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Is the K number the new R number? What you need to know

Is the K number the new R number? What you need to know

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Just a few months ago, no one, aside from epidemiologists and their ilk, had heard of the R number. Now, thanks to the coronavirus, everyone has heard of it and most people can tell you that it’s the reproduction number, an indicator of whether the number of infected people is increasing or decreasing.

The R number is regularly referred to by governments around the world and by news anchors and their guests when discussing the pandemic. Yet no sooner had the public wrapped their head around one mathematical symbol than another cropped up. This time, the letter K. So what do we need to know about K and why has it suddenly become the focus of interest?

The R number represents the average number of people an infected person goes on to infect. If R is larger than one, the number of people with the disease is increasing. The target for control strategies, including lockdown, self-isolation and masks wearing, is to bring R below one and thereby reduce the number of people with the disease.

At the start of the coronavirus outbreak, R in the UK was around three. If every infected person infected exactly three people, the epidemic would have spread as in the figure below.

Epidemic spread with R=3; four generations are shown from the first person marked in red, through yellow, green and blue. Numbers indicate how many new infections originate from each case. Adam Kleczkowski

The average is not enough

The R mentioned in the daily press briefings represents an average of the whole country or region, involving millions of people. But its single value hides many differences between individuals and their impact on virus transmission.

Rather than assuming that every infected person and every contact they make follows the same pattern (as with the R number), scientists working on epidemic models allow for the number of new cases caused by each infected person to vary randomly.

Some people might have high viral loads or might simply cough more and hence spread the virus more effectively.

Many people, although ill and highly infectious, don’t show any symptoms. They might make many contacts without realising they pose a danger to others. An example from history is the infamous Mary Mallon (“Typhoid Mary”), a cook in New York City in the early 1900s. Although she carried typhoid bacteria, she didn’t show any symptoms and is believed to infect more than 50 people over seven years.

Mary Mallon in hospital (foreground). Wikimedia Commons

Super-spreaders

People also differ in the way they interact with others. For some, contacts might involve just the immediate family or a small group of colleagues at work or friends. The disease will then only have a chance to be transmitted to a few people. But if an infected person goes to choir practice, a football match or visits several pubs or nightclubs, the number of people who might catch the disease becomes large. Scientists call such massive and rapid outbreaks caused by one or a few infected individuals, super-spreading events, and their initiators are known as super-spreaders. In many cases, 80% of the new disease cases are caused by only 20% of such super-spreading individuals.

Dispersion parameter, K

Different pathogens will have different ways in which they spread and statisticians use K, the so-called dispersion parameter, to describe how variable the infection can be. For some diseases, the variation will not be large, as shown below.

Epidemic spread with a distribution of secondary cases with low dispersion and value of K much larger than 1. Adam Kleczkowski

Simply put, a low K value suggests that a small number of infected people are responsible for large amounts of disease transmission. For the 1918 influenza, the number K is thought to be around 1, and perhaps 40% of infected people might not pass on the virus to anybody else. But for diseases like Sars, Mers and COVID-19 with K as low as 0.1, this proportion rises to 70%. In contrast, large outbreaks will be initiated by only few super-spreaders, as shown below.

Epidemic spread with a distribution of secondary cases with high dispersion and value of K around or below 1. Adam Kleczkowski

Why is K so important?

There are two reasons why scientists are looking into the role of variability in controlling coronavirus transmission. First, super-spreading events are critical in the late stages of the epidemic when the virus is almost eradicated. Small values of K mean that one infected person can trigger many new cases in a very short time. If this happens, the epidemic can quickly rebound, even if locally eradicated.

Outbreaks in Seoul nightclubs in South Korea, meatpacking plants in the US, and coal mines in Poland show how damaging super-spreading events can be. So governments need to be diligent in identifying the risks associated with the reopening of industries and entertainment. A way to identify and track potential super-spreaders is fundamental to prevent future outbreaks.

But there is also a glimmer of hope. If indeed K is as low as 0.1, 70% of infected individuals fail to pass on the virus. As a result, most cases arriving from outside the country or region might recover without starting a new outbreak. It might, therefore, be easier to eradicate the disease and to maintain the disease-free status than suggested by the average reproductive number, R.

