Example from Spain shows that the world will need new quarantines

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One of the main current scientific challenges in fighting the pandemic is to discover the real size of the pandemic.

Today, with the difficulty of doing mass tests, we only have an idea of ​​how many people have been infected. Knowing the true dimension of the problem is fundamental to understanding where we are and what to expect in the near future.

One of the most robust efforts to find these answers is being made in Spain, where a national study has just released its first results – and they point out, according to experts heard by BBC News Brasil, that next waves of contagion and new quarantine periods may be inevitable.

The survey carried out by the Instituto de Saúde Carlos 3º, linked to the Spanish government, applied rapid serological tests to 60,983 people across the country.

The aim was to look for antibodies to the disease in the blood samples and estimate from that the proportion of the population that was infected.

The scientists concluded that only 5% of Spain’s inhabitants, or 2.35 million people, were infected by the pandemic.

Although it is quite people in absolute terms, it is a small proportion in relation to the size of the chaos experienced by the country, which saw its health system collapse and was forced to enter the middle of March in one of the most rigid lockdowns in the world to contain the spread of the virus.

The index is also far from what is necessary for the so-called “group immunity”, or “herd effect”, which would be able to naturally prevent new waves of contagion.

Man walks past painting in which people kiss in mask
Image captionSpanish study is one of the main efforts to know the real size of the pandemic

This occurs when 60% to 70% of a population already has antibodies against a virus or bacteria.

If this happens, even those who do not have immunity against this threat benefit indirectly, because they are protected by being surrounded by people who are immune.

It is more difficult to be infected in such a situation, and this immune barrier prevents a microorganism from spreading and causing an outbreak.

‘A lot of susceptible people’

But the example of Spain, where the first case was identified on January 31 and, after just over three months, only 5% of the population was infected, points out that group immunity can hardly be obtained naturally in the short or medium term.

“There are still a lot of people susceptible to catching the virus. From the moment that life returns to normal, the chance of having new epidemics is great ”, says the sanitary doctor Ana Freitas Ribeiro, from the epidemiology service of the Emílio Ribas Institute, in São Paulo.

The proportion of people with antibodies in the population identified by the Spanish study was not uniform across the country.

The autonomous community of Ceuta, on the coast of North Africa, had the lowest rate, at 1.1%. The largest was identified in the autonomous community of Madrid, where 11.3% of participants had antibodies.

But even the rate registered in the Spanish capital region would not be enough, says Fernando Spilki, president of the Brazilian Society of Virology.

“Even in the hardest-hit regions, there are still very few people with antibodies. Natural immunization is not taking place as it should in order to overcome the pandemic ”, says Spilki.

Epidemiologist Antonio Augusto Moura da Silva, a professor in the Department of Public Health at the Federal University of Maranhão (UFMA), says that, given these rates, “everyone will expect a second wave” of contagions.

“We are still in the first one and we do not know when the second will come, but in some countries that are coming out of isolation, the epidemic is already beginning to manifest itself again,” says Silva.

Another way to achieve the herd effect would be with a vaccine. However, most experts say that one should only be ready in the middle of next year, that is, 12 to 18 months after Sars-Cov-2 is identified,

“Until that happens, we will have to do periods of social isolation whenever our health systems detect an increase in the number of cases,” says Ribeiro.

Immunologist Renato Astray, a researcher at the Butantan Institute, also assesses that, like Spain, Brazil will be subject to new epidemics – and quarantines.

“As soon as we stop the isolation, because the cases will be decreasing, we will have an infected rate that is not very different from the rate in Spain and, more or less days, we will have another outbreak. And we, like them, are going to have to take isolation measures more often, it won’t stop there, ”says Astray.

Lethality

The Spanish survey also revealed some important information about the pandemic.

By estimating the number of people infected in Spain, the study allows to identify a lethality rate of the virus that is closer to the real index.

Ribeiro points out that this rate was estimated at 11.9% in Spain, where there have been 27,459 deaths so far among 230,183 confirmed cases, according to data from Johns Hopkins University.

But the doctor says that lethality is 1.1% when the number of deaths is compared to the estimate that there have been 2.35 million infections in the country so far.

People carry coffins wearing protective clothing in Russia
Image captionWithout control measures, such as social isolation, millions of people could die

It is a much lower index than the previous one, but Ribeiro points out that it is still ten times higher than the 0.1% seasonal flu virus.

