UK R number dropped when lock was introduced

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A mass testing program that will sample 100,000 coronaviruses will have a “huge impact” on when and how the UK breaks out of the lockout.

In a national effort to determine the speed of spread of the virus in Britain, scientists have embarked on an attempt to test tens of thousands of people and begin long-term surveillance of COVID-19 cases and epidemics local.

This will help them calculate the number of times the virus reproduces – known as the R-value – which will then influence when the locking measures can begin to lift.

Prime Minister Boris Johnson confirmed yesterday that the R is now below 1, which means that the virus is spreading more slowly than in one and that the epidemic is about to end naturally.

At the start of the epidemic in the UK, the rate of R was between 2.4 and 4, according to scientists, but the dramatic home-support measures implemented on 23 March reduced it by at least two-thirds.

The virus cannot survive if the R remains below one, and the government must now step up its testing and surveillance to make sure it will never be allowed to exceed this number again.

Hundreds of thousands of tests on people across the country, whether or not they have COVID-19, will now be essential to moving forward.

Lord Ara Darzi, director of the Institute of Global Health Innovation at Imperial College London, said that a program to test 100,000 people in 315 different regions of the country is now “operational” and that the first results are expected from ‘here “a few 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 track the virus over time.

The Imperial College COVID-19 response team, which advised the government, estimated in March that the global average coronavirus R0 was 3.87. When social distancing and locking took effect, that number has now dropped below 1, potentially as low as 0.5, which means the virus will naturally disappear if this continues.

The COVID-19 response team at Imperial College, which advised the government, estimated in March that the global average coronavirus R0 was 3.87. When social distancing and locking took effect, that number has now dropped below 1, potentially as low as 0.5, which means the virus will naturally disappear if this continues.

Lord Darzi said on BBC Radio 4 this morning that the mass test project would provide a “snapshot” of the current situation in the UK which could then be followed.

He said: “We will test 100,000 people in 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 essential.

“We are operational, we have sent nearly 2,000 and it will take about two weeks to get them out and back.”

“And, of course, we need to analyze them and inform policy makers, as this will have a significant impact in terms of easing the lockdown.

“There is another study underway in Oxford in 20,000 households that will be repeated tests … so the combination of these two studies will be very informative in terms of moving to the next phase.” “

HOW THE TEST WILL FOLLOW THE R VALUE OF THE VIRUS AND THE MONITOR-19 COVIDE

As it steps up monitoring for COVID-19, the government is now moving on to four major population testing programs:

100,000 RANDOM TESTS

Imperial College London will oversee the two-part REACT program (real-time assessment of community transmission).

The first part of this will be 100,000 tests of random people in 315 different regions of the UK, to see how many of them are currently infected.

RANDOM ANTIBODY HOME TESTS

The second part will be a rollout of home antibody tests, which can tell if people have had the disease before and have recovered. These will be given to 300 people for a first try and then extended to 10,000 people and then to 100,000 if successful.

Antibody tests will create a picture of the number of people who have already had the virus and can be immunized against it, which means they will not get it any more, at least in the short term.

REGULAR TESTS OVER 25,000

These two test phases will coincide with two other long-term programs announced last week as part of the government’s “test, track, trace” plan.

At least 25,000 people will be enrolled in a program where they will undergo regular swabs at monthly intervals to see if they are infected at that time. This will continue over the next year and will be extended to 300,000 people if it proves useful.

REGULAR ANTIBODY TEST

And more antibody tests will be rolled out in 1,000 households across the country where people will donate blood samples for testing to test if they have developed immunity to the virus.

Sir Patrick Vallance, Britain’s chief scientific adviser, confirmed yesterday that officials are using population tests and data on official coronavirus cases to determine the rate of spread of the virus, signified by its R or R0 value .

He said, “Right now, we’re using a calculated R that looks at all kinds of things, including contacts, genomics, ambulance data, hospital admissions, etc., to calculate the R.”

Lord Ara Darzi, director of the Institute of Global Health Innovation at Imperial College London, explained this morning on BBC Radio 4: ‘[This] will be a snapshot of the R value across the country. We will test 100,000 people in 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 essential.

