WHO: Delta is "by far" the most transmissible variant of the coronavirus

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(CNN) -

The delta variant is "by far" the most transmissible variant of the new coronavirus SARS-CoV-2, said Maria Van Kerkhove, technical chief on covid-19 at the World Health Organization (WHO), during a question and answer session on social media this Tuesday.

"Delta is predominant around the world so far, based on all the available sequences that have been shared," Van Kerkhove noted.

"Of the four variants of concern, again, you know that delta is by far the most transmissible. It has been reported in more than 185 countries to date."

The four variants of concern are alpha, beta, gamma and delta, he added.

But if you look at the globally shared available sequences, delta is the predominant circulating virus, "and in fact less than 1% of the sequences available right now are alpha, beta and gamma. So less than 1% alpha, beta and gamma is currently circulating. In fact, delta predominates throughout the world. "

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Van Kerkhove also explained that the delta variant is "displacing, it is replacing the other viruses that are circulating."

"For example, if delta is identified or begins to circulate in a country where there is beta, in South Africa for example, it has quickly replaced the variant there," said the WHO official.

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Several variants of interest are also being screened, he said, including the lambda and mu variants.

However, delta continues to outperform mu in countries that have both variants, Van Kerkhove explained.

"Right now, lambda and mu are variants of interest, but they don't appear to be dominant, as delta is," he said.

Three old variants of interest - eta, iota and kappa - are being reclassified as tracked variants, he said, something that will be announced in the WHO weekly status report.

"This is really due to changes in circulation as variants of interest are being overtaken by variants of concern, they are just not catching on," he said.

coronavirus Delta variant