Less than a week ago, the first confirmed case of coronavirus was reported with variant B.1.1.529, called by the World Health Organization (WHO) as omicron. This new strain detected in South Africa has been described by the international organization as “worrying” due to the global risk it poses.
As with other viruses, the original SARS-CoV-2 has undergone mutations throughout these months, some of which have been considered of interest or concern. “Most of the changes have little or no effect on the properties of the virus , but some changes may influence some of them, such as its ease of spread, the severity of the associated disease or the efficacy of vaccines,” he points out. The OMS.
In this sense, omicron has become the fifth variant classified as worrisome by the WHO, which monitors and monitors the evolution of the original strain since January 2020. Thus, at the end of that same year, the organization began to use the categories “Variant of Interest” (VOI) and “Variant of Concern” (VOC) to monitor the virus on a global scale and guide the response to the pandemic.
Likewise, the group of experts appointed by the WHO uses names based on the Greek alphabet to designate the variants and thus avoid stigmatization with the country of appearance. These are the worrisome variants currently designated by the WHO:
This strain was first detected in the UK in September 2020 and was popularly known as the British variant. However, it was not designated as a VOC (variant of concern) until December 18, 2020 . It spread to practically the whole planet and it was later found that the effectiveness of vaccines does not diminish.
This variant was detected in Brazil for the first time in November 2020, but until January 11, 2021 it was not classified as worrying because it has a higher transmissibility.
This was the first strain to be detected in South Africa and it was designated as of concern in December 2020. The majority of confirmed cases with this strain have been identified in South Africa. It is known to have a mutation (E484K) related to moderate escape from the immune system response to vaccines and is believed to be more contagious than other variants.
The so-called Indian variant was the one that most concerned practically the entire planet this summer and is the predominant one in almost 100% of the cases detected in Spain. It was first documented in India in October 2020, but it was not until April 4, 2021 that it was listed as a worrying variant.
It has greater transmissibility and a possible reduction in the effectiveness of vaccines. In addition, its incubation period is shorter and it has different symptoms from the rest of the strains.
Lambda and Mu: variants of interest to WHO
In addition to these five strains of greatest concern, the WHO has also cataloged two variants of interest: Lambda and Mu. This type of strains are those that “present changes in the genome that affect the characteristics of the virus” and that may cause a new risk for public health in the future.
The Lambda variant was initially registered in Peru in August 2020 , but has not been shown to be significantly transmissible . Variants that the WHO qualifies as “of interest”, such as this strain, “lead to significant transmission,” according to the organization, and can also cause “several clusters of covid-19 in different countries, with a growing relative prevalence and causing increasing numbers of cases over time, “he says.
For its part, the Mu strain was first detected in Colombia in January 2021. Since then it has been detected in 40 countries, but it is believed that it is currently responsible for only 0.1% of infections worldwide, therefore which is not considered worrisome.