The Delta variant’s quick dominance over other COVID-19 strains in the United Kingdom (U.K.) is sparking concerns that the U.S. could be hit with a similar wave of new cases in the coming months.
Public health experts are projecting that the highly transmissible variant will soon overtake the Alpha strain in the U.S. and later become the dominant form of the coronavirus.
The Delta strain has the potential to cause outbreaks in places with lower vaccination rates since fully vaccinated people appear to have protection against it.
Anthony FauciAnthony FauciDelta variant's UK dominance sparks concerns in US Overnight Health Care: FDA says millions of J&J doses from troubled plant must be thrown out | WHO warns Africa falling far behind in vaccinations | Top CDC official says US not ready for next pandemic Top CDC official warns US not ready for next pandemic MORE, President BidenJoe BidenEx-Biden adviser says Birx told him she hoped election turned out 'a certain way' Cheney rips Arizona election audit: 'It is an effort to subvert democracy' News leaders deal with the post-Trump era MORE’s chief medical adviser, said the Delta strain currently makes up more than 6 percent of U.S. coronavirus infections.
But the number of Delta cases in the U.S. is surging, much like it previously did in the U.K., which reported on Friday a 240 percent increase in these cases in just one week. The Delta variant now makes up more than 90 percent of all COVID-19 cases in the U.K.
Eric Feigl-Ding, an epidemiologist and senior fellow at the Federation of American Scientists, said he expects a surge in Delta cases in the U.S. late next month or in August.
“If the U.K. is where we should draw our lessons, I think the U.S. is in for a surge in the lower vaccinated states,” he said.
The rise in U.K. cases, he added, is a sign that its vaccination rate “currently is not enough to slow it down.”
In the U.K., 78 percent of adults have received at least one vaccine dose, and 55.4 percent are fully vaccinated. Among U.S. adults, 64 percent have received at least one dose, and 53.4 percent are fully vaccinated.
“What it means is the U.S. is not invulnerable from the invasion of the Delta variant and from surges from the Delta variant,” Feigl-Ding said, noting that he hopes U.S. vaccines keep the total cases “under control.”
Still, early research indicates the Delta variant, first identified in India in October, could be 60 percent more transmissible than the Alpha variant that became the dominant strain in the U.S. two months ago.
The U.K. has confirmed 35,364 new Delta cases over the past two weeks, compared with 12,854 new Alpha cases. At the same time, the seven-day average for daily confirmed COVID-19 cases has jumped by more than 4,600 cases since May 19, according to Our World in Data.
Preliminary figures also suggest that those infected with the Delta variant may be at a higher risk of being hospitalized than those who catch the Alpha strain, according to Public Health England.
Fauci said during a briefing this past week that the Delta variant is “essentially taking over” the U.K.
“We cannot let that happen in the United States,” he said.
Experts believe the Delta variant contributed to the outbreak in India earlier this year, and the World Health Organization said this past week that it has spread to at least 74 countries.
In the U.S., the Delta strain reached 0.1 percent of all cases in early April, and by the end of May, it made up 2.5 percent of all infections, according to estimates from the Centers for Disease Control and Prevention. The agency’s projection for the two-week period ending June 5 was that 6.1 percent of all COVID-19 cases were Delta.
Experts agree that full vaccinations appear to be effective against the strain, especially in preventing serious illness and death.
A preprint study from Public Health England determined that people fully vaccinated with Pfizer-BioNTech and AstraZeneca vaccines were 88 percent and 60 percent effective against symptomatic Delta cases, respectively.
But the research found partially vaccinated people with one shot had fewer protections from the variant, with both vaccines being 33 percent effective against symptomatic disease.
Based on that study, David Holtgrave, dean of the University at Albany School of Public Health, called on Biden in a CNN op-ed to refocus his goal to get at least 70 percent adults one dose by the Fourth of July and instead set a target for fully vaccinated people.
“We must urgently pivot our policy, programmatic and communication efforts to address the novel challenges now posed by the Covid-19 Delta variant before it becomes even more widespread,” he wrote. “There is no time to lose.”
Andrew Pekosz, a professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health, said with the U.S. vaccine stockpile no longer limited, officials should prioritize second doses.
“It's clear now that going forward there really is one path, and that's get the double dose as efficiently as possible,” he said.
Another point of concern is that the U.K. is seeing a surge among 12-to-20-year-olds, as most are not yet eligible to get the vaccine. Within the past week, 77 outbreaks were documented in U.K. educational settings.
In the U.S., everyone 12 and older is authorized to get the vaccine. Biden cited the spread of the Delta strain in a plea to young people to get vaccinated, tweeting, “If you’re young and haven’t gotten your shot yet, it really is time.”
Pekosz of Johns Hopkins University said it will be important to monitor how the Delta variant spreads among children; those under 12 are not yet eligible to get vaccinated but are expected to return to classrooms this fall.
“If it does turn out to be that this virus can infect children more efficiently, then that would really make protecting those populations something that has to be prioritized from a government perspective,” he said.
Christina Ramirez, a professor of biostatistics at the UCLA Fielding School of Public Health, called for more sequencing to get better data on which variants are spreading, where there are hot spots and which strains might be thwarting the vaccines.
To prevent a variant from emerging that’s resistant to the vaccines, she suggested sending doses globally to countries enduring surges.
“Our best defense is to really vaccinate places that are having uncontrolled outbreaks because this is where our next variant is really going to come from,” she said.