While R is not going to be replaced by K in the daily press briefing, both are needed to understand how COVID-19 spreads.

Adam Kleczkowski has received funding from BBSRC, NSF, Academy of Medical Sciences, and the Scottish Government.

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International

Memory in action: what the UK’s official COVID commemoration should look like

Memorialising a pandemic that is still underway is a challenge. Official commemoration needs to be about remembrance and preparedness.

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Whether an actual bereavement or a loss of experience, everyone has lost something to COVID. From early on in the pandemic, grassroots memorials sought to acknowledge this collective experience, including the national COVID memorial wall in London and the annual national day of reflection organised by the Marie Curie charity.

In September 2023, the UK Commission on COVID Commemoration released its final report on how a more official reckoning with the pandemic’s legacy should be shaped. It outlines ten recommendations.

The pandemic has affected people in vastly different ways. How governments, institutions and the wider public have responded has varied enormously, too. It is also still ongoing, which complicates things further.

New variants of the virus are on the rise. And nearly two million people in the UK alone continue to suffer with long COVID.

As immunologist Sheena Cruickshank put it recently, “it may feel like we should all be done with COVID-19, but sadly COVID-19 is not done with us”.

My research into memorial culture and modernism shows how the lack of a clear or coherent narrative for an event like a pandemic makes commemorating it that much harder. The official and cultural memory of the 1918 flu pandemic was subsumed into that of the first world war – and it remained largely unremembered, until COVID brought it back to public attention.

Nurses began erecting memorials early on in the first world war. Wellcome Collection Images, CC BY-NC-ND

Remembrance and preparedness

From October to December 2022, the UK Commission on Covid Commemoration held a six-week period of public consultation. It conducted surveys, garnering 5,000 responses. It also met with affected groups, including bereaved families and long-COVID sufferers, as well as groups that are sceptical about the illness and lockdown strategies.

The report is, to my mind, admirably well considered, sensitive to the difficulties of the task. It firmly establishes why memorialising all deaths that have occurred during the pandemic – COVID-related or otherwise – is necessary. This chimes with previous research that has found that COVID-related grief is particularly difficult and that public commemoration is necessary for social cohesion.

The 11 members of the commission suggest a range of commemorations, which will now be considered for implementation by the British government. These include an annual day of reflection on the first Sunday in March, a new symbol to represent the pandemic, the establishment of a commemoration trust to organise and promote these initiatives, along with a commemoration website and an online book of remembrance.

The commissioners suggest creating ten green spaces across the country, each boasting a sculpture created by local artists. They recommend preserving those grassroots initiatives already in place, including the national COVID memorial wall.

Finally, they propose various educational initiatives. These include teaching the history of the pandemic in schools and college and collating oral histories from a wide range of groups, to, as the report puts it, “serve as a historical record of this period of our time and as an educational tool for future generations”. A postdoctoral fellowship programme is suggested, too, to enable future researchers to work with policy makers on national preparedness for natural hazards.

Most of these recommendations are fairly standard commemorative gestures. The decision to create disparate pockets of remembrance across the UK rather than one large-scale memorial is expected, as there is no consensus or agreed-upon version of the pandemic.

The choice of green spaces is usefully open-ended in terms of meaning. The memorial sculptures destined for each will, doubtless, be similarly open-ended, in keeping with the minimalist, abstract and predominantly secular tendencies in modern contemporary memorials in the UK.

The report also proposes council funding for local commemorative spaces in existing parks or green spaces, not unlike the many community-led first world war memorials.

The COVID symbol the commission suggests is a zinnia flower. Associated with remembrance, this floral design has similarities to the poppy which has long symbolised the first world war.

Large-scale commemorative gestures have already been seen in other nations. Most notably, Joe Biden’s first act as US president was, during his inaugural address, to lead a moment of silence to remember the then 400,000 Americans lost to the pandemic.