“We are operational, we have sent nearly 2000 and it will take about two weeks to get them out and back, and we obviously need to analyze them and inform policy makers, as this will have a significant impact in terms of easing the lockdown .

“There is another study underway in Oxford in 20,000 households that will be repeated tests … so the combination of these two studies will be very informative in terms of moving to the next phase.” “

CONTACT TRACING

In addition to stepping up testing, the government will also employ an army of 18,000 contact tracers – likely to be reassigned to government officials – by mid-May.

These will be responsible for contacting people who have tested positive for the coronavirus and collecting details on the social networks around them, allowing them to isolate people who may have it and prevent them from further spreading it. .

Prime Minister Boris Johnson put the R-value at the heart of the British coronavirus battle yesterday at his press conference in Downing Street, when he revealed the government’s commitment to keep it below 1.

It is currently estimated to be between 0.6 and 0.9, which means that every 10 people infected with the virus should pass it on to six to nine others.

This means that as long as the number of reproductions can be kept below 1, the epidemic will eventually run out of course and end naturally.

The lifting of the foreclosure measures will, however, increase and politicians are now under pressure to juggle the damage caused by an economic closure with the damage that would be caused by a second epidemic and a second lock-out.

Because so few people have had the disease and developed immunity, it is essential that the number of people currently infected is kept as low as possible before the isolation is lifted, in order to prevent these patients from triggering another epidemic. .

Dr. Kit Yates, Lecturer in Mathematical Biology at the University of Bath and author of The Maths of Life and Death, told MailOnline: “The reason we hold onto locking for so long is because we want to bring the cases down to a very low level and the quickest way to do this is to keep R as low as possible. “

He added: “Until we go through the experience of lifting the different restrictions, we won’t really know the effect on R.

“You can expect a lot of caution in the measures the government is starting to relax. Expect him to be conservative at the start.

As it steps up monitoring for COVID-19, the government is now moving on to four major population testing programs.

Imperial College London will oversee the two-part REACT program (real-time assessment of community transmission).

The first part of this will be 100,000 tests of random people in 315 different parts of the UK to see how many of them are currently infected – this is the scheme Lord Darzi referred to.

The second part will be a rollout of home antibody tests, which can tell if people have had the disease before and have recovered. These will be given to 300 people for a first try and then extended to 10,000 people and then to 100,000 if successful.

Antibody tests will create a picture of the number of people who have already had the virus and can be immunized against it, which means they will not get it any more, at least in the short term.

These two test phases will coincide with two other long-term programs announced last week as part of the government’s “test, track, trace” plan.

At least 25,000 people will be enrolled in a program where they will undergo regular swabs at monthly intervals to see if they are infected at that time.

This will continue over the next year and will be extended to 300,000 people if it proves useful.

And more antibody tests will be rolled out in 1,000 households across the country where people will donate blood samples for testing to test if they have developed immunity to the virus.

Dr Yates of the University of Bath added: “Looking at the evolution of the number of cases can give us an idea of ​​the current value of R.

“If we see that the cases are decreasing, it strongly suggests that R is less than one.

“Modelers can adapt their models to case data (or perhaps more reliably death) in order to reverse engineer the value of R that best fits. Hospital admission data can also give us an idea and may be a little more reliable than the test numbers.

How the UK R number dropped when the lock was introduced and what it means for the emergence on the other side

Prime Minister Boris Johnson last night put detailed science at the heart of Britain’s coronavirus crisis and said that the status of the lockout now depends on the virus’s breeding number – known as R.

Monitoring the number of new patients and the rate at which it is increasing or decreasing will be the best way for authorities to monitor the rate of spread of the virus, which in turn will guide the risks the government believes it can take by lifting the lock.

The data that presents Britain’s R-value will shape everyone’s life in the UK in the weeks and months to come, and MailOnline explains here how:

What is the R number?

Each infectious disease is assigned a reproduction number, known as R0 – pronounced “R naught” – or simply R.

This is a value that represents the average number of people that a sick person will infect.

Most epidemiologists – scientists who track disease outbreaks – believe that the SARS-CoV-2 virus, which causes COVID-19, has an R value of about 3.

But some experts analyzing epidemics 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 the speed of spread of the virus depends on the environment.

