June 14, 2022
Coronavirus reinfections will likely increase throughout the summer as two Omicron subvariants — BA.4 and BA.5 — become dominant in the U.S.
The subvariants appear to be escaping immunity from vaccines and previous infections — even other Omicron infections — and have been causing hundreds of thousands of new COVID-19 cases in recent weeks, according to Yahoo News.
"The BA.4/5 variants, the next chapter of the pandemic in the US and Europe, is a story of immune escape," Eric Topol, MD, founder of the Scripps Research Translational Institute, wrote in a Twitter post.
BA.4 and BA.5 now account for nearly 22% of new COVID-19 cases nationwide, according to the latest CDC data, with BA.5 making up 13.3% of cases and BA.4 making up 8.3% of cases. The previous week, the two variants accounted for 13% of cases.
During the last month, the proportion of BA.4 and BA.5 cases in the U.S. has been doubling about every 7 days, which signals exponential growth, the news outlet reported. By July, the two subvariants will likely become dominant nationwide.
So far, the subvariants appear to cause less severe disease and death. Despite higher case levels, there are fewer COVID-19 patients in intensive care units than at other times during the pandemic, and the daily death rate continues to hover around 300.
At the same time, recent studies have pointed to potential concerns for serious illness due to mutations in the spike proteins of BA.4 and BA.5, Yahoo News reported. The two subvariants are about four times more resistant to antibodies, compared to BA.2, which means that breakthrough cases will likely become more common.
BA.4 and BA.5 also appear to be better at replicating in lung cells than the original Omicron variants. The subvariants also seem to be mutating in a way that makes them more resistant to monoclonal antibody treatments such as Evusheld and antiviral treatments such as Paxlovid.
The outlook in different countries has provided conflicting forecasts for what could happen in the U.S., the news outlet reported. Portugal is having a BA.5 wave and a high number of deaths despite high vaccination rates, yet South Africa's death rate remained fairly flat during a recent BA.4 spike. That said, the U.S. population more closely aligns with Portugal's demographics in terms of an older population.
As the pandemic moves forward, public health experts have suggested next-generation vaccines, better ventilation, and masks to reduce transmission in upcoming waves.
"If we are going to have waves every few months, we need to do something 'sustainable' to reduce transmission," Christina Pagel, PhD, a COVID-19 expert and director of the Clinical Operational Research Unit at University College London, wrote in a Twitter post.
"It's an airborne virus and spreads far more easily indoors, and we need to address that," she wrote.
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