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A massive testing scheme that will take coronavirus samples from 100,000 people will have a ‘big impact’ on when and how the UK comes out of the blockade.
In a national effort to determine how fast the virus is spreading in Britain, scientists have embarked on an attempt to assess tens of thousands of people and begin long-term surveillance of COVID-19 cases and the local outbreaks.
Doing so will help them calculate the virus’s replication number, known as the R value, which will then influence when blocking measures can begin to rise.
Prime Minister Boris Johnson confirmed yesterday that the R is now less than 1, which means that the virus is spreading more slowly than one by one and that the outbreak is on its way to reaching a natural end.
At the start of the outbreak in the UK, the R rate had been between 2.4 and 4, scientists say, but the dramatic home stay measures that were implemented on March 23 have cut it by at least two-thirds. .
The virus cannot survive if the R remains below one, and the government must now escalate its testing and surveillance to ensure that it is never allowed to exceed that number again.
Carrying out hundreds of thousands of tests on people across the country, regardless of whether they might have COVID-19, will now be vital to moving forward.
Lord Ara Darzi, director of the Institute for Global Health Innovation at Imperial College London, said that a plan to screen 100,000 people in 315 different areas of the country is now “working” and early results are expected within “a couple weeks. ” ‘.
This will be combined with routine tests on a randomly selected group of at least 25,000 people who will undergo regular swab tests to be analyzed by the University of Oxford over the next year so that scientists can trace the virus over time.
The Imperial College COVID-19 Response Team, which has been advising the Government, estimated in March that the global average R0 for the coronavirus was 3.87. As social distancing and blocking took effect, that number has now plummeted below 1, potentially as low as 0.5, meaning the virus will naturally go extinct if this continues.
Lord Darzi said on BBC Radio 4 this morning that the mass testing project would provide a “snapshot” of the current situation in the UK that could then be traced back.
He said: “ We will test 100,000 people at 315 randomly selected local authorities, and the snapshot will give us not only the R-value at the national level but also at the local community level, which is also critical.
‘We are operational, we have shipped almost 2,000 and it will take a couple of weeks to get them out and back.
“And obviously we have to analyze them and inform policy makers because this will have a significant impact in terms of facilitating the blockade.”
“There is another study underway at Oxford in 20,000 homes that will be repeat testing … so the combination of these two studies will be very informative in terms of moving on to the next phase.”
Prime Minister Boris Johnson put the R value at the heart of Britain’s coronavirus battle at his Downing Street press conference yesterday when he revealed the Government’s dedication to keeping it below 1.
It is currently estimated to be between 0.6 and 0.9, which means that every 10 people who become infected with the virus can be expected to transmit it to another six or nine.
This means that as long as the breeding number can be kept below 1, the outbreak will eventually run out of way and naturally come to an end.
However, lifting the blockade measures will increase it and politicians are now under pressure to juggle the damage caused by an economic shutdown with the damage that would be caused by a second outbreak and a second blockade.
Because so few people have had the disease and developed immunity, it is vital that the number of people currently infected decrease as much as possible before the closure is lifted, to prevent those patients from triggering another outbreak.
Dr. Kit Yates, Senior Lecturer in Mathematical Biology at the University of Bath and author of The Maths of Life and Death, told MailOnline: ‘The reason we are waiting to close the closure for so long is because we want to reduce the cases at a very low level and the fastest way to do this is to keep R as low as possible.
He added: ‘Until we really go through the experiment of lifting the different constraints, we really won’t know the effect on R.
“Much caution can be expected in the measures that the government is beginning to relax. Expect it to be conservative initially.
As COVID-19 surveillance intensifies, the Government is now moving towards four main population testing schemes.
Imperial College London will oversee the two-part REACT program (Real-time Assessment of Community Broadcast).
The first part of this will be the 100,000 tests of random people in 315 different areas of the UK, to see how many of them are currently infected; this is the scheme to which Lord Darzi referred.
The second part will be a deployment of home antibody tests, which can determine if people have already had the disease and have recovered. These will be given to 300 people for an initial test and then spread to 10,000 people, and then 100,000 if successful.
Antibody tests will create a picture of how many people have already had the virus and may have immunity to it, which means they won’t detect it again, at least in the short term.
These two test phases will run alongside two other long-term programs announced last week as part of the government’s ‘test, track and trace’ plan.
At least 25,000 people will be enrolled in a scheme where swab tests will be done regularly at monthly intervals to see if they are currently infected.
This will continue over the next year and will expand to include 300,000 people if deemed useful.
And more antibody tests will be conducted at 1,000 homes across the country where people will give blood samples for testing to assess whether they have developed immunity to the virus.
Dr. Yates of the University of Bath added: ‘Looking at how case numbers are changing can give us an idea of the current value of R.
‘If we see that the cases are decreasing, this suggests that R is less than one.
‘Modelers can adapt their models to case data (or perhaps more reliable deaths) to reverse engineer the R value that best fits. Hospital admission data can also give us an idea and may be a little more reliable than test figures. ”
How Britain’s R number plummeted when the blockade was introduced and what it means to get out the other side
Prime Minister Boris Johnson last night put detailed science at the heart of Britain’s coronavirus crisis and said the state of the blockade now depends on the replication number of the virus, known as R.