As an epidemic progresses, R can simply be called R, which means the effective rate of infection – nothing assumes that no one in the population is protected, which becomes obsolete as as more and more people recover.

How does reproduction rate compare to other infections?

SARS-CoV-2 is thought 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 between 12 and 18 if it is 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 collective immunity. So many people get it when they are children and become immune to reinfection that it cannot spread among adults.

Seasonal flu has an R value of about 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 anyone else.

The Ebola virus has an R0 of between 1.4 and 1.8 – which is low, but has so far only spread to countries with poor health facilities and its extremely high mortality rate ( 50%) makes it a threat.

Mumps has an R0 between 10 and 12, which makes it very contagious, but the measles vaccine (MMR) protects most people in Britain from getting it.

The R0 for pertussis, medically known as pertussis, is estimated to be 5.5. The NHS urges mothers to be vaccinated against pertussis during pregnancy, as they are able to transmit immunity to their babies naturally.

How is it calculated? And can scientists ever be sure of the number?

The R is not a fixed number and scientists calculate it by studying the speed of spread of the virus in its perfect environment and also in society.

Although the biology of the virus and its spread – whether through cough or blood, for example – will have some influence, but human behavior is a more important factor.

Tracking the increase in the number of new cases and the rate at which the number of patients doubles are two of the best ways to estimate R, according to a lecturer in 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 as that or as low as that.

“R0 is not a fundamental property of the virus. This will change depending on the community through which the disease passes.

” [It] depends on three factors: communicability (the ease with which the disease passes between people); the infectious period (the longer it is, the more likely it is for an infectious person to transmit the disease); and the population affected by the disease.

“The more people and the more packed they are, the easier it will be for the disease to spread, so we can’t just take the R0 measured in one country and use it in another. “

Dr. Jennifer Cole, biological anthropologist at Royal Holloway University in London, said: “It is incredibly difficult to calculate [the R0] without doing it in retrospect.

She said detailed data can show how quickly the virus has spread, but is more accurate when you look back in time, not right now.

“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 the R0 is between one and two, or between three and four, this is broad enough to make the decisions you need on social distancing.

Did the UK R number drop when the lock was introduced?

The COVID-19 intervention team at Imperial College London estimated that the R0 value for coronavirus in the UK was 2.4 before the lockout started.

This meant that, before Prime Minister Boris Johnson ordered the national closure on March 23, 10 people infected with the virus would infect 24 others.

But scientists have since calculated that the rate has dropped below 1, which means that the crisis will end if the situation remains the same.

Researchers at the London School of Hygiene & Tropical Medicine said in an article published in early April that they thought the number was 0.62.

They interviewed 1,300 people about their whereabouts and contacts and to judge how many people they were likely to have infected if they carried the virus.

And England’s chief medical officer, Professor Chris Whitty, told MEPs at a science and technology committee meeting last week that the R was between 0.5 and 1.

His counterpart – chief scientific adviser Sir Patrick Vallance – also said the rate was similar, saying it is now between 0.6 and 0.9 in the UK.

Last night at the Downing Street press conference he suggested it was lower in London and added, “It is not exactly uniform across the country.”

If the number goes down, why are we still locked out?

Substantial reductions in the virus’s reproduction rate and the number of people infected are vital for the UK to even consider breaking the deadlock.

Number three on the government’s list of five criteria that must be met before the lockout ends is: “Reliable data to show that the infection rate is decreasing to manageable levels at all levels.”

While Sir Patrick and Professor Whitty say they believe the R is now less than one, the government probably lacks “reliable data” to prove it.

Until last week, COVID-19 testing had been limited to inpatients and medical personnel only, which meant that the true extent of the epidemic was unclear.

Now, the tests are deployed more widely with people who think they have the virus and also with more than 100,000 random people in the population.

