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The K factor: why it matters where we are infected with the coronavirus

The way the coronavirus is spread is not always the same. Not all positive cases infect the same number of people – instead, most contagions appear to be linked to specific events and superspreaders. Most infections are caused by a few people, and many positive cases never transmit the disease. This is both good and bad news. On the one hand, it means that if these super-spreading events can be controlled, the number of cases can be reduced without having to lock down the entire country. But on the other, it requires exhaustive contact tracing to connect infected people to where they caught the disease. In Spain, the large majority of cases have not been able to be linked to any known outbreak. 

During the first wave of the coronavirus pandemic, there was a lot of talk about the figure R, or the reproduction number, which represents the average number of people that one infected person will pass a virus on to. This number presents a typical and homogenous pattern for transmission: if one positive case infects three others, these three will infect another three and so on and so forth. This represents, more or less, the transmission of the flu.

But there is evidence that coronavirus contagions don’t happen this way, but are rather dictated by what happens in groups of people. Research from the London School of Hygiene & Tropical Medicine and a recent study published in the science journal Nature indicate that a few events (such as a choir rehearsal or a meeting in a poorly ventilated room) and a few infected people (who perhaps have a higher viral load or a very active social life) are responsible for the large majority of contagions. It is estimated that 80% of transmissions are caused by between 10% and 20% of positive cases. For example, if five people had the coronavirus, two of them would not infect anyone, the other two might spread it to one person each and the fifth person would infect eight others.

To determine if the rate of infection is one type or another, scientists use another parameter: the K factor, the measure of its dispersion. The lower this number is, the higher the number of contagions from large gatherings. The K factor of Covid-19 could be as low as 0.1, according to some research, which is lower than that of SARS (0.16) and MERS (0.25), and far below the figure for the flu (1).

Although there continues to be debate about coronavirus transmission, there is a growing number of studies and indicators that highlight the importance of clusters – the group of people who are the source of contagions. This has consequences for how we fight the epidemic: we must have a better understanding of outbreaks and consider new ways of tracking cases, two things that Spain is not doing.

We must have a better understanding of clusters so that we can take surgical measures to slow the spread. If we discover that there are places and circumstances where outbreaks are likely, we can introduce measures to prevent them. Japan is one of the countries that has centered its strategy on the careful identification of each cluster. Although Japan has seen ups and downs in its epidemiological curve, its worst moment, when the number of cases peaked, is similar to the most benign one in Spain. The number of deaths in Japan per 100,000 inhabitants is 50 times lower than the figure in Spain.

During the first wave, a member of Japan’s coronavirus cluster task force told The Atlantic that while Japan “looking at a forest and trying to find the clusters, not the trees,” “the Western world was getting distracted by the trees, and got lost among them.” In Japan, authorities focused on identifying and avoiding clusters, which usually happened in enclosed spaces with large numbers of people. South Korea followed the same strategy: 66% of cases reported until July were linked to an identified cluster, 10% to individual case-based contacts and 24% were unidentified. In Spain, the figures are reversed: contact tracing has only been able to link 12% of cases to specific events

The problem of not having a good contact tracing system is that it makes it impossible to know where outbreaks are happening. “With the tracking capacity of many regions, the most that can be done is to confirm that there is transmission in homes without qualifying the relative importance of each source of transmission,” says Miguel Hernán, a professor of epidemiology at Harvard University. He believes there has been a lack of political will to support contact tracing, with authorities not understanding that public health and the economy go hand in hand. “A good tracking system is the best economic investment, so that you can know what activities are more or less safe and apply more selective closures,” he tells EL PAÍS.

Should we be doing backward contact tracing? Going to the source of an outbreak is a way to cut the chain of transmission. Right now, contact tracing works forward: if I test positive, a tracker will look for people among my contacts who may have been infected when I was experiencing symptoms. But it is likely – as studies suggest – that I have not infected anyone. So how should a disease that is spread by clusters be tracked? One idea is to do it backward: to look at where I contacted the virus. Because this is likely to have been a super-spreading event. “The best thing would be to isolate those who form the cluster as a preventive measure and do more detailed and backward tracking,” explains Yamir Moreno, from Zaragoza University, who has been studying the impact of these events on the spread of the coronavirus in Spain. “It would allow you to see the ramifications in each transmission chain that you don’t see with traditional tracking,” he adds.

