- According to recent research published in the journal Nature, individuals with the Delta version may spread the virus for almost two days before showing symptoms.
- Presymptomatic transmission is thought to account for approximately 75% of Delta variant infections.
- Because of increased viral levels, vaccinated individuals with uncommon “breakthrough” illnesses may spread the virus just as readily as unprotected people.
Vaccines, according to experts, remain our greatest available weapon for controlling the spread of COVID-19 and protecting individuals from severe illness, hospitalization, and death. People infected with the Delta form of the coronavirus may be able to spread the virus for up to two days before developing symptoms. According to new research published in the journal Nature, this shift may be a significant factor in the recent increase of COVID-19 cases.
Previous coronavirus variations had presymptomatic transmission. However, the study found that getting a positive test and experiencing sick was just 0.8 days. It takes 1.8 days with the Delta version. Consequently, almost three-quarters of Delta infections occur within the presymptomatic period, according to the study.
“The Delta strain is more infectious, in part, because infected people carry and shed more virus than earlier versions,” said Dr. Steffen Ammon, medical director of Dispatch Health, an on-demand healthcare service.
“While the previous form of COVID-19 was as infectious as the common cold, the Delta variation is more contagious than seasonal influenza, polio, smallpox, Ebola, and bird flu, and is as contagious as chickenpox,” said.
Vaccines are still effective, but the spread of the disease remains a worry. Delta has become the prevalent variation globally as a result of its enhanced transmissibility. It is responsible for more than 90% of COVID-19 cases in the United States. While vaccinations are still highly successful at avoiding COVID-19 hospitalization and death, studies indicate that vaccinated persons who acquire the coronavirus, so-called “breakthrough infections,” may have viral levels as high as unprotected people, implying that they may spread the illness.
“When COVID-19 vaccinations initially became available, they showed a remarkable capacity to protect the receiver from acquiring any form of COVID-19, which essentially eliminated vaccinated exposures from the equation,” Ammon said to the Health line.
“However, the Delta variation has acquired a capacity in certain cases to partly escape the immunity given by vaccination, implying that there are more breakthrough infections in vaccinated people from the Delta variant than from earlier forms of the virus,” he said.
However, it is not all terrible news.
Recent studies indicate that receiving the COVID-19 vaccination is essential for both personal health and limiting transmission.
“It is not surprising that asymptomatic individuals transmit the virus. We’ve known for over a year that individuals are contagious before they show symptoms,” said Dr. Jason Gallagher, an infectious disease expert and clinical pharmacy specialist in infectious diseases at Temple University Hospital in Philadelphia.
According to a thorough study of an epidemic in Guangdong, China1, individuals infected with the Delta form of SARS-CoV-2 are more likely to transmit the virus before exhibiting symptoms than those infected with previous variants.
“It is just more difficult to stop,” says Benjamin Cowling, an epidemiologist at the University of Hong Kong and co-author of the research, which was published on a preprint site on August 13.
Cowling and his colleagues examined extensive test data from 101 persons in Guangdong infected with Delta during May and June of this year, as well as data from those people’s close connections. They discovered that, on average, individuals started experiencing symptoms 5.8 days after Delta infection – 1.8 days after they initially tested positive with virus RNA. Individuals had almost two days to eliminate viral RNA before showing any signs of COVID-19.
A Difficult Window
Before Delta emerged, individuals infected with SARS-CoV-2 took an average of 6.3 days to develop symptoms and 5.5 days to test positive for viral RNA, leaving a narrower window of 0.8 days for oblivious viral shedding earlier study2 and an unpublished analysis by Cowling and others.
In addition, individuals infected with Delta had more significant quantities of viral particles, or viral load, in their bodies than those infected with the original form of SARS-CoV-2. “Somehow, the virus is emerging faster and in greater quantities,” Cowling adds.
Consequently, 74 percent of Delta infections occurred within the presymptomatic period, a more significant percentage than earlier versions. According to Barnaby Young, an infectious-disease physician at Singapore’s National Centre for Infectious Diseases, this high rate “helps explain how this variation has been able to outrun both the wild-type virus and other variants to become the dominant strain globally.”