A landmark report released by Imperial College London on March 30 showed politicians in the UK how the reproductive rate of the virus could change as the country progressed in lockdown, using models of other countries that had introduced strict social distancing measures earlier (illustrated in the series). This report came after that of the same team which estimated that up to half a million people could die if the government did not act, which is credited with having persuaded Boris Johnson to order the nation to stay home on March 23

A landmark report released by Imperial College London on March 30 showed politicians in the UK how the reproductive rate of the virus could change as the country progressed in lockdown, using models of other countries that had introduced strict social distancing measures earlier (illustrated in the series). This report came after that of the same team which estimated that up to half a million people could die if the government did not act, which is credited with having persuaded Boris Johnson to order the nation to stay home on March 23

Officials will now want to see the number of new cases diagnosed remain low even if they step up testing, which would show that the virus is on the way out. If the numbers continue to stay low and even go down for weeks, it would show that the disease is spreading slowly.

Because so few people have had the disease and developed immunity, it is essential that the number of people currently infected is kept as low as possible before the isolation is lifted, in order to prevent these patients from triggering another epidemic. .

Dr Yates of Bath said: “If the UK is easing social distance now, while most of the population is still sensitive, it runs the very real risk of a second wave.

“Right now, it is suggested that R0 could be around 0.7, which means that we have a bit of leeway to abandon full lockout.

ROSE DENMARK INFECTION RATES AFTER SCHOOL REOPENING

Danish authorities sent the children back to school two weeks ago and since then the rate of spread of coronaviruses has increased, according to officials.

The country experienced a relatively small outbreak, with only 9,356 officially diagnosed cases and 452 deaths.

As a result, it has undergone a shorter lockout and has already started to relax the restrictions.

However, the national infectious disease agency, Status for Smittetrykket I Danmark (SSI), has found that the virus’s reproduction rate has dropped to almost 1 – which could spark another epidemic – since schools reopened on 20 April.

It went from 0.6 to 0.9 during this period, reported The Local.

Research released earlier this week will prompt governments to think twice before reopening schools after revealing that children appear to be just as likely to catch and spread COVID-19 as adults.

In its status report, the SSI said: “There is no evidence that there is a real acceleration of the epidemic.”

“As long as we keep R0 below 1, the disease will continue to go away. The reason we keep the lock on for so long is because we want to bring the cases down to a very low level and the quickest way to do this is to keep R as low as possible.

“To a certain extent, the impact of various different measures is quantifiable and the modellers are faced with a series of different scenarios in order to advise the government on the best policy.

“But until we have the experience 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 starting to relax. Expect him to be conservative at the start.

Movements in government suggest that locking in of its current state should continue until June, after Scottish Prime Minister Nicola Sturgeon said yesterday that she thought it would be too soon to change when next week’s triennial review, to be held on May 7.

Professor Whitty, however, offered a glimmer of hope at a science and technology committee meeting last week when he said that the R being less than “gives a little leeway and check some things while keeping it below 1 “. .

How will the 100,000 people test follow the R value after the lockout?

Sir Patrick Vallance, Britain’s chief scientific adviser, confirmed yesterday that officials will go ahead using random population tests and the number of official cases to determine how the R-value will change in the future.

He said during the Downing Street briefing: “At the moment we are using an R calculated by looking at all kinds of things, including contacts, genomics, ambulance data, hospital admissions, etc. to calculate the R. “

As part of its three-point test, follow-up and follow-up plan, at least 25,000 people are enrolled in a plan to test a sample of the population each month for a year to see if they are currently infected with the virus, monitoring over time.

The German Robert Koch Institute publishes the government's best daily estimates of the country's R0, showing that it almost fell during the April lockout

The German Robert Koch Institute publishes the government’s best daily estimates of the country’s R0, showing that it almost fell during the April lockout

WHAT IS R0?

Each infectious disease is given a reproduction number, known as R0 – pronounced “R naught”.

This is a value that represents the average number of people that a sick person will infect.

WHAT IS R0 FOR COVID-19?

The R0 value for SARS-CoV-2, the virus that causes COVID-19, was estimated by the Imperial College COVID-19 response team to be 2.4 in the UK before the lockout started.

But some experts analyzing epidemics around the world have estimated that it could be closer to the 6.6 mark.

Estimates of R0 vary as the true size of the pandemic remains a mystery and the speed of spread of the virus depends on the environment.

It will spread more quickly in a densely populated city where people travel by metro than in a rural community where people drive everywhere.

