The Centers for Disease Control and Prevention (CDC) announced that Omicron subvariants strains, BA.4 and BA.5, have taken over as the predominant strains in the United States. Currently, BA.5 accounts for 54% of new cases, and BA.4, its sister subvariant, is responsible for 16% of the infections.
BA.4 and BA.5 Subvariant in US
According to the study published on Nature's website, BA.4 and BA.5 were substantially 4.2-fold more resistant to antibodies. In effect, it may evade vaccine protection. Compared to most of their predecessors, the two subvariants appear to be able to avoid immunity from vaccinations and prior infections.
Breakthrough infections will occur more frequently in people vaccinated and boosted with currently available mRNA vaccines as these highly transmissible subvariants continue to spread around the globe, according to the study's lead author David Ho, MD, director of the Aaron Diamond AIDS Research Center at Columbia University.
Professor David Montefiori of the Human Vaccine Institute at Duke University Medical Center said it is more contagious than earlier versions of omicron. He said that the omicron variants BA.4 and BA.5 are around three times less vulnerable to neutralizing antibodies from the current vaccines than the original form, BA.1.
The subvariants could cause serious problems in older, unvaccinated individuals. The state's department of health and human services, Nevada, reported that the hospital admissions in Clark County increased for the second week in a row, the week ending July 8. The infected people were unvaccinated adults aged 70 and older, making up most of these admissions.
BA.4 and BA.5 Subvariant in UK
The BA.4 and BA.5 also make up the majority of new cases in the UK. Francois Balloux, director of the University College London Genetics Institute, said all variants were equally transmissible at this point. Although there's no significant difference, he said that some are a little better at infecting those who received a vaccine or were infected by the previous variants.
Based on the Zoe COVID Symptom Study data, less than one-third of trial participants reported having a fever. Yet, they experienced typical symptoms such as runny nose, sore throat, headache, persistent cough, and exhaustion.
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BA.4 and BA.5 Reaction to Vaccines
Peter Chin-Hong, MD, an infectious disease specialist at the University of California in San Francisco, stated in an interview with Nexstar Media Wire that a person who had omicron in January would still be susceptible to having BA.4 and BA.5. Because the spike protein is different, the antibodies were not recognizing it.
Infectious disease expert William Schaffner, MD, sees the spread of BA.4 and BA.5 as both a positive and negative development. He said that although the existing vaccines less strongly protect the BA.4 and BA.5 variations, the vaccines help in keeping people out of the hospital.
The CDC advises residents of high-transmission areas to keep a distance of six feet between outsiders and members of their household. The health department keeps reminding everyone that even those who are symptom-free might spread the illness.
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