With conventional contact tracing, the infected person under review has a low likelihood of transmitting the virus. But the person who infected them probably belongs to the 10% to 20% responsible for 80% of all cases. That person could have caused more infections. “Trying to find the source of the infection widens the possibility of identifying a cluster,” explains Mirjam Kretzschmar, professor of infectious disease dynamics at Utrecht University. “In backward tracking, you must identify who the confirmed case has been in contact with up to two weeks before they tested positive,” she adds. The problem with this is that it requires fast action. Her team has estimated that if more than three days pass between the onset of symptoms and the test and isolation, contact tracking produces few results. This is especially true for backward contact tracing: those who have been infected by the superspreader will be more difficult to locate and will have had ample opportunity to spread the disease.

Backward contact tracing is doubly challenging for Spain. Right now it would seem that the country is not even doing conventional tracking properly: the average number of contacts identified per each positive case has fallen to two, according to official data from the Health Ministry. In other words, often it does not even cover members of the same household. “The alert system was not ready for such a high volume of cases,” says Ángel Garay Moya, a doctor and specialist epidemiologist in Castellón. Public health services regret the lack of permanent resources. What’s more, contact tracking in Spain often falls to primary healthcare doctors, who are also overwhelmed.

Given these circumstances, some experts have all but ruled out backward contact tracing, which as well as being more demanding, also has fewer proven results. “It’s possible to manage it with a few cases, like the 60 daily ones at the start of the second wave, but not with community transmission, when there are more than 200 every day,” says Garay Moya.

Miguel Hernán also regrets that Spain does not have greater contact tracing capacity. “It is a shame because tracking chains of transmission to their source is one of our best weapons, if it is done quickly.” Before the tracking system collapsed in Spain, the links found between cases and outbreaks did reveal certain patterns. Over the summer in Valencia, a series of connected outbreaks led to 100 coronavirus cases among the Colombian community in the eastern region. Further analysis revealed that all of the outbreaks were related to celebrations, in dance halls and private parties, for Colombia’s Independence Day.

The K factor is behind some of the mysteries of the pandemic. Transmissions by clusters can help explain why some places were hit by the coronavirus before others. This could partly be down to chance: population density, cultural customs and climate are factors that are usually mentioned. But several studies (including ones by Adam Kurcharsi, the Bern University in Switzerland and one published in Nature) point to super-spreading events. Many countries had imported cases, i.e. people who contracted the virus abroad, but these individuals were almost always sparks that died out before spreading the disease. That is until one or several of these sparks lit up a cluster, perhaps just out of bad luck: an infected person goes to a funeral, a market, a call center, a senior residence or a party in an enclosed space. The evolution of first wave of the epidemic may have depended on whether one or none of these super-spreading events happened.

This dynamic could explain, for example, why coronavirus cases spiked in Italy before they did in Germany, or why the first cases in Spain and France did not cause any outbreaks.

The good news. There is an upside to a virus that spreads via clusters: if only a few events are responsible for many contagions, the epidemic can be controlled with specific measures that don’t affect everything, at least in theory. If there are situations where the risk of catching the virus is low, and we know what they are, we will be able to salvage parts of normal life without putting ourselves in danger.

English version by Melissa Kitson.

Arnold Schwarzenegger’s son tells him ‘please don’t work out today’ after actor undergoes heart surgery

Arnold Schwarzenegger is recovering after undergoing heart surgery.

The Terminator star told fans he feels “fantastic” after being given a new aortic valve.

The 73-year-old was given a new pulmonary valve in 2018 to replace the one he received in 1997, due to a congenital heart defect.

In a post to social media, Schwarzenegger thanked doctors at the Cleveland Clinic in Ohio, and said he had been enjoying the local sights since his operation.

Photos showed him in a hospital bed with his thumbs up, and other pictures of him exploring the area.

