The COVID-19 pandemic continued to spread globally this week, except in Africa, which was the first region to see a decline in cases following the Omicron wave. Approximately 2.8 million daily cases were reported worldwide, representing an increase of 44% from the previous week, according to the latest statistics. Cases rose in all regions, but only Africa, where the Omicron variant first appeared, recorded an improvement in the epidemiological situation with an 11% decrease in infections.
Researchers from the Fred Hutchinson Cancer Research Center, part of the COVID-19 Prevention Network in the U.S., and the South African AIDS Research Program, found evidence explaining why the Omicron variant spreads much faster than previous variants. Data observed in a study published on January 10 on the preprint site "medRxiv" indicate that asymptomatic individuals infected with the virus are more likely to transmit the infection to others compared to previous variants, as reported by "Al-Sharq Al-Awsat".
The researchers used PCR testing from mid-November 2021 to December 7, 2021, on asymptomatic individuals and found the transmission rate was 16%. They then conducted a larger study between December 2 and December 17, 2021, and found that 31% of transmissions were asymptomatic (71 out of 230 samples), verifying that all samples available for sequencing analysis were Omicron.
The researchers stated that previous studies on asymptomatic transmission rates for the Beta and Delta variants ranged from 1% to 2.6%, which is 7 to 12 times lower than Omicron. The smaller sample study was a subset of a larger study assessing the efficacy of a single dose of a COVID-19 vaccine, evaluating immune responses and breakthrough infections in 1,200 healthcare workers, including pregnant or breastfeeding women and those with HIV. The study included 577 vaccinated individuals, and results indicate a higher transmission rate, even among the vaccinated.
Dr. Lawrence Corey, the study's lead author, stated in a report published by Health Day, concurrent with the study's release: "As we witness the rapid global spread of Omicron, it's clear that we need a much better understanding of the transmission dynamics of this variant." He added, "Because many people may be asymptomatic, we cannot always know who is carrying the virus, but we do know what we can do to protect ourselves and help prevent the spread of the disease, which includes wearing a mask, washing hands, avoiding indoor gatherings, and getting fully vaccinated as soon as possible."
Since its emergence in China in December 2019, the coronavirus has caused at least 5,519,380 deaths worldwide. The United States has recorded the highest number of fatalities from the virus at 846,488, followed by Brazil (620,545), India (485,350), and Russia (319,911). The World Health Organization estimates that the total number of deaths may be two to three times higher when considering the excess mortality associated with the pandemic.
