BA.2.12.1 in the United States would already be dominant in New York, where infections have never been higher since January. In South Africa BA.4 and BA.5 represent over 60% of infections which have gone from 1,000 to 10,000 in a week
Some countries in the world are grappling with one resurgence of infections from Covid due to the presence of Omicron sub-variants. The most evident rises, but also the ones that are best monitored, concern the USA and South Africa.
In the US never so many cases since January
According to the Centers for Disease Control and Prevention (CDC), Omicron 2 (BA.2) is dominant in the US at 62%, but the recent rise is due to a sub-lineage of this called BA.2.12.1 given at 37% (on April 30).
The new positives in one day reached over 120,000, a figure that hasn’t been seen since February. TO New York (where BA.2.12.1 would be 62% dominant) more than 10,000 new cases have been reported, the biggest increase in one day since January. In Florida, growth was 39% over the previous week.
The characteristics of BA.2.12.1
BA.2.12.1 has been identified a December and grew slowly but now reported in USA, Canada, Austria, Puerto Rico and Denmark. It contains some mutations that differentiate it from BA.2 including L452Q (and other mutations on L452). It is estimated to have an added benefit in contagious with respect to BA.2 25%. The overall data suggests that Omicron’s sub-variants are more resistant to antibodies compared to the previous strains and could pose further problems to vaccinated or infected people (and obviously to the unvaccinated) causing reinfections or infections. According to the scientists, this does not exclude the fact of remaining protected by vaccination against the risk of serious illness. In fact, hospitalizations in the US are growing but not at the level of infections and do not seem to have a trend that suggests a worsening of the pathogenic capacity of the virus.
BA.4 and BA.5: new growth in South Africa
The growth in the US is coupled with the increase in infections in South Africa (and not only) of two other Omicron sub-variants called BA.4 and BA.5, which with respect to BA.2 possess the mutations: deletion 69-70, L452R, F486V (in the spike) and R493. BA.4 and BA.5 differ from each other but are identical to each other in terms of spike mutations.
BA.4 was detected in January and arrived (in addition to South Africa) also in Denmark, UK, Belgium and the USA; BA.5 was taken over at February and has also reached Germany, Portugal, UK, France and the USA.
Currently in the African country they represent il 60-75% of cases and determine a rise of 10 thousand new positives per day and one 20% positive rate which just 10 days ago was at 5%.
From the first findings it emerges that also BA.4 and BA.5 they are more contagious than BA.2 and probably previous Omicron infections will not be enough to protect everyone from these sub-variants. However, South Africa, like the US, has a high immunity due to previous infections and vaccinations, immunity that has been shown to protect the population from the risk of developing a serious Covid disease. Symptoms currently appear similar and hospitalizations are in line with what would be expected and there is no indication that BA.4 and BA.5 are more lethal viruses.
May 7, 2022 (change May 7, 2022 | 10:40 am)
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