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Coronavirus UK: herd immunity could develop from 10% infected


According to a study, herd immunity to Covid-19 could develop if only 10 percent of the population developed the disease.

Scientists say that if a vaccine were developed, it would have to be 60 to 70 percent covered – but this threshold could be significantly lower for natural immunity.

The concept of herd immunity depends on the fact that people are affected only once, so that a certain number of people who have already been infected with the virus can no longer spread.

It remains a mystery whether this is the case with Covid-19, but if it is, herd immunity could offer some protection during a second wave of the disease that the best medical professionals fear this winter.

Researchers are now saying that it could work to some extent if only one or two in ten people were naturally infected and become immune to the disease.

They said higher estimates assumed that everyone would be immune to a vaccine, but in fact, the people who get infected first are probably still the most at risk. So if they develop an immunity, they are less at risk.

For example, health workers, people living in cities, and people facing jobs, such as drivers, store workers, school children, and teachers.

According to scientists, the immunity of the most socially active people could protect those who come into contact with fewer others.

Another study has followed a similar line and suspected that herd immunity could develop in around 43 percent of the infected population.

Britain as a whole is not close to herd immunity. According to government surveys, between five and six percent of the population has had Covid-19 – about three million people.

However, London has had a much higher infection rate in the past at an estimated 17.5 percent and could therefore approach a low level of protection.

Scientists say that if a vaccine were developed, it would have to be 60 to 70 percent covered – but this threshold could be significantly lower for natural immunity

In the of Dr. Gabriela Gomes, a mathematician at the Liverpool School of Tropical Medicine and the University of Strathclyde, said: "In idealized scenarios of randomly delivered vaccines and randomly mixed people, the threshold values ​​for herd immunity are given by a simple formula that suggests in the In the case of SARS-CoV-2, 60 to 70 percent of the population would need to be immunized to stop the spread if estimates of R0 between 2.5 and 3 are taken into account.

& # 39; A critical limitation in exporting these natural infection immunization calculations is that natural infections do not occur accidentally.

“People who are more vulnerable or more exposed are more susceptible to infection and become immune, which lowers the threshold.

"In our model, the herd immunity threshold drops sharply … and remains below 20 percent for more variable populations."

The concept of the reduced herd immunity threshold by Dr. Gomes is based on the affected population groups.

For example, the corona virus appears to spread most in cities and among healthcare workers and people who work in jobs that mix with a lot of people, such as factory workers or taxi drivers.

You then run the risk of passing it on to people who are inherently less at risk – someone who lives in a city but travels to friends or relatives in the country, for example, or a caregiver who lives in more than one house in a week is working.

Immunity could also develop in places where there are strong local outbreaks.

In turn, if workers are immune to outbreaks in food factories around the world, this could benefit families and communities around the plants – even if they didn't have the disease personally.

Natural immunity has a lower threshold than vaccines that are randomly or evenly distributed across the population, the scientists said in the article, which was not published in a journal.

Scientists suggest that herd immunity may develop if immunity develops in the places where the coronavirus is most likely to spread - among people with more social interaction and in busy cities - because fewer people find the virus elsewhere (Image: Drinkers in Soho, London, on Saturday 4th July when the pubs reopened for the first time)

Scientists suggest that herd immunity may develop if immunity develops in the places where the coronavirus is most likely to spread – among people with more social interaction and in busy cities – because fewer people find the virus elsewhere (Image: Drinkers in Soho, London, on Saturday 4th July when the pubs reopened for the first time)

Since many vaccines are given to people who are already at low risk of contracting the virus, more would be needed to ensure that people at high risk get it.

This increases the percentage coverage that healthcare would need to achieve to achieve herd immunity.

WHAT IS HERD IMMUNITY?

Herd immunity is a situation in which a population of people is protected from an illness because so many of them are unaffected – because they have had it or have been vaccinated – that it cannot spread.

In order to cause an outbreak, disease-causing bacteria or viruses must constantly have potential victims who are not immune to it.

Immunity is when your body knows exactly how to fight off a certain type of infection because it has come across it, either from past illness or from a vaccine.

When a virus or bacterium enters the body, the immune system creates substances called antibodies that are designed to destroy a certain type of insect.

Once created, some of them remain in the body and the body also remembers how to restore them. This provides long-term protection or immunity to a disease.

If nobody is immune to a disease – as was the case at the beginning of the coronavirus outbreak – it can spread like wildfire.

However, if, for example, half of the people have developed immunity – due to a previous infection or a vaccine – there are only half as many people to whom the disease can spread.

As more and more people become immune, the beetle finds it increasingly difficult to spread until its victim pool becomes so small that it can no longer spread.

The herd immunity threshold varies for different diseases depending on how contagious they are. With measles, around 95 percent of people must be vaccinated against the spread.

For polio, which is less contagious, the threshold, according to the Oxford Vaccine Group, is around 80 to 85 percent.

The study was carried out by experts from the Universities of Stockholm and Nottingham, who estimated that herd immunity could develop from natural infections in around 43 percent.

These researchers said that the key to understanding coronavirus herd immunity is social activity.

The virus is significantly more likely to infect people who come into contact with more people, while many others come into contact with fewer people than average.

The study divided people into three groups: people with an average number of interactions, people with "high activity" – 50 percent more than average and people with "low activity" – 50 percent less than average.

If the virus spreads more widely in the most socially active group, the level of immunity they build could protect people in the less active groups.

This is because the more active people come into contact with others more regularly and are therefore more likely to spread the disease.

People with fewer interactions are less likely to get the disease – because it most commonly spreads through close contact – and less likely to pass it on because they go through the disease more often and recover without seeing anyone.

Professor Frank Ball, Professor Tom Britton and Professor Pieter Trapman – three authors of the study – wrote in the journal Science: "Our application to Covid-19 shows a reduction in herd immunity from 60 percent … immunization to 43 percent in a structured population, but this should be interpreted as an illustration rather than an exact value or even a best estimate. & # 39;

They said that immunity would be stronger in cities, large households and large jobs.

However, this could also reflect where the virus would be most likely to spread in future outbreaks, meaning that those in rural areas or smaller offices would have some level of protection just to have fewer people.

Government blood tests have shown that around 5.4 percent of people in England already had the virus. According to the National Statistics Office, the ballpark is between 4.3 and 6.5 percent.

This means that around three million people already had the virus – far from enough for herd immunity.

However, theories assume that London is much closer to herd immunity than other regions.

Public Health England tests have shown that around 17.5 percent of people living in the capital have antibodies to the disease, which means that their immune system has already warded them off.

According to PHE data, this is very different across the country. Around 12 percent of people are exposed in the north west and 10 percent in the east of England, but less than 10 percent in any other region.

The lowest are the southeast and the northeast, where only about four percent of people appear to have been ill.

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