Covid: why they are comparing the omicron variant of the coronavirus with measles

el coronavirus no produce los mismos síntomas que el virus del sarampión. Pero la afirmación se refiere a su capacidad de contagio y no a los síntomas. Fotografía: BBC Mundo.

the coronavirus does not produce the same symptoms as the measles virus. But the statement refers to its contagiousness and not to the symptoms. Photography: BBC Mundo.

Obviously, the coronavirus does not produce the same symptoms as the measles virus. But the statement refers to its contagiousness and not to the symptoms. And in that sense, Alfredo is absolutely right.

The omicron variant caused a great stir from the first moment in which it was announced that it accumulated a large number of mutations that were essentially focused on the recognition zone between the virus protein S and the ACE2 protein of human cells.

Only that data and the fact that it had been sequenced already indicated that it was imposing itself on the other variants.

The initial political and media commotion did not respond to a greater severity in the symptoms but to its greater infectivity.

But, as has happened with other previous variants, when a new variant is detected it is because it is already circulating among the population.

For this reason, all the precautions of governments closing borders have been of no use. Now, in all countries, including Spain, the omicron variant is prevailing over previous variants including the delta.

It is this increased infectivity, as high as measles, which makes it more worrisome than the other variants.

London street.

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The high transmissibility of omicron, more contagious than other variants, draws parallels with the way measles is spread.

What is the infective capacity of the omicron variant?

To determine the dispersal capacity of a pathogenic organism, a parameter known as the basic number or basic reproduction rate (R₀) is applied.

It is nothing other than the average number of new cases that a positive case generates over a period of infection. For example, if a pathogen has an R₀ of 2, it means that an infected person will infect two others on average.

And that already causes the number of infected to increase exponentially.

The R₀ parameter is inherent in viruses, but it can vary according to conditions and is directly dependent on the number of contacts.

Highway in Barcelona, ​​Spain.

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The reproductive number of a virus marks the number of people that an infected person can infect. To reduce that number, at other times of the pandemic, total confinement of the population was necessary.

In cases of pandemic, it is essential to reduce the R₀ through confinement or quarantine measures to prevent an infected person from infecting others. Only in this way is R₀ reduced.

Thus, if the R₀ reaches a value below 1, the pathogen disappears over time. On the contrary, if it is higher, the contagion increases.

Among the most contagious pathogens we find the measles virus, which is transmitted by air and whose R₀ is between 12 and 18.

Below are whooping cough, with an R₀ of 12 to 17; diphtheria, 6 to 7; smallpox, polio, and rubella, with an R₀ of 5 to 7.

Interestingly, although they are very contagious pathogens, all of them have been controlled thanks to vaccines. For all of them, except for smallpox that has been eradicated, we have vaccines within the official schedule that are injected in the first years of life.

That is, despite their high contagion capacity, these pathogens no longer cause us diseases, except outbreaks that have occurred especially in unvaccinated groups, because they are being immunized since childhood.

Baby with skin rash on his face.

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The R₀ of the different variants of SARS-CoV-2 has increased as the virus has spread among humans.

A recently published study indicates that the R₀ of the initial variant that began to spread across the planet was 2.5.

For the delta variant, which was quickly imposed all over the world, an R₀ of around 7 is calculated and the new omicron variant that is already displacing the delta variant is being calculated an R₀ of 10.

To put this in context, the 1918 flu is assigned an R₀ between 1.4 and 2.3, lower than that of the coronavirus and much lower than the current variant.

To which we must add a situation of global mobility much more limited than the current one. Y There is the problem.

Similar infection mechanism, airways

Another important aspect is that both viruses, measles and coronavirus, use the same contagion route: the air.

Despite the first hesitations about its contagion mechanism, it is already clear that SARS-CoV-2 is transmitted mainly by aerosols. And that is also another important factor for its dispersion.

Although there are other viruses such as HIV (4.2 to 10.6), hepatitis C (2.1 to 3.9) and Ebola (1.2 to 1.9) that have R₀ worrisome, their transmission mechanism it is easily controllable.

But in the case of an airborne virus, with a high R₀ and with a long presymptomatic period, contacts are almost impossible to avoid.

Dance club in London this summer.

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The fact that many people can pass the coronavirus infection asymptomatically makes it difficult to control the infections.

To all this we must add the fact that many of the infected people suffer the infection asymptomatically.

The latest studies in Spain show that 30% of those infected have passed the infection asymptomatically or with symptoms so mild that they did not require special attention.

This makes the spread of the virus even more uncontrollable since many people may be contributing to the spread without realizing it.

New conditions, new solutions

Viruses evolve, especially if they have managed to infect a new host.

The initial conditions of the pandemic required drastic measures to avoid massive infections and the collapse of health systems. Without antivirals, without efficient therapies, without proven clinical protocols and without vaccines, we were all at the mercy of the virus.

Now the majority of the population is vaccinated with the complete regimen and their immune system contains memory cells prepared to detect and activate rapidly, even more so if its capacity is reinforced with a third dose.

Only a low percentage of people with poor immunity and the low percentage of unvaccinated people are in real danger.

The data in Spain show that unvaccinated people become at higher risk 20 times compared to those vaccinated for hospitalization, admission to the ICU or death.

Syringe over masks.

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Vaccines, like measles, have prevented many infections and deaths from coronavirus.

With this situation, the debate about the measures that should or should not be taken is very complex. A changing situation, a more contagious virus and a high percentage of the vaccinated population are important factors that affect decisions.

As is already partly done in the case of seasonal flu, the follow-up of symptomatic cases, the reinforcement of primary and emergency care and vaccination are the most appropriate sanitary measures.

Citizens can contribute by reducing contacts as much as possible and avoiding situations that favor the spread of the virus.

The only defense and way out of this pandemic is immunity and avoiding contact if infected. In this way we will reach the balance that already exists with the four human coronaviruses that cause colds and that once traveled the same path that the current SARS-CoV-2 is traveling.

Guillermo López Lluch is a member of the Spanish Society of Cell Biology, the Spanish Society of Biochemistry and Molecular Biology, the Spanish Society of Geriatrics and Gerontology, the Society for Free Radical Research and the International Coenzyme Q10 Association.

This article was originally published in The Conversation magazine. Click here to access the original article.

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