Written By: Longjam Dineshwori | Updated : May 4, 2022 11:24 AM IST
COVID-19 cases are rising again in the US, thanks to a new highly transmissible subvariant of Omicron that is spreading rapidly across the country. Called BA.2.12.1, the new strain accounted for 36.5 per cent of new COVID-19 cases recorded in the country in the week ending April 30, revealed the latest data released by the US Centers for Disease Control and Prevention (CDC).
A week before, the new Omicron subvariant was held responsible for 26.6 per cent of Covid-19 cases in the US and 16.7 per cent two weeks prior, CDC data showed.
Yet, the majority of COVID cases in the US are caused by BA.2, accounting for around 61 per cent of new infections. This variant, a sublineage of Omicron variant of concern, has been circulating as the dominant variant in the country since March. More cases of BA.2.12.1 are being reported the Northeast regions.
Omicron is made up of several sublineages, each of them is being monitored by WHO and partners. Earlier, the WHO's Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE) had emphasized it will continue to closely monitor BA.2 as a distinct sublineage of Omicron and had also requested countries to continue to be vigilant and conduct independent and comparative analyses of the different Omicron sublineages.
According to the CDC data, the US is seeing on average about 60,000 new infections and 320 new deaths each day as of Monday.
In the New York, the emergence of this subvariant was first announced in mid-April. According to the New York State Department of Health, it accounted for 41.6 per cent of new infections across the state as of April 23.
Due to the additional mutations BA.2.12.1 possesses, it is considered to be of higher concern, the department has said.
CDC Director Rochelle Walensky suggested that BA.2.12.1 appears to be about 25 per cent more transmissible than the BA.2 subvariant. However, he noted that additional evaluation is currently underway to understand the impact of BA.2.12.1 on vaccine effectiveness.
Besides BA.2.12.1, the emergence of a pair of new Omicron subvariants (BA.4 and BA.5) has raised concern that people infected by earlier Omicron strains can get reinfected. These two Omicron subvariants are spreading rapidly in South Africa, where weekly Covid-19 cases have tripled in the last two weeks.
Although few cases of BA.4 and BA.5 have been reported in the US, experts have predicted a potential surge in the coming days.
Zhang Zuofeng, chair of the Department of Epidemiology at the University of California, Los Angeles, told Xinhua on Tuesday that BA.4 and BA.5 subvariants are more contagious than BA.1 and BA.2, and have a better shot at evading existing immunity.
He suggested that unvaccinated people who have been infected by Delta, and earlier Omicron strains like BA.1 or BA.2, may be more prone to reinfection by these contagious strains. But, as the virus stays in the upper respiratory tract and causes less lung infection, it is less likely to lead to severe diseases and deaths, Zhang told the news agency.
Zhang added the BA.1 and BA.2 variants may cause an increase in new infections in the US, but not like the outbreak caused by the original Omicron variant in January.