HOW DOES IT COMPARE WITH OTHER VIRUSES?

It is thought to be at least 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 12 to 18 if it is not controlled. Widespread vaccination keeps it suppressed in most developed countries.

It is estimated that the R0 of chickenpox is between 10 and 12, while the seasonal flu has a value of around 1.5.

WHY IS IT IMPORTANT TO HAVE A LOW R0?

The higher the R0 value, the more difficult it is for health officials to control the spread of the disease.

A number less than one means that the epidemic will run out of steam and be forced to end.

In fact, the infectious disease will quickly miss new victims to strike.

HOW DOES A LOCK REDUCE R0?

The UK’s draconian lockdown, imposed on March 23, has slowed the coronavirus crisis in Britain, according to studies.

Last month, scientists from the London School of Hygiene and Tropical Medicine analyzed the virus in the UK.

They estimated that each infected patient could now transmit only COVID-19 to 0.62 others, against 2.6.

The team said the virus had trouble spreading because people had less contact with others.

They used a survey of 1,300 people who were asked to list the human contacts they have had in the past 24 hours.

This was compared to a similar survey carried out in 2005 to give an idea of ​​how it had changed due to the foreclosure.

Dans une deuxième branche du projet de suivi, des personnes dans 1 000 ménages à travers le pays se soumettront à des analyses sanguines mensuelles pour voir si elles sont immunisées contre le coronavirus d’être infectées par celui-ci dans le passé.

Le gouvernement testera également 100 000 personnes au hasard dans le cadre d’un programme unique de tests sur écouvillon, pour avoir une idée de la proportion de la population actuellement infectée.

Public Health England effectue actuellement des tests d’anticorps dans son laboratoire de Porton Down pour se faire une idée du nombre de personnes qui ont eu le virus dans le passé et de la façon dont elles y ont développé une immunité, et jusqu’à 10 000 personnes seront renvoyées chez elles kits à ajouter à ces données.

Les premiers résultats de ces enquêtes nationales sont attendus au début du mois et aideront à rassembler une image du nombre de personnes infectées par le virus et de sa vitesse de propagation.

La London School of Hygiene & Tropical Medicine tente également d’estimer l’ampleur de la propagation du virus en interrogeant les gens sur leurs mouvements et leurs contacts sociaux au cours des derniers jours et semaines.

Il a estimé en avril que le R était passé de 2,6 à 0,62 au cours du premier mois du verrouillage britannique.

Les chefs de santé publieront-ils le numéro R tous les jours?

Les chefs de la santé n’ont pas encore révélé s’ils publieraient le numéro R chaque jour, malgré le fait que le Premier ministre ait mis le numéro au cœur de la bataille dans son discours d’hier.

Mais les ministres allemands – qui ont été largement félicités pour leur approche rigoureuse pour arrêter la flambée – fournissent une mise à jour quotidienne.

Les rapports de situation publiés par l’Institut Robert Koch, le centre du pays pour le contrôle des maladies, montrent que le R0 est tombé en dessous de un le 15 avril.

Le nombre fluctue quotidiennement – il était de 0,9 mardi et de 0,75 hier, ce qui signifie que ce n’est peut-être pas une mesure fiable au jour le jour, mais pourrait être utile pour suivre au fil du temps.

Il serait utile de surveiller le nombre R à la sortie du pays du verrouillage, car cela pourrait révéler exactement comment différentes mesures affectent le taux d’infection.

Le verrouillage s’est produit en une seule fois, mais sera levé pièce par pièce, ce qui signifie que le calcul de la façon dont chaque restriction affecte le nombre ne peut pas vraiment être connu jusqu’à ce qu’il soit supprimé.

Le Dr Robin Thompson, chercheur en épidémiologie mathématique à l’Université d’Oxford, a déclaré: «  Un défi clé consiste maintenant à identifier des mesures pouvant être assouplies qui n’ont que des impacts limités sur la valeur de R.

«L’une des raisons pour lesquelles cela est particulièrement difficile est que les interventions ont d’abord été introduites au Royaume-Uni à quelques jours d’intervalle. Par conséquent, il est difficile de démêler les effets relatifs de différentes interventions sur le nombre de reproducteurs. “

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