Medical experts are trying to find out if the new Delta variant will make people sicker and whether it is more fatal and dangerous.
The new Delta variant has been identified in 80 countries so far and is known to grow more swiftly than other strains of COVID-19. It is currently this variant that is causing most new infections in the UK and represents about 20% of new infections in the US.
Medical experts are still trying to figure out if this Delta variant makes people more ill or whether it is deadlier and more fatal. It was first identified in India, this more transmissible form of the novel coronavirus has spread to at least 80 nations and now makes up more than 20 percent of all U.S. cases.
The Centers for Disease Control and Prevention has identified it as a “variant of concern.” If vaccination measures neglect to keep pace with its spread, experts say, the variant could lead to new COVID surges in parts of the country where a substantial proportion of the population remains unvaccinated. This is why speedy vaccination is key to curbing COVID.
Studies to date imply the Delta variant is between 40 and 60 percent more transmissible than the Alpha variant first identified in the U.K.—which was already 50 percent more transmissible than the original viral strain first detected in Wuhan, China.
Delta has suddenly become the dominant variant in the U.K. and has led to a new flood of cases there, despite the population’s high vaccination rate, and now is rapidly growing more widespread in the U.S.
A preprint study, which has not yet been peer-reviewed, found that Delta and another variant called Gamma, first identified in Brazil, are fast replacing Alpha, which had previously been the most common U.S. variant. If the prevailing situation continues, Delta will likely become the country’s dominant variant in a few weeks, according to William Lee, vice president of science at the genomics company Helix, who co-authored the study.
“It is the most hypertransmissible, contagious version of the virus we’ve seen to date, for sure—it’s a superspreader strain if there ever was one,” says Eric Topol, a professor of molecular medicine and an executive vice president at Scripps Research Institution. The U.S. is poorly prepared, he says. Less than half of the nation’s population is fully vaccinated—and that number is much lower in some states, particularly in the South and Mountain West. “We’ve been warned three times by the U.K.,” Topol says, referring to previous surges in early 2020 and last winter. “This time is the third warning.”
There is a suggestion that the Delta variant may also result in more severe disease. A study in Scotland, published in the Lancet, found the hospitalization rate of patients with that variant was about 85 percent higher than that of people with the Alpha variant. But because of the time lag between hospitalizations and deaths, there is not enough data to say whether or not Delta is more deadly than other variants.
Aziz Sheikh, a professor of primary care at the University of Edinburgh and lead author of the Lancet study said, “The thing we were surprised by is just how rapidly the Delta variant took hold….We were again in an exponential phase of growth of cases.” This should be a lesson for the U.S.”
The good news is the vaccination appears to provide good protection against Delta—although one dose seems to offer less protection than it did against other variants. A preprint study by Public Health England found that two doses of the Pfizer-BioNTech vaccine and two doses of the AstraZeneca vaccine were 96 percent and 92 percent effective, respectively, at preventing hospitalization in people infected with Delta That result is comparable to the level of protection seen against other variants.
Meanwhile, a single dose of the AstraZeneca vaccine was only 71 percent effective against hospitalization caused by Delta (a single dose of Pfizer was still 94 percent effective), and one shot of either vaccine was only about 33.5 percent effective against symptomatic COVID from that variant, highlighting the importance of getting both doses. The U.K., which had postponed second doses in an effort to vaccinate a larger portion of its population quickly, has now delayed its reopening plans by four weeks to allow time for more people to get both doses.
Several experts stated they do not expect the Delta variant to cause a nationwide surge in the U.S. like the one that transpired last winter. But they do predict localized outbreaks in places where vaccination rates remain low. “I think it really is going to depend on a community-to-community basis,” says Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization–International Vaccine Center in Saskatchewan.
The outcome will also depend on the climate and people’s behavior, she said. In hot places where people spend a lot of time in air-conditioned buildings and vaccination rates are low—such as parts of Arizona and Texas—“I think we’ll definitely see local surges,” she says. But in San Francisco or New York City, where a large percentage of the population is fully vaccinated, she believes it will be a lot harder for the virus to gain a footing.
Vaccination remains the best tool for fighting a Delta surge, according to medical experts. The youth in the U.K. who have been resisting vaccines have more cases and U.K. data indicate most of the Delta cases have been in younger people, who are less likely to have been vaccinated. In the U.S., adults aged 18 to 29 have had the lowest vaccination rates of any age group, a recent CDC report found. Members of this group have a lower risk of severe disease or dying from COVID, but they can still be hospitalized and are at risk of developing a long-lasting sickness and symptoms.
Experts say the Delta variant poses a relatively low threat to fully vaccinated people. “You should not worry at all” Immunocompromised people still need to be somewhat careful even if they are vaccinated because they may not have developed strong immunity from the vaccine.
Based on initial studies, it is believed COVID-19 vaccinations are effective against the Delta variant. Top US health institute says India’s Covaxin, developed by Bharat Biotech in collaboration with the Indian Council of Medical Research, effectively neutralizes both Alpha and Delta variants of coronavirus, and the same is claimed by vaccine experts in India.