June 7th CDC Nowcast Of COVID Variants In the U.S.
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Omicron BA.2.12.1 is currently dominant in the United States, but two newer subvariants (BA.4 and BA.5) are rising, with BA.5 expected to capture the top spot here - and internationally - in the coming weeks.
This incessant, and rapid changing of the guard means that what we could say about COVID's transmissibility, severity, or immune escape yesterday may not hold true a month from now.
Two weeks ago, in Preprint: Virological Characteristics of the Novel SARS-CoV-2 Omicron Variants including BA.2.12.1, BA.4 and BA.5, we looked at in vitro and hamster studies (using lab-created chimeric recombinant SARS-CoV-2 viruses to approximate each subvariant) conducted at the Kei Seto Lab at the University of Tokyo, which suggested higher virulence (in hamsters) for the BA.4/5 variant.
How well this study's increased pathogenicity findings in hamsters will translate to humans remains to be seen. But evidence of BA.4/5's increased transmissibility and its ability to evade prior immunity seems more solid.
Today Denmark's SSI has released their own Risk Assessment, which finds - for the time being, at least - no evidence of increased severity, but does warn that case numbers are expected to rise as BA.5 becomes the dominant strain in that country in a matter of weeks.
Risk assessment of the omicron subvariants BA.5, BA.2.12.1 and BA.4
The Statens Serum Institut has made a risk assessment of a number of omikron sub-variants that are currently growing in Denmark. It is estimated that BA.5 will become the dominant variant within a few weeks. However, there is no evidence that this variant is more serious than the original omicron variants BA.1 and BA.2, SSI estimates.Last edited June 10, 2022
After the number of new covid-19 cases has fallen week after week since the beginning of February, the number of infections has now started to rise again.
This is due to the fact that during May there has been a marked growth in the number of cases of infection with the three omicron subvariants BA.5, BA.2.12.1 and BA.4.
Therefore, the Statens Serum Institut (SSI) has made a risk assessment for the three sub-variants.
See the new risk assessment (pdf).
The situation internationally
It is not only in Denmark that BA.5 is rising. The same pattern is seen in a number of other European countries.
"Both BA.4 and BA.5 appear to be less sensitive to both the immunity people have received through the covid-19 vaccines and the immunity of having been infected in the past," said Tyra Grove Krause, SSI's professional director.
"However, the vast majority of the proven BA.5 cases in Denmark are still among people who have not been infected before," says Tyra Grove Krause.
Based on the development in South Africa and Portugal, among others, and BA.5's growth in Denmark, SSI estimates that there is a high probability that BA.5 will become the dominant covid-19 variant in Denmark within a few weeks.
"We also assess that there is a high probability that the number of new covid-19 cases will generally increase in the coming weeks," says Tyra Grove Krause.
Subvariants no more serious
For the time being, SSI does not consider that there are any signs that the new variants are more serious compared to the original omicron variants BA.1 and BA.2.
"Currently, there is no evidence that the new sub-variants, and especially BA.5, give more serious disease courses than BA.1 and BA.2. We assess this both on the basis of the international reports and on the basis of the so far small figures from Denmark, ”says Tyra Grove Krause.
More cases mean more hospitalizations, and deaths, even if this subvariant proves to be no more virulent than BA.1/2. And already, here in the United States, we are seeing a rise in hospitalizations.
How long BA.5 will reign, and what will replace it, are big unknowns. But based on the patterns we've seen over the last six months, we will probably be watching a new viral contender by the fall.
