save lives.”

Another implication is that during the transition to endemicity, it will be more difficult use symptoms only as a surveillance tool to look for infections and slow the spread of the virus. Thus, widely available evidence may become particularly important during vaccine launch to protect vulnerable populations, the authors note.

So far, the available data on SARS-CoV-2 in infants and young children suggest infection is mild and mortality lowAlthough there are exceptions at the individual level, and some experience rare complications such as MIS-C (multi-system inflammatory syndrome in children).

Conversely, if childhood SARS-CoV-2 infection became more severe, such as MERS-CoV (Middle East respiratory syndrome-related coronavirus), routine vaccination programs would still be necessary. authors.

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