Observing the number of new patients and the rate at which it increases or decreases will be the best way for officials to monitor how fast the virus is spreading, which in turn will guide the risks the government believes it can take to lift the lock.
Data showing Britain’s R-value will shape everyone’s life in the UK in the coming weeks and months, and MailOnline here explains how:
What is the R number?
Each infectious disease receives a reproduction number, which is known as R0, which is pronounced ‘R nothing’, or simply R.
It is a value that represents how many people an ill person will infect, on average.
Most epidemiologists, scientists who track disease outbreaks, believe that the SARS-CoV-2 virus, which causes COVID-19, has an R-value of around 3.
But some experts analyzing outbreaks around the world have estimated that it could be closer to the 6.6 mark.
Estimates of R vary because the actual size of the pandemic remains a mystery, and how fast the virus spreads depends on the environment.
As an outbreak progresses, R is simply known as R, which means the effective rate of infection: nothing works under the premise that no one in the population is protected, which becomes obsolete as more people recover .
How does the reproductive rate compare to other infections?
SARS-CoV-2 is believed to be three times more contagious than the coronavirus that causes MERS (0.3 – 0.8).
Measles is one of the most contagious infectious diseases and has an R0 value of between 12 and 18 if not controlled. Widespread vaccination keeps it suppressed in most developed countries.
The R0 of chickenpox is estimated to be between 10 and 12, but this is controlled in the UK by herd immunity. So many people catch it as children and become immune to reinfection that cannot spread among adults.
Seasonal flu has an R-value of around 1.5 but it mutates so often (there are often one or more new strains each year) that people cannot develop full immunity against it. Recovering from a flu strain does not protect someone from others.
Ebola has an R0 of between 1.4 and 1.8; This is low, but so far it has only spread in countries with poor health services, and its extremely high mortality rate (50%) makes it a threat.
Mumps has an R0 of between 10 and 12, making it highly infectious, but the measles vaccine (MMR) protects most people in Britain from contracting it.
The R0 for whooping cough, medically known as pertussis, is estimated at 5.5. The NHS urges mothers to receive the pertussis vaccine during pregnancy because they can naturally transmit immunity to their baby.
How is it calculated? And can scientists be sure of the number?
R is not a set number and scientists calculate it by studying how fast the virus spreads in its perfect environment and also in society.
While the biology of the virus and how it spreads, whether through cough or blood, will have some influence, but human behavior is a bigger factor.
Tracking the increase in the number of new cases and the speed with which the number of patients doubles are two of the best ways to estimate R, according to the professor of mathematical biology at the University of Bath and author of Maths of Life. and death, Dr. Kit Yates.
He told MailOnline: ‘Most modelers will give ranges of uncertainty with their estimates suggesting that R could be as high or low as that.
‘R0 is not a fundamental property of the virus. It will change depending on the community through which the disease is passing.
‘[It] it depends on three factors: transmissibility (how easily the disease passes between people); the infectious period (the longer it is, the more likely it is that an infectious person will transmit the disease); and the population through which the disease is passing.
“The more people there are and the more densely populated, the easier it will be to spread the disease, so we cannot take the measured R0 in one country and use it in another.”
Dr Jennifer Cole, a biological anthropologist at Royal Holloway University in London, said: “It is incredibly difficult to calculate [the R0] without doing it in retrospect.
He explained that detailed data can show how fast the virus has spread, but they are more accurate when looking back in time, not today.
“At the moment we don’t have exact numbers, but we have a rough idea,” added Dr. Cole.
“As long as you can say that R0 is between one and two, or between three and four, that’s broad enough to make the decisions you need about social distancing.”
Did Britain’s R number plummet when the blockade was introduced?
The COVID-19 response team at Imperial College London estimated the R0 value for coronavirus to be 2.4 in the UK before the blockade began.
This meant that, before Prime Minister Boris Johnson ordered the national shutdown on March 23, every 10 people who contracted the virus would infect 24 others.
But scientists have since calculated that the rate has dropped below 1, meaning the crisis will subside if the situation remains the same.
Researchers at the London School of Hygiene and Tropical Medicine said in an article published in early April that they thought the number was 0.62.
They surveyed 1,300 people about their movements and contacts and to judge how many people they would likely have infected if they carried the virus.
And England’s medical director Professor Chris Whitty told parliamentarians at a meeting of the Science and Technology Committee last week that the R was between 0.5 and 1.
Its counterpart, Chief Scientific Adviser Sir Patrick Vallance, has also claimed that it had a similar pace, saying it is now between 0.6 and 0.9 across the UK.
At the Downing Street press conference last night, he suggested it was lower in London, adding: “It is not exactly uniform across the country.”
If the number is going down, why are we still locked up?
Substantial drops in the rate of virus reproduction and the number of people infected are vital for the UK to even consider breaking out of the blockade.
Number three on the list of five government criteria that must be met before the shutdown can end is: “The reliable data to show that the infection rate is declining to manageable levels across the board.”
While Sir Patrick and Professor Whitty say they believe the R is now below one, the government possibly lacks the “reliable data” to prove it.