“Thanks to the team at the Cleveland Clinic, I have a new aortic valve to go along with my new pulmonary valve from my last surgery,” he wrote.

Arnold Schwarzenegger is recovering after undergoing heart surgery.

The Terminator star told fans he feels “fantastic” after being given a new aortic valve.

The 73-year-old was given a new pulmonary valve in 2018 to replace the one he received in 1997, due to a congenital heart defect.

In a post to social media, Schwarzenegger thanked doctors at the Cleveland Clinic in Ohio, and said he had been enjoying the local sights since his operation.

Photos showed him in a hospital bed with his thumbs up, and other pictures of him exploring the area.

“Thanks to the team at the Cleveland Clinic, I have a new aortic valve to go along with my new pulmonary valve from my last surgery,” he wrote.

“I feel fantastic and have already been walking the streets of Cleveland enjoying your amazing statues. Thank you to every doc and nurse on my team!

Schwarzenegger’s son Patrick commented on the Instagram post, joking: “PLEASE DON’T GO WORK OUT TODAY.”

Reference:Independent:   Roisin O'Connor: 3 hrs ago

Racial discrimination widespread in NHS job offers, says report

Doctors from black, Asian and minority ethnic backgrounds have been hindered in their search for senior roles because of widespread “racial discrimination” in the NHS, according to a report from the Royal College of Physicians.

The RCP, which represents 30,000 of the UK’s hospital doctors, found that ingrained “bias” in the NHS made it much harder for BAME doctors to become a consultant compared with their white counterparts.

“It is clear from the results of this survey that racial discrimination is still a major issue within the NHS,” said Dr Andrew Goddard, the RCP’s president. “It’s a travesty that any healthcare appointment would be based on anything other than ability.”

Minority ethnic hospital doctors suffered a double disadvantage in their quest to progress their medical careers by being promoted from a trainee doctor to a consultant, it said.

White doctors applied for fewer posts but were more likely to be shortlisted and offered a job, the RCP found. BAME doctors had less chance of being shortlisted for an interview for a consultant post after their first application, and they were also much less likely to be offered a post after an interview.

The report, which is based on a survey of 399 newly qualified consultants in 2019, said: “White respondents had a 98% chance of being shortlisted after their first application, compared with 91% of black, Asian and minority ethnic respondents.

“The big difference was in likelihood of being offered a post for the first time round: 29% of white respondents were offered a post after being shortlisted for the first time compared with just 12% of BAME respondents.”

The RCP examined eight years of data on the experience of doctors, typically in their 30s, who had recently gained their certificate of completion of training, which means they can then apply for their first post as a consultant in a hospital.

Its analysis uncovered “consistent evidence of trainees from BAME backgrounds being less successful at consultant interview. This is despite adjustment for potential confounding factors. The results … suggest there is bias that needs to be acted on.”

Roger Kline, a research fellow at Middlesex University and an expert in racial discrimination in the NHS, said the findings proved BAME medics suffered from “systemic discrimination”.

“These findings are appalling and confirm what many doctors across all medical specialities have long suspected has been occurring.

“These patterns of discrimination are really hard for individual doctors to challenge so the medical profession as a whole, and their employers, need to finally accept systemic discrimination exists and take decisive action.”

Related: NHS blood unit systemically racist, internal report finds

The RCP found that BAME doctors have more chance of being shortlisted after their first application than they did when it first sounded the alarm about inequity in career progression in 2018. That prompted NHS England to include those findings in its medical workforce race equality standard, which is meant to eradicate bias on racial grounds.

Research in 2018 found that black doctors in the NHS in England are paid almost £10,000 a year less than white colleagues, while the gap for black nurses is £2,700.

Charlie Massey, the chief executive of the General Medical Council, which regulates the profession, said: “All doctors should have the same opportunities to fulfil their potential and it is unacceptable if there are biases that prevent this from happening.”

Joan Saddler, the director of partnerships and equality at the NHS Confederation, which represents health service bosses, said: “Leaders are clear that there should be no room for discrimination of any kind within the NHS … The NHS is making some progress on this issue but, clearly, there is much further to go.”

