News -- April 12, 2022: Stealth Omicron -- Its formal designation is BA.2, however due to a mutation that causes it to appear differently in lab tests than its sibling strain, some scientists have called the subvariant "stealth omicron."It's currently the most common coronavirus strain in the United States and more than a half-dozen other countries.
According to Kristen Coleman of the University of Maryland School of Public Health, it was given the label "stealth" because it seems to be the earlier delta variation on certain PCR tests. The original omicron, on the other hand, is easy to distinguish from delta due to a genetic anomaly.
Cases of COVID-19 caused by BA.2, however, are on the rise in a handful of countries, including the U.S., where it now accounts for more than 70 percent of all new COVID-19 infections, up from about 1.5 percent in early February.
BA.2 is more contagious
There is “growing evidence” that BA.2 is more transmissible, or contagious, than the original omicron variant, Mark McClellan, M.D., director of the Duke-Margolis Center for Health Policy, said during a media briefing, pointing to places in Europe “where BA.2 has now taken over much of the continuing caseload.”
For example, the BA.2 variant went from making up about 20 percent of all new coronavirus infections in Denmark to nearly half in a matter of weeks, according to the Statens Serum Institut, a public health and research agency under the Danish Ministry of Health. And in England, BA.2 was responsible for about half of COVID-19 cases in late February; by early March, that percentage was closer to 80.
Disease Control and Prevention Director Rochelle Walensky said that it’s not nearly the transmission advantage that we’ve seen between omicron and delta.” A study out of Denmark that has yet to be peer reviewed found omicron to be between 2.7 and 3.7 times more infectious than delta, which was already declared by the CDC to be twice as contagious as previous variants.
According to studies from the United Kingdom, following two doses of the mRNA vaccines, protection against symptoms from a coronavirus infection caused by BA.1 was around 9%; for BA.2, it was around 13%. After a booster, the protection against symptomatic sickness caused by BA.1 increased to 63 percent and 70 percent for BA.2. According to the same study, boosted adults aged 50 and older had a 95% chance of surviving an omicron infection.
Wnctimes by Marjorie Farrington