WHO says making contingency plans for possible 'chemical assaults' in Ukraine - REUTERS
The World Health Organization said on Monday that it is monitoring a small number of cases of two novel sub-variants of the highly transmissible Omicron coronavirus strain to see if they are more infectious or deadly.
BA.4 and BA.5, sister variations of the original BA.1 Omicron variant, have been added to its monitoring list. BA.1 and BA.2, which are now worldwide dominant, as well as BA.1.1 and BA.3, are already being tracked.
Viruses mutate all the time but only some mutations affect their ability to spread or evade prior immunity from vaccination or infection, or the severity of disease they cause.
For instance, BA.2 now represents nearly 94% of all sequenced cases and is more transmissible than its siblings, but the evidence so far suggests it is no more likely to cause severe disease. read more
Only a few dozen cases of BA.4 and BA.5 have been reported to the global GISAID database, according to WHO.
The UK’s Health Security Agency said last week BA.4 had been found in South Africa, Denmark, Botswana, Scotland and England from January 10 to March 30.
All the BA.5 cases were in South Africa as of last week, but on Monday Botswana’s health ministry said it had identified four cases of BA.4 and BA.5, all among people aged 30 to 50 who were fully vaccinated and experiencing mild symptoms.
