The World Health Organization (WHO) is closely monitoring a new variant of Covid-19. The B.1,621 strain, also called Mu, was first identified in Colombia in January. According to the WHO, the strain classified as a variant of interest has caused sporadic cases and outbreaks in South America and Europe.
A strain of SARS-CoV-2 is defined as a variant of interest when it has mutations in the genetic material with established or suspected implications for virus behavior, such as high incidence of transmission in one location, multiple lineage-related cases, and detection in many countries.
The Mu variant is becoming increasingly prevalent in Colombia and Ecuador, where it accounts for about 39% and 13% of cases, respectively. In addition, the strain showed signs of possible resistance to the vaccines. The information is from the WHO weekly epidemiological bulletin, published on Tuesday (31).
Potential for greater resistance to vaccines
The Mu strain has a series of mutations that suggest potentially greater resistance to vaccines. However, WHO emphasizes that further studies are needed to confirm this indication.
According to the preliminary data evaluated, the available vaccines against Covid-19 would have a reduced efficacy similar to what has been observed by the analyzes carried out with the Beta variant, first identified in South Africa.
“The Mu variant has a constellation of mutations that indicate potential immune escape properties. Preliminary data presented to the Virus Evolution Working Group show a reduction in the neutralizing capacity of convalescent and vaccinated sera similar to that observed for the Beta variant, but this needs to be confirmed by further studies”, says the WHO report.
Monitoring the evolution of SARS-CoV-2 is carried out in real time by researchers from various institutions around the world. One of the main sources of information about the virus is the GISAID portal, which provides open access to genomic data on the coronavirus and influenza virus, which causes the common flu.
According to GISAID, until the 29th of August, more than 4,500 sequences of the Mu variant (3,794 of the B.1,621 lineage and 856 of the B.1,621.1 sublineage) were deposited on the platform, based on the analysis of virus samples from patients with Covid-19.
With this information, virologists are able to track the variant’s path around the world and estimate where it might spread. Most of the sequences available on the platform were reported in the United States, Colombia, Mexico and Spain.
The interest variant rating is one level below the concern variants (Alpha, Beta, Gamma, and Delta). The latter present changes that can affect the properties of the virus, with one or more implications, including increased transmission capacity or disease severity, as well as impacts on the effectiveness of vaccines, drugs and diagnostic methods.