The NHS in England has set itself a target of ensuring that by 2025 at least 19% of those at every pay level are of BAME origin. Overall BAME people make up 17.5% of its staff.

A spokesperson for the NHS in England said: “It is unacceptable for anyone to be treated unfairly because of their race or any other protected characteristic.

“The NHS belongs to us all, and as part of the People Plan, NHS employers are committed to increasing black, Asian and minority ethnic representation across their leadership teams as well as eliminating discrimination and inequality.”   

Reference: The Guardian: Denis Campbell Health policy editor: 12 hrs ago

Experimental COVID-19 vaccine is made available to Chinese residents 

Officials in an eastern Chinese city is offering its residents an experimental coronavirus vaccine for £46 per person - despite the fact that its effects remain unproven.

Key workers and those at high risk from COVID-19 would be among the first to receive the jabs, said the health authority in the city of Jiaxing, Zhejiang province. 

Other 'volunteers' aged between 18 and 59 with 'urgent need for vaccination' may also apply to receive the vaccine developed by the state-owned drug firm Sinovac Biotech, a statement said. 

China has been inoculating essential workers with COVID-19 vaccine candidates under an emergency use programme launched in July. 

But this is the first time the Chinese government has publicly made such vaccine available to ordinary citizens.

It comes as a Beijing official has previously announced that a coronavirus vaccine could be ready to use for the general public in less than three weeks.

But some residents in Jiaxing have now been offered with a double-dose experimental coronavirus vaccine that costs 400 yuan (£46), according to a statement released by the city's centre for disease control and prevention on Thursday.  

The vaccine candidate called CoronaVac, developed by Sinovac Biotech, will be provided to people, aged between 18 and 59, who have 'urgent need for vaccination'.

Residents will be given two shots, which are administered up to 28 days apart, after signing an inoculation agreement as the vaccine's effects have yet to be proven.

'As it has not officially been registered for the market, this type of vaccine is only approved for urgent use', the notice added.

But the officials did not specify how many people would receive the experimental vaccine or when the programme would start. 

A CDC staff member told state media the Global Times: 'Details of when and how the vaccines will be distributed to [the vaccination sites] across the city are still being worked out.'

The vaccine from Sinovac Biotech is also in late stage trials in Brazil, Indonesia and Turkey, and the company has said that an interim analysis of Phase 3 trial data could come as early as November.

Bio Farma, a state-owned firm in Indonesia which has reached a deal for at least 40 million doses from Sinovac, said this week the vaccine will cost around 200,000 rupiah (£10.48) per dose when it becomes available in the southeast Asian country.  

Chinese authorities have yet to release pricing details for potential COVID-19 vaccines. But Beijing has said that while reasonable profits for companies are permitted, COVID-19 vaccines should be priced close to cost.

China has four of the world's eight vaccines that are in the third phase of trials, typically the last step ahead of regulatory approval, as countries race to stub out the virus and reboot battered economies.

At least three of those have already been offered to hundreds of thousands of essential workers under an emergency scheme launched in July with no reported adverse effects, according to officials.

A unit of state pharmaceutical giant China National Pharmaceutical Group (Sinopharm) and US-listed Sinovac Biotech are developing the three vaccines under the state's emergency use programme. 

During an interview with state broadcaster CCTV in September, an official with the Chinese Center for Disease Control and Prevention (CDC) said that a coronavirus vaccine could be ready for Chinese citizens as early as November. 

'It would be about November or December,' Wu Guizhen, CDC chief biosafety expert, told the state media. 'Ordinary people can be vaccinated with the vaccine, because according to its phase III clinical results, the current progress is proceeding very smoothly.'

But the World Health Organization has warned that widespread immunisation against COVID-19 may not be on the cards until the middle of next year.

Tedros Adhanom Ghebreyesus, the head of the World Health Organization, said last month that the U.N. health agency will not recommend any COVID-19 vaccine before it is proved safe and effective.

His comment comes after Russia and China have started using their experimental vaccines before large studies have finished and other countries have proposed streamlining authorisation procedures.