COVID-19 testing, until last week, had been restricted to hospital patients and medical personnel only, meaning the true scale of the outbreak was unclear.
The tests are being implemented more widely now for people who think they might have the virus and also for more than 100,000 random people in the entire population.
A landmark report released by Imperial College London on March 30 showed politicians in the UK how the rate of reproduction of the virus could change as the country progressed through the blockade, using models from other countries that they had introduced strict social distancing measures above (pictured). That report came after one of the same team estimated that up to half a million people could die if the government failed to act, which is attributed to convincing Boris Johnson to order the nation to stay home on March 23.
Authorities will now want to see that the number of newly diagnosed cases remains low, even as testing increases, which would show that the virus is about to disappear. If the numbers continue to be low and even drop for weeks, that would show that the disease is slowly spreading.
Because so few people have had the disease and developed immunity, it is vital that the number of people currently infected decrease as much as possible before the closure is lifted, to prevent those patients from triggering another outbreak.
Dr Yates of Bath said: ‘If the UK relaxes social distancing now, while the majority of the population is still susceptible, it is at very real risk of a second wave.
‘At the moment, the suggestions are that R0 could be around 0.7, which means we have a bit of room to maneuver in the total block.
‘As long as we keep R0 below 1, the disease will continue to disappear. The reason we are waiting to complete the lock for so long is because we want to reduce the cases to a very low level and the fastest way to do this is to keep R as low as possible.
‘To some extent, the impact of several different measures is measurable and modelers are running a variety of different scenarios to advise the government on the best policy.
“But until we really go through the experiment of lifting the different restrictions, we won’t really know the effect on R. You can expect a lot of caution in the measures that the government is beginning to relax.” Expect it to be conservative initially.
Movements in the government suggest that the blockade in its current state is likely to continue until June, after Scottish Prime Minister Nicola Sturgeon said yesterday that he thought it would still be too soon for a change in next week’s quarterly review. , which will take place on May 7.
However, Professor Whitty offered a glimmer of hope at a science and technology committee meeting last week when he said that the R below one ‘gives’ a little leeway to maneuver and tick some things while keeping it below of 1 ‘ .
How will 100,000 people track the R value after the crash?
Sir Patrick Vallance, Britain’s top scientific adviser, confirmed yesterday that officials will move forward using random population tests and a number of official cases to determine how the R value changes in the future.
He said at the Downing Street briefing: “ Right now we are using a calculated R to see all kinds of things, including contacts, genomics, ambulance data, hospital admissions, etc., to calculate the R . ‘
As part of their three-point ‘test, track, track’ plan, at least 25,000 people sign up for a plan to test a sample of the population every month for a year to see if they are currently sick with the virus, tracking with time
The Robert Koch Institute in Germany is publishing the best daily estimates from the country’s R0 government, showing that it fell almost during the close of April
In a second branch of the follow-up project, people in 1,000 homes across the country will undergo monthly blood tests to see if they have immunity to the coronavirus from having been infected with it in the past.
The government will also screen 100,000 people at random in a single swab test scheme, to get an idea of what proportion of the population is currently infected.
Public Health England is conducting ongoing antibody tests in its Porton Down laboratory to build an idea of how many people have had the virus in the past and how they have developed immunity to the virus, and up to 10,000 people will be sent home for testing. antibody test. kits to add to this data.
The first results of these nationwide surveys are expected earlier this month and will help compile a picture of how many people are becoming infected with the virus and how fast it is spreading.
The London School of Hygiene & Tropical Medicine is also trying to estimate how much the virus is spreading by surveying people about their movements and social contacts in the past days and weeks.
R was estimated in April to have fallen from 2.6 to 0.62 in the first month of the UK close.
Will health managers publish the R number every day?
Health chiefs have yet to reveal whether they will publish the R number every day, despite the Prime Minister putting the number at the center of the battle in his speech yesterday.
But ministers in Germany, who have been widely praised for their rigorous approach to stopping the outbreak, offer a daily update.
Status reports released by the Robert Koch Institute, the country’s disease control center, show that R0 fell below one on April 15.
El número fluctúa a diario: fue de 0,9 el martes y de 0,75 ayer, lo que significa que puede no ser una medida confiable día a día, pero podría ser útil realizar un seguimiento a lo largo del tiempo.
Sería útil observar el número R a medida que el país sale del bloqueo porque podría revelar exactamente cómo diferentes medidas afectan la tasa de infección.
El bloqueo se produjo de una vez, pero se levantará pieza por pieza, lo que significa que el cálculo de cómo cada restricción afecta al número no se puede conocer realmente hasta que se elimine.
El Dr. Robin Thompson, investigador de epidemiología matemática de la Universidad de Oxford, dijo: “ Un desafío clave ahora es identificar medidas que se puedan relajar y que solo tengan un impacto limitado en el valor de R.
‘Una de las razones por las que esto es particularmente desafiante es que las intervenciones se introdujeron por primera vez en el Reino Unido con unos pocos días de diferencia. Como resultado, es difícil desenredar los efectos relativos de diferentes intervenciones sobre el número de reproducción ‘.
