Once the virus binds to ACE2, the next step is to fuse with the cell, a process that begins when host cell enzymes cut the tips at two different sites, a process known as rupture. This shot starts the fusion machine. If the link is like a key to get into the padlock, the cut is like a wrench. “Without cuts at both sites, the virus cannot enter the cells,” says Vineet Menachery, a virologist at the University of Texas Medical School.
One of the mutations in the delta actually occurs at one of these fracture sites, and a new study that has not yet been reviewed this mutation shows that it improves fracture. And Menachery, who was not involved in the study, says he repeated those results in his lab. “So it’s a little easier to activate the virus,” he says.
Whether this improves contamination is not yet known, but yes. When scientists remove these rupture sites, the virus is less contagious and less pathogenic, Menachery says. It is therefore reasonable that changes that facilitate rupture would increase transmissibility.
Delta may also have the ability to prevent the body’s immune response from contributing to fuel transmission. Leakage of immunity means that it infects more cells and creates more viruses, which makes it easier for someone who carries that virus to infect someone else.
But vaccines still work
The good news is that the vaccine offers great protection against Delta. A new research in Public Health England shows that the Pfizer-BioNTech vaccine was 88% effective in preventing symptomatic disease due to Delta in fully vaccinated people. The AstraZeneca vaccine was slightly less protective. Both shots were 60% effective against the variant. The efficacy of one dose of both vaccines, however, was much lower, at only 33%.
However, in the US and the UK, about 42% of the population is fully vaccinated. In India, when the virus was exacerbated by the rapid spread of the Delta, 3.3% of the population got the full vaccine.
At the press conference, Fauci asked those who did not receive the vaccine to give the first shot and reminded those who were partially vaccinated not to skip the second dose. The Biden Administration expects at least 70% of the population to be vaccinated by 4 July. In the UK, Delta was quickly replaced by Alpha to become the main strain and the cases are growing. “We can’t let that happen in the United States,” Fauci said.