Along with the fact that the coronavirus is highly transmissible – it is estimated that each infected person contaminates another three – this can lead to catastrophe.

“Taking into account large populations, like the almost 50 million inhabitants in Spain or the 210 million in Brazil, without any measures to contain the virus, the number of infections increases a lot, and having 1% of deaths would mean the death of many people ”, Says Ribeiro.

The experts heard by the report say that this destroys any claim to use the “herd effect” as a strategy to fight the pandemic, as was considered by the UK government, for example.

The social cost of a mass infection would be huge, Astray says. “When people talk about everyone getting infected right away and getting rid of it at once, you need to see what Spain has already suffered from 5%. Imagine if it reached 10% or 20%? It would be a war situation ”, says the immunologist.

Antonio Augusto Moura da Silva calculates that, with a lethality rate at the same level as Spain, achieving group immunity would cost from 1.4 million to 1.6 million lives. “It would be the equivalent of dying an entire Curitiba or Recife,” says the epidemiologist.

Asymptomatic

Silva highlights another very important fact pointed out by the study: about a third of the participants who had antibodies against the new coronavirus said they had no symptoms.

“We were looking for that number of asymptomatic people,” says the epidemiologist.

Together with people who tested positive and showed only two symptoms, the group now represents 50% of the total infected.

This gives a better idea of ​​the size of the challenge, which is to identify and isolate who was infected to break the chain of transmission of the virus and control the pandemic.

Man walks in mask and with stroller in front of mural in France
Image captionResearch indicates that one third of those infected have no symptoms

“Half of the people who are infected with the pandemic do not know this because they have no symptom or have a very mild symptom, such as a headache and runny nose, for example, and this is not necessarily associated with this disease. These people continue to circulate and transmit the virus ”, says Silva.

The epidemiologist Lúcio Botelho, professor at the Department of Public Health at the Federal University of Santa Catarina (UFSC), considers this index “scary”.

Especially since only 2.55% of the research participants said they had been tested for covid-19 with molecular tests, which are the ones that allow the diagnosis of the disease.

“Without being able to do mass tests, we have no way of knowing who is transmitting the virus or not. This means that isolation is fundamental, because it is the only way we have today to prevent this from happening, ”says Botelho.

Open questions

Finally, the Spanish study points out that, among people who had done a molecular test, 87% had antibodies against Sars-cov-2.

This is a good sign, because it points out that our body develops some form of protection against this new virus.

In the research, only the antibodies known with Igg were analyzed, which are those created so that the organism is able in the future to combat the same threat more efficiently.

Immunologist Renato Astray estimates that the rate of 13% who did not develop antibodies may have been caused by a diagnostic error, because the rapid tests used in this phase of the study give results with an accuracy rate of only 79%.

Indigenous child wearing a mask puts headdress on coffin in Brazil
Image captionLower index of children with antibodies intrigues experts

Astray says that it will only be possible to confirm or refute this hypothesis in the next stages of the research, when a type of laboratory antibody test will be carried out that has a greater accuracy, around 95%

More research will also be needed to understand whether this immune response is really effective.

“Having antibodies does not necessarily mean being protected, because this antibody needs to be of the neutralizing type to prevent the virus from infecting the cell,” says the immunologist.

Virologist Aguinaldo Pinto, professor at the Department of Microbiology, Immunology and Parasitology at UFSC, explains that this does not happen, for example, with the HIV virus.

“A person who has HIV has an enormous amount of Igg antibodies, but they are never neutralizing, and the patient develops AIDS if he does not receive treatment,” says Pinto.

Another important aspect is to check if this immunity is short or long term. The virologist says that even when we develop an antibody, it does not necessarily remain forever in the body.

“This happens with mumps, for example, which generates long-term immune memory, but not with rotavirus, which causes diarrhea in a child. The antibody against it lasts for a while and then disappears. We will only find out in which case the coronavirus fits over time ”, says Pinto.

More research will also be needed to understand an intriguing aspect of the data presented so far by the Spanish study.

The rate of participants with antibodies is quite different between age groups. The rates in children aged 0 to 9 years vary between 1.1% and 3% and are significantly lower than among the elderly, who have rates between 5.1% and 6.9%.

“What would be expected would be that most groups had the same antibody production,” says Pinto.

One possible explanation is that the immune systems of very young children are still forming, which would lead to less antibody production.

But this should also be seen in the elderly, because our immune system starts to deteriorate from the age of 60, which impairs its functioning, says Astray.

