​Bogotá DC, December 2, 2021. The appearance of Omicron, the new COVID-19 variant, has put health authorities around the world on alert, mainly after the World Health Organization declared it of interest and concern. Colombia, for its part, is already conducting active surveillance and invites citizens to remain calm but following the known measures.

In this regard, the director of Epidemiology and Demography, Julián Fernández, pointed out that "it must be taken into account that all viruses change even starting from the moment of their appearance, which is constant and with a number of mutations from time to time, but it rises when there is a significant number of infected people."

In the specific case of Sars-CoV-2, what is observed, thanks to genomic surveillance studies, is that there are variants of the original Wuhan virus that have presented certain mutations and have taken on different characteristics. Some of these genetic changes are translated to a different epidemiological behavior.

"For example, it is known that the mutations of the spike, which is key in virus transmission, may be related to contagion capacity," explained Fernández, adding that this has to do with the probability that close contact may create a positive case; and also referring to the capacities that allow the virus to pass from person to person.

It is thanks to genomic surveillance at the international level that this new variant was identified in South Africa, but Fernández clarified that Omicron did not necessarily arise in that country.

The WHO subsequently determined whether the changes identified in the new variant could affect the transmissibility of the virus, if it had the ability to cause more severe disease or affect the ability of vaccines or treatments. "When one of these assumptions is considered plausible is when the WHO decides to declare it as of concern," he explained.

Surveillance strategy

Colombia has a genomic strategy with smart sampling that is performed in certain risk groups. It identifies unusual increases, takes into account travelers, among other groups, to conduct genomic sequencing to identify variants.

"Additionally, the National Institute of Health (INS) carries out a probabilistic study that allows estimating the proportion of cases corresponding to each variable and describing the prevalence of a particular variant over time. This allows us to observe that the predominant variant in 2021 in Colombia was Mu, which was progressively replaced by the Delta variant," said Fernández.

It is a combination of surveillance strategies, which also includes genomics, aimed at public health events and probability sampling. These are the responsibility of the INS, with the support of the Public Health Laboratory Network.

Measures

Although some countries have taken drastic measures in relation to Omicron, it should be borne in mind that Colombia is in an epidemiological moment that is different from that experienced in 2020. "Last year we had very little information on the behavior of the new variants at an epidemiological level; secondly, we did not have vaccines; and thirdly, we did not have data on the effectiveness of many of the measures," explained Fernández.

Today it is known that the closure of borders is not an effective measure to prevent the spread of new variants within a country, as explained by the director. "It is a measure that is not effective, but it is also not sustainable over time, and has great social impacts," he added.

In the particular case of Omicron, it is important to take the place where the variant was identified and where it originated into account. This means that just because it has been identified in South Africa does not mean that it is the country of origin.

Therefore, it is likely that other countries in Africa have a similar or even greater spread of Omicron, but simply do not have the capabilities to detect it.

For now, more than 25 countries in the world have confirmed the presence of the new variant, mostly imported. "And it is very likely that in at least the United States and Germany, there is already community transmission, surely so in many more countries," said the official.

With such a scenario, in a few weeks, Omicron would be widely present in most of the world, which makes it rather incoherent to close flights from a particular country.

"In addition, it is a measure that can be considered discriminatory and can discourage countries from reporting cases, because it is like punishing surveillance, while also producing extensive social and economic costs," said the director.

Vaccination

Given the situation, this is the much more critical time to start vaccination or reinforcements, in addition to strengthening self-care measures such as the use of a mask and hand washing.

"We have a group of people who have not yet received a single dose. These citizens, regardless of their age (over 3 years) must go to the vaccination points as soon as possible," the official requested.

Secondly, for the new variant, people already vaccinated must complete their schedules. "There is solid evidence that protection is greater with the full schedule than with a single dose," he said.

Lastly, there is the booster, mainly for risk groups, who can get their shot four months after the second dose, in the case of people 50 years of age and over. "It has been shown that boosters, particularly heterologous, provide greater protection since they stimulate the immune system," he recalled.

For this reason, given the possibility that Omicron is more transmissible, it is necessary to be vaccinated, but also to continue using the mask, with special emphasis on closed spaces. In addition, ventilate the spaces, and equally important, that the suspected or confirmed cases be isolated.

"If we realize it, these are actions that the public can take and that are what we have already been carrying out to combat COVID-19, only now we have one more reason to further strengthen these measures," said Fernández, adding that on the part of the National Government, genomic surveillance, intelligent sampling, and the study of contact chains are being reinforced.

About Omicron

The first thing to say is that there is considerable uncertainty about the clinical and epidemiological behavior of Omicron, but there is already recent information delivering some indications.

"In the first place, we know that it has certain biological characteristics, because it has a very large number of mutations, about 30 in the spike, and many are related to delta and gamma," said Fernández.

On the other hand, in South Africa a very rapid increase in the number of cases has been identified that could be related to greater transmissibility and effectiveness in contagion.

A more recent study suggests a potential risk of Sars-CoV-2 reinfection. "It seems to be more common in people who had the infection but did not get vaccinated," he explained.

Transmissibility could be higher; some studies even suggest that it is 1.5 times more. Secondly, there could be a potential to evade the immune response, which would explain the increase in reinfections that are currently being observed in South Africa.

Studies so far have not suggested that the new variant is more severe, however, scientific evidence is needed to reach more conclusive analyzes. "But the fact that it is more transmissible is already worrying because there are going to be escalations in cases, hospitalizations, and deaths, mainly in the unvaccinated population. For this reason, vaccination is the best strategy," he said.