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  • COVID-19 cases in the United Kingdom have been rising sharply over the past few weeks but deaths remain lower than last winter’s peak.
  • The surge has largely been attributed to the premature easing of restrictions, less adherence to COVID-19 best practices, more mixing, and uneven vaccination coverage within different age groups.
  • The U.S.’ progress against COVID-19 has shown parallels with the U.K., with the Delta surge affecting the country a few months after.
  • Although most experts agree that the U.S. has likely experienced its peak for the year, a bump in case numbers like the U.K. could come around Thanksgiving and Christmas time.

The United Kingdom has fared relatively well with its COVID-19 vaccine program, but it has recently seen case numbers jump.

The number of daily cases surpassed 50,000 on Oct. 19. The7-day average stands at around 45,000 cases, according to official figures. This is up from 28,000 in mid-September.

In the United Kingdom, schools have a mid-term break in the fall. With schools out for break right now, experts are divided on what the COVID-19 picture will look like over the next few weeks.

Although some predict that case numbers could drop as the chain of transmission would be broken with families on vacation, some believe mixing with other populations could fuel another surge.

Dr. Monica Gandhi, an infectious diseases specialist with the University of California, San Francisco, said the decreases in cases just over the past week support the first argument.

“[I]t is possible that less mingling in schools during the holiday break is leading to that trend. However, with mitigation procedures in schools (such as testing), more transmission usually occurs in the community than in schools,” she said.

That means the surge cannot be attributed to children alone.

The recent upward trend in United Kingdom cases can likely be explained by a combination of factors.

One factor may be related to waning immunity from vaccines.

The United Kingdom was one of the first countries to roll out vaccines, administering them as early as December 2020. About 70 percent of the population had received their first dose by July 1.

Data from Israel shows that vaccine immunity may wane after about 5 to 6 months, though that does not mean the vaccines provide no protection. They appear to provide less protection compared to when the initial dose was administered.

The country has since ramped up its booster program, inoculating over 7 million people.

However, despite an enthusiastic start to mass immunization, vaccination progress has stalled. September and the first 2 weeks of October, in particular, saw a loss of momentum, with relatively few people over 12 years old being vaccinated.

Suboptimal vaccination coverage among children could also be contributing to the surge.

In the past week, the majority of COVID-19 cases have been in people younger than 20 years old. Vaccine uptake among children ages 12 to 15 years old remains low at less than 20 percent.

The United States is similar, with about 5 percent of 12- to 15-year-olds being fully vaccinated so far.

In the United Kingdom, 12- to 15-year-olds have begun to receive 1 dose of the vaccine from Sept. 20 onward. Whether via vaccination or natural immunity, this lack of protection among children makes surges more likely.

Dr. Eric Cioe-Peña, director of global health at Northwell Health in New Hyde Park, New York, said the surge in the United Kingdom was likely due to the country not yet breaking the herd immunity barrier, resulting in it still navigating occasional spikes.

Gandhi said that was likely for two reasons:

“One is that the U.K. just started vaccinating 12- to 15-year-old children, and I think that control of the Delta variant takes higher levels of immunity that requires the vaccination of younger people,” she said.

The second, she said, was a low rate of seroprevalence, or the percentage of people who had antibodies at the start of the vaccination campaign.

“Although the U.K. had high rates of vaccination prior to opening up in mid-July, it likely wasn’t high enough to achieve control with a 9.8 percent natural immunity rate prior to vaccination,” she noted.

According to epidemiologists such as professor Tim Spector from King’s College in London, the surge more likely stems from the United Kingdom’s “state of complacency,” which meant officials did not take other steps to stop the disease aside from relying solely on vaccines and boosters since July 19.

Since that date, dubbed “Freedom Day,” social distancing guidelines and other restrictions were relaxed. It marked an earlier relaxing of these measures compared to other countries such as Germany and Portugal. It also came when the more infectious Delta variant made up over 90 percent of cases.

Recent research has shown that fully vaccinated people who develop COVID-19 can still pass on the coronavirus in their household, which means wearing a mask remains crucial to stopping the spread.

The 7-day average of cases in the United States is down to just over 68,000 a day. This is far lower than the 161,000 cases being recorded in early September at the height of the Delta surge, according to the CDC.

“We’re seeing a sustained downward trend in new cases, hospitalizations, and deaths throughout most of the country, even in states such as Tennessee, my own, which is an under-vaccinated state,” said Dr. William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University’s Medical Center in Nashville.

He attributed this drop to two developments:

“The first is, day by day we’re vaccinating more people. We’re about now to start vaccinating younger children. In addition to the advancing vaccination program, this virus continues to spread. And every time it infects a new person, whether without symptoms, with mild symptoms, or severe illness, after those people recover, they have a measure of protection. So, both the vaccine and the virus are immunizing our population.”
– Dr. William Schaffner

Cioe-Peña agreed:

“[The recent decrease is] probably the natural ebb and flow of COVID-19 — we’ve seen it burn through a population in that time.”

Cioe-Peña said the United States should look out for increased cases in children going forward.

“There is evidence of increased transmissibility with the Delta variant in children. Surges of positive cases can also be asymptomatic or minimally symptomatic cases. So [in the United Kindgom], hospitalization and death [rates] are flat, but new infections are up,” he said.

Schaffner further explained:

“[D]elta is so contagious that it is now seeking out susceptible persons who are young adults, adolescents, and increasingly children. So, it clearly has such a contagious capacity that it is spreading in those groups, which had not been impacted substantially earlier, say 6 to 8 months ago. So it’s finding those individuals in our society who are unvaccinated, and there are many more younger adults, teenagers, and even children.”
– Dr. William Schaffner

Cioe-Peña, however, emphasized that a high vaccination rate was preventing surges in hospitalization and deaths in the United Kingdom.

“The virus is still passing through populations, albeit causing a lot less damage because of the high vaccination rates in vulnerable populations,” he said.

Cioe-Peña warned that another spike after the holiday break was likely in the United Kingdom, which could be seen in the United States during Thanksgiving.

“Any time we have seen lots of movement with kids or adults, we’ve seen COVID-19 spikes,” he told Healthline.

Schaffner made the same prediction:

“As we have seen it (in the United States), COVID-19 takes advantage of being moved about, being introduced to new populations, and being given new opportunities for a sprint. So, I would be more concerned, rather than more relaxed, about the impact of children being out of school, and now them being in new environments.”

However, for the United States, he was more optimistic.

“I think the holidays may bump up rates because of all this, but I don’t think we’ll have another large surge. It will be more local, confined. But there could be bumps up because of the holiday traveling and mixing,” Schaffner told Healthline.

Gandhi said that the rate of people over 12 years old who have received at least one dose of COVID-19 vaccines now stands at nearly 78 percent in the United States. With tens of millions of new COVID-19 cases recorded during the Delta surge, it could be likely that the United States is approaching the herd immunity level faster than the United Kingdom.

“Most experts say between 80 and 90 percent of the population needs immunity to bring Delta under control. [W]ith 34 million new shots and likely more than 30 million new infections, we could be up to over 85 percent seroprevalence now. With over 80 percent or even 90 percent to achieve control against Delta, we may be approaching this level now and may not see an increase in cases over the winter as a result,” she explained.

The United Kingdom’s latest surge is likely driven by school-age children socializing and mixing with other populations during their midterm holiday break.

The UK Health Security Agency (UKHSA) has since recommended that children take lateral flow (rapid antigen) tests before going back to school after the midterm break.

The lack of mask-wearing and containment measures are also playing a part in the spread of the coronavirus.

Waning immunity from vaccines and slow roll out for boosters, coupled with poor vaccination coverage in children, is also likely contributing to the recent surge.

A rebound in COVID-19 infections or a spike after midterms could be expected, and the United States may experience a similar situation around Thanksgiving, experts say.

However, as Gandhi points out, a future surge depends mainly on how much immunity is generated by vaccination and natural immunity from exposure to SARS-CoV-2.