“Are the different levels because the children had less exposure to the virus or because they did not develop antibodies? This is a question that remains. ”

Source: https://www.bbc.com/portuguese/internacional-52685597

One of the main current scientific challenges in fighting the pandemic is to discover the real size of the pandemic.

Today, with the difficulty of doing mass tests, we only have an idea of ​​how many people have been infected. Knowing the true dimension of the problem is fundamental to understanding where we are and what to expect in the near future.

One of the most robust efforts to find these answers is being made in Spain, where a national study has just released its first results – and they point out, according to experts heard by BBC News Brasil, that next waves of contagion and new quarantine periods may be inevitable.

The survey carried out by the Instituto de Saúde Carlos 3º, linked to the Spanish government, applied rapid serological tests to 60,983 people across the country.

The aim was to look for antibodies to the disease in the blood samples and estimate from that the proportion of the population that was infected.

The scientists concluded that only 5% of Spain’s inhabitants, or 2.35 million people, were infected by the pandemic.

Although it is quite people in absolute terms, it is a small proportion in relation to the size of the chaos experienced by the country, which saw its health system collapse and was forced to enter the middle of March in one of the most rigid lockdowns in the world to contain the spread of the virus.

The index is also far from what is necessary for the so-called “group immunity”, or “herd effect”, which would be able to naturally prevent new waves of contagion.

Man walks past painting in which people kiss in mask
Image captionSpanish study is one of the main efforts to know the real size of the pandemic

This occurs when 60% to 70% of a population already has antibodies against a virus or bacteria.

If this happens, even those who do not have immunity against this threat benefit indirectly, because they are protected by being surrounded by people who are immune.

It is more difficult to be infected in such a situation, and this immune barrier prevents a microorganism from spreading and causing an outbreak.

‘A lot of susceptible people’

But the example of Spain, where the first case was identified on January 31 and, after just over three months, only 5% of the population was infected, points out that group immunity can hardly be obtained naturally in the short or medium term.

“There are still a lot of people susceptible to catching the virus. From the moment that life returns to normal, the chance of having new epidemics is great ”, says the sanitary doctor Ana Freitas Ribeiro, from the epidemiology service of the Emílio Ribas Institute, in São Paulo.

The proportion of people with antibodies in the population identified by the Spanish study was not uniform across the country.

The autonomous community of Ceuta, on the coast of North Africa, had the lowest rate, at 1.1%. The largest was identified in the autonomous community of Madrid, where 11.3% of participants had antibodies.

But even the rate registered in the Spanish capital region would not be enough, says Fernando Spilki, president of the Brazilian Society of Virology.

“Even in the hardest-hit regions, there are still very few people with antibodies. Natural immunization is not taking place as it should in order to overcome the pandemic ”, says Spilki.

Epidemiologist Antonio Augusto Moura da Silva, a professor in the Department of Public Health at the Federal University of Maranhão (UFMA), says that, given these rates, “everyone will expect a second wave” of contagions.

“We are still in the first one and we do not know when the second will come, but in some countries that are coming out of isolation, the epidemic is already beginning to manifest itself again,” says Silva.

Another way to achieve the herd effect would be with a vaccine. However, most experts say that one should only be ready in the middle of next year, that is, 12 to 18 months after Sars-Cov-2 is identified,

“Until that happens, we will have to do periods of social isolation whenever our health systems detect an increase in the number of cases,” says Ribeiro.

Immunologist Renato Astray, a researcher at the Butantan Institute, also assesses that, like Spain, Brazil will be subject to new epidemics – and quarantines.

“As soon as we stop the isolation, because the cases will be decreasing, we will have an infected rate that is not very different from the rate in Spain and, more or less days, we will have another outbreak. And we, like them, are going to have to take isolation measures more often, it won’t stop there, ”says Astray.

Lethality

The Spanish survey also revealed some important information about the pandemic.

By estimating the number of people infected in Spain, the study allows to identify a lethality rate of the virus that is closer to the real index.

Ribeiro points out that this rate was estimated at 11.9% in Spain, where there have been 27,459 deaths so far among 230,183 confirmed cases, according to data from Johns Hopkins University.

But the doctor says that lethality is 1.1% when the number of deaths is compared to the estimate that there have been 2.35 million infections in the country so far.

People carry coffins wearing protective clothing in Russia
Image captionWithout control measures, such as social