By contrast, the UK public has felt left down by its government’s response. The news, that former prime minister Boris Johnson reportedly said, in autumn 2020, that he would rather see “bodies pile high” than impose a third lockdown on the UK, has left a bitter taste.

Johnson’s subsequent clandestine evening trip, in April 2021, to the COVID memorial wall, as well as public scandals such as Partygate, have further angered the public. Bereaved family groups such as COVID-19 Bereaved Families for Justice are understandably anxious to see that their loved ones are remembered officially as names and not as numbers.

The commission is eager to distinguish itself from the contentious COVID-19 Inquiry. This report is a useful corrective to the inadequacies of the British government in commemorating the pandemic to date.

Some may wonder if it is too early to commemorate a pandemic that isn’t yet over. After 1914, nurses began to create memorials as soon as the first deaths happened. The British government established the Imperial War Museum in 1917, while the war was still ongoing. I have shown how necessary these commemorative gestures were. They ensured that the dead were not forgotten.

Whether the government will now do is yet to be seen. In its insistence both on remembrance and on preparedness – for the next pandemic that, experts agree, will happen – this report is a good first step.

Alice Kelly received a British Academy Rising Star Engagement Award from 2017-19 for a seminar series entitled "Cultures and Commemorations of War."

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Government

Only 2% Of Americans Have Received New COVID Vaccine: CDC

Only 2% Of Americans Have Received New COVID Vaccine: CDC

Authored by Jack Phillips via The Epoch Times,

About 2 percent of all Americans…

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Only 2% Of Americans Have Received New COVID Vaccine: CDC

Authored by Jack Phillips via The Epoch Times,

About 2 percent of all Americans have received the updated COVID-19 booster shot after it was authorized and recommended by federal health officials several weeks ago, according to updated data provided by the Department of Health and Human Services (HHS).

More than 7 million Americans have taken the updated shot, which is authorized for people aged 6 months and older, said an HHS spokesman. That's approximately 2 percent of all Americans.

“COVID-19 vaccine distribution, which has shifted to the private market, is a lot different than it was last year when the government was distributing them," said a spokesperson for HHS about the vaccination data. It added that the agency is "directly with manufacturers and distributors to ensure that the vaccines are getting to" various locations.

The statement added that 91 percent of Americans aged 12 years and older "can access the vaccine within 5 miles of where they live," adding that 14 million updated boosters for COVID-19 have been shipped to pharmacies and other locations. The vaccine was approved about a month ago by the Food and Drug Administration (FDA) before it was recommended by the U.S. Centers for Disease Control and Prevention (CDC) shortly thereafter.

It came as some people reported that it's difficult to find doses of the new vaccines at local pharmacies and doctors. Jen Kates, a senior vice president at the Kaiser Family Foundation, said on X in September that her vaccine appointment was canceled due to a lack of supply.

The 7 million figure is up since Oct. 6 when Dr. Mandy Cohen, director of the CDC, told reporters that 4 million had received the new vaccines.

The HHS said Thursday that the latest updated vaccinate rate is about the same as the initial bivalent booster shot when it was rolled out in 2022. However, demand for the 2022 booster vaccine was similarly low, according to CDC data.

Data has shown that about 17 percent of the U.S. population got that previous updated shot, or around 56.5 million people.

The updated vaccines were meant to target the COVID-19 XBB.1.5 variant, which was spreading across the United States when companies like Moderna and Pfizer came up with the new version.

Observational data for the bivalent vaccines, or the previous versions, found weak initial effectiveness that quickly waned.

CDC officials made unsupported claims during the briefing, part of a trend for the agency. “These vaccines will prevent severe disease for COVID-19,” Dr. Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Disease, told reporters. There’s no evidence that’s true.

The only clinical study data for the new shots is from a study Moderna ran that included injecting 50 humans with the company’s updated formation. The result was a higher level of neutralizing antibodies. Officials believe antibodies protect against COVID-19.

Moderna did not provide any clinical efficacy estimates for infection, severe disease, or death. Pfizer said it was running a trial but has not reported any results.

Novavax’s vaccine was authorized later without any new trial data, as CDC officials have said they recommend that shot. Unlike the Moderna and Pfizer vaccines, Novavax doesn't use mRNA technology and is protein-based.

Hospitalizations Down

Despite the recent push for the latest vaccines, data provided by the CDC shows that hospitalizations for COVID-19 have been down for about three consecutive weeks.

For the ending Sept. 30, the hospitalization rate is down by 6 percent, while emergency department visits are down by 14.5 percent and COVID-19 cases are down 1.2 percent, the figures show. Deaths are up 3.8 percent, although health officials have previously said that deaths generally lag behind hospitalizations and case numbers.

In July, COVID-19 hospitalizations had been increasing for several consecutive weeks. CDC historical data suggest that deaths have been relatively low compared with previous years.

But with the release of the Sept. 30 data, hospitalizations have dropped for multiple consecutive weeks.

Dr. Shira Doron, chief infection control officer for Tufts Medicine, told ABC News that that the recent “upswing is not a surge; it’s not even a wave.”

The doctor added: “What we’re seeing is a very gradual and small upward trajectory of cases and hospitalizations, without deaths really going along, which is great news.”

The CDC on Oct. 6 released a report that attempted to push older Americans to get the newest vaccines by saying that COVID-19 is still a "public health threat," namely for people aged 65 and older. The majority of hospitalizations, it said, is occurring among that older demographic, according to the paper.

In the meantime, a handful of hospitals in California, New York state, Massachusetts, and New Jersey have re-implemented mandatory masking—at least for staff.

Several Northern California counties issued a mask mandate for all health care staff starting next month and ending in late April 2024. They include Contra Costa, Sonoma, Alameda, and San Mateo counties. Officials in the Southern California county of San Luis Obispo also issued a vaccine-or-mask mandate earlier this month.

Tyler Durden Mon, 10/16/2023 - 12:20

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Spread & Containment

Worsening Treasury Liquidity Keeping Fixed-Income Vol Elevated

Worsening Treasury Liquidity Keeping Fixed-Income Vol Elevated

Authored by Simon White, Bloomberg macro strategist,

Poor liquidity in the…

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Worsening Treasury Liquidity Keeping Fixed-Income Vol Elevated

Authored by Simon White, Bloomberg macro strategist,

Poor liquidity in the Treasury market is contributing to a rise in implied and realized fixed-income volatility. A re-increase in inflation volatility means this dynamic is likely to persist.

Despite being one of the deepest markets in the world, the market for Treasuries has seen liquidity deteriorate in the years since the pandemic. On several measures – bid/offer spread, order-book depth, price impact of a trade – the Treasury market has shown marked signs of a decline in liquidity in recent years.

Bloomberg’s US Treasury Liquidity Index measures liquidity by comparing where yields are to where they “should” be based off a fitted curve. The greater the average of the yield errors across the curve, the worse liquidity is likely to be.

As the chart below shows, the Liquidity Index infers liquidity has markedly weakened over the last two years, and after showing an improvement over the last six months, it has started to worsen again.

Fixed-income volatility, using the MOVE index, intuitively rises and falls as liquidity worsens and improves respectively.

Bond volatility has been notably higher in this cycle than other assets’ volatility, such as equities and FX. Indeed, the recent rise in the MOVE index, i.e. implied volatility, has taken it to a level above realized volatility it has rarely exceeded in the last 30-plus years.

The immediate catalyst for the rise in bond volatility has been the Federal Reserve’s rate-hiking cycle. But this was itself triggered by the rise in inflation. It is the inherent increase in uncertainty that goes with elevated inflation that is the ultimate source of rising volatility.

Higher inflation volatility goes hand in hand with higher market volatility, especially in rates and fixed-income markets. Inflation is very likely to be persistent, and soon to begin re-accelerating. Inflation volatility has moderated somewhat from its recent highs, but is picking up again.

As long as inflation volatility remains elevated, bond vol will remain likewise. This is even more so the case as the yield curve continues to rise, with steeper curves an inherent source of yield volatility.

Tyler Durden Mon, 10/16/2023 - 08:45

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