Why do Covid cases rise dramatically with the spread of vaccination?

Kendall Bolden, 15, holds her aunt’s hand as she receives a coronavirus vaccination on August 14, 2021 in New Orleans, Louisiana.

Mario Tama | Getty Images

LONDON – Looking at the Covid case data in the US, UK and the rest of Europe, you’d be forgiven for thinking that despite 18 months of global health crisis and advanced vaccinations, we’re just as badly off as we’ve ever been.

To be sure, the number of Covid cases being recorded per day in the West is still high, rather similar to previous peaks at various points, or Covid waves, during the pandemic.

The current 7-day moving average of daily new cases is 153,246, an increase of 4.9% over the previous 7-day moving average (146,087). The current 7-day moving average is 123.6% higher than the value observed about a year ago, According to data collected by the Centers for Disease Control and Prevention (CDC). In total, more than 40 million Covid cases have been counted in the United States since the pandemic began.

Case rates in the UK are also still high. As of September 6, the seven-day average of daily new cases was about 39,000, and the number of daily cases remained high as the week progressed; Nearly 40 thousand new cases were reported on Wednesday, and about 38 thousand cases were recorded on Thursday, Government data showed.

In the EU + European Economic Area (a total of 30 countries), in the seven days to September 5, 405,774 new cases were registered, According to the European Center for Disease Prevention and Control, with Ireland, France, Sweden, Portugal, Greece and Bulgaria among the countries reporting the highest number of new cases per 100,000 population.

The large numbers of cases are still attributed to the spread of the highly contagious delta variant, which usurped earlier variants that were themselves more contagious than the original strain of Covid-19.

However, the rise in cases has accompanied the advancement of vaccination programs in the West with the majority of adults in both the United States and Europe now fully vaccinated.

In the United States, 62.4% of all people over the age of 12 are fully vaccinated, Centers for Disease Control and Prevention (CDC) data shows, while more than 82% of those over the age of 65 are fully protected. in the UK, 80.4% of the population over the age of 16 has been fully vaccinated In the EU/EEA, 70.4% of adults received two doses of the coronavirus vaccine, ECDC data appears.

Crucially, the number of hospitalizations and deaths associated with the high number of cases has remained lower (and in some countries, much lower) than at earlier points in the epidemic when vaccination rates were much lower, proving that coronavirus vaccines in use in the West are greatly reducing The chances of severe infection, hospitalization and death. Hospitalizations in the United States remain high, according to data from Our World in Data.

However, none of the vaccines used in the United States or Europe are 100% effective, which means that some vaccinated people will develop Covid (so-called “breakthroughs”) and a few will become ill. The dominant delta variant also reduced the efficacy of the offered vaccines and Some new studies show that the immunity provided by the shots diminishes over time.

Why are cases so high?

CNBC asked Britain-based epidemiologists why cases are still rising given the relatively high vaccination rates in the West.

“The delta variant is highly contagious and that explains why the number of cases continues to rise now that we mingle more freely because most restrictions have been relaxed,” Andrew Friedman, a reader in infectious diseases at Cardiff University School of Medicine, told CNBC Thursday. .

He noted that “the people who contract Covid now are a mixture of unvaccinated, partially vaccinated and double vaccinated people. A large proportion of new infections occur in (unvaccinated) children and adolescents.”

“We know that vaccines are only partially effective in preventing people from picking up the delta variant, but they are more effective in protecting against severe illness, hospitalization, and death. Fully vaccinated individuals often only have mild symptoms if they contract them, although a small minority, especially The elderly and the more frail, the more serious diseases they still suffer.”

In the UK, the latest data from the ZOE Covid Study, which tracks Covid symptoms and infections in the community using data from around 1 million people each week, indicates that in the fully vaccinated population, there are currently 17,674 new cases of daily symptoms in the UK.

And she indicated, in her latest research published on Thursday, that “the cases in this group have been on a steady rise but are now stabilizing, with last week’s number reaching 17,342.”

Meanwhile, new Covid cases are highest among those aged 0-18 and 18-35, many of whom have only been partially vaccinated (two doses of a Covid shot needed to achieve maximum protection), or are not vaccinated.

Similar data relates to the United States and the rest of Europe over the past month: CDC data shows that the largest number of cases were counted among 16- to 17-year-olds (although age groups 12-49 experienced All are a sharp increase in cases.). In the EU/EEA The largest number of cases is among the 25-49 age group followed by the 15-24 age group and the increasing number of cases is among children aged 5 to 14 years.

Epidemiologists and public health experts have long expressed the view that Covid-19 is just something we have to get used to, That the virus will become endemic It cannot be eradicated now.

Pursuing the so-called “zero Covid” strategy (which aims to eliminate all cases of Covid) is considered a hopeless issue by most countries, although Australia and New Zealand have pursued such a strategy. Australia announced at the end of August that it would abandon such a policy, however, given the prevalence of the highly contagious delta variant. New Zealand is keeping to its strategy, for now.

Danny Altman, professor of immunology at Imperial College London, explained to CNBC that societies need to assess how much they will tolerate the virus.

“We’ve always said, and still maintain, that vaccines are amazing and provide massive levels of protective neutralizing antibodies,” he told CNBC Thursday. Even if clinical studies show that the delta variant reduces the effectiveness of vaccines, Altman noted that “there is a good deal of protective leeway most people should be safe with.”

“In a sense, that’s how we’ve seen it happen — with the delta variant and without vaccination, we’d now be at several thousand deaths per day, but we’re ‘only’ a few hundred, so there’s appreciable mitigation of serious illness.”

“However, our protection against Delta seems less robust than we expected when you consider that in the UK there are about 40,000 cases per day including many of these breaches… [and] People became significantly fine but not hospitalized,” he said, noting that data from Israel on booster doses showed that additional scones can re-boost antibody levels and combat breakouts.

A lot of the controversy surrounding Covid currently, Altman said, “goes back to the policy/philosophy debate about what we’re trying to achieve right now.”

“The extremes of the argument, either that, at least until we see what happens in the fall/winter, we have achieved our goal as the relatively high vaccine rollout means hospitals can adapt…or the other view is that we will never live a normal life unless we strive Strive for a Covid-free strategy, which will need to include vaccination in our schools to stop its spread there.”

Altman said those calling for a zero Covid strategy included people who thought we were “staying forever slow for more cases than ever, until we allow the use of a more resistant variant to really spoil us.”


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