Why the U.K. Saw a Big Drop in COVID-19 Cases as the U.S. Has a Surge

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The latest surge in the United Kingdom, fueled by the highly contagious Delta variant, is already dwindling.

In late July, the U.K. saw around 43,000 new infections on a daily basis. Now, that number has been halved, despite the easing of lockdowns and restrictions.

Infectious disease specialists suspect a number of factors are contributing to the rapid drop in cases, including the United Kingdom’s high vaccination rate, the fact that schools are out for the summer, and the warmer, more humid climate.

As the United States battles its own wave fueled by Delta, you might wonder if cases here will similarly rise then rapidly decline.

But health experts are skeptical. The United States is behind the United Kingdom in vaccinations, and states with especially low vaccination rates — like Louisiana — are hot spots seeing significant increases in COVID-19-related hospitalizations.

Unless the United States can rapidly boost vaccination rates across the country over the next few weeks, the current wave, which is predominantly impacting unvaccinated people, could last through the fall.

What to Know About the UK's Waves

Dr. Carl Fichtenbaum, an infectious disease specialist and professor in the division of infectious diseases at the University of Cincinnati College of Medicine, says the United Kingdom’s most recent wave was the fourth wave of infection it has seen since the start of the pandemic.

The first wave, which took place in April 2020, was relatively small, and the United Kingdom was able to flatten the curve.

A larger peak occurred in September 2020, which eventually receded, before an even larger wave unfolded in January 2021 when the highly contagious Alpha variant spread.

“That [third wave] fell dramatically, and they saw the same thing in July — it peaked and it fell dramatically,” Fichtenbaum said.

The Delta variant emerged in the United Kingdom in late April 2021 and was the dominant strain by May. This latest surge peaked on July 21 and now cases are free falling.

What’s encouraging about the United Kingdom’s latest wave, according to Fichtenbaum, is that while cases have soared, the number of people who have been hospitalized or admitted to the intensive care unit has been a fraction of what it was during the previous waves.

“That’s really reassuring that the level of vaccination and natural immunity is probably helping for people to be less sick during this particular wave of the Delta virus infections,” Fichtenbaum said.

What's Contributing to the UK's Drop in Cases? 

Dr. Bob Bollinger, a professor of infectious diseases at The Johns Hopkins University School of Medicine and founding member of emocha Health, suspects there’s a mix of contributing factors.

The United Kingdom now has high vaccination rates among adults: 88 percent of adults in the United Kingdom have been fully vaccinated against COVID-19, and 73 percent have received at least one dose.

While a high vaccination level means fewer people are susceptible to COVID-19, Bollinger said, “The drop-off seems too steep in the past week to be entirely due to herd immunity.”

There have also been high levels of masking, quarantining after exposures, social distancing, and reduced travel, Bollinger said.

Mask mandates were in place up until July 19.

Fichtenbaum noted that schools let out right before the United Kingdom’s peaks.

In the United Kingdom, children go to school through the end of December. About 3 weeks after kids stopped going to school, the third wave — this past winter — picked up. The fourth wave peaked on July 21, 2021, about a month after kids were let out for the summer on June 30, 2021.

“If the kids were still in school, it may have kept rising. There may have been more spread and more spread… but I think because they left school, there is less transmission going on among unprotected younger people who can then transmit it to older people in the community,” Fichtenbaum said.

Will We See the Same Declines in the US?

In the United States, 70 percent of adults have received one dose and 60 percent are fully vaccinated.

But in many states — Mississippi, Arkansas, Louisiana — the vaccination rate is much lower, which has caused these areas to become Delta hotspots.

“Given our much lower rates of vaccination and our much greater resistance to masking in the U.S., unfortunately, I do not expect that we will see such a sharp drop here,” Bollinger said.

There are millions of people in the United States who remain unvaccinated and therefore susceptible to contracting SARS-CoV-2.

As long as Delta is circulating, cases will likely continue to increase in vulnerable pockets before eventually dropping.

There is a certain level of natural immunity among people who contract and recover from COVID-19. These people have protection, but because natural immunity levels are not well understood, it’s not clear how much previously infected individuals contribute to waves peaking and falling.

“What worries me is we don’t have our vaccination rate up to 70 to 73 percent in every state like they do in the U.K.,” Fichtenbaum said.

In a few weeks, U.S. children are going back to school. With the Delta variant increasing, and without enough vaccinations or mitigation measures in places, Fichtenbaum expects we’ll see more hospitalizations in areas with low immunity levels.

More People Need to Get Vaccinated to Stop This & Future Waves

Ultimately, what happens next will likely largely depend on each area’s vaccination rate.

If we can get significantly more people in the United States vaccinated in the next few weeks, we may be able to see this wave peak in September or early October.

“If we can get up to 80 percent vaccination rate in most adults and get to 75 percent in school-aged children, I think we’ll be done with the pandemic,” Fichtenbaum said.

In response to Delta, the United States has seen an uptick in vaccinations across the country. But even if millions of people in the United States get vaccinated, it will still take about 6 weeks for them to achieve optimal protection, Bollinger said.

“If you want to see an immediate sharp drop like in the U.K., followed by sustained low levels of COVID-19 in the U.S., we would need to get everyone in the U.S. (vaccinated and unvaccinated) to wear a mask in high-risk settings for the next 2 months, while we also convince most of the unvaccinated to get their vaccine,” Bollinger said.

That’s going to be tough to achieve, as many people in the United States have grown tired of masks and several remain hesitant to the shots.

The Bottom Line

The latest surge in the United Kingdom, fueled by the highly contagious Delta variant, is already dwindling, which infectious disease experts attribute to the United Kingdom’s high vaccination rate, the fact that schools are out for the summer, and the warmer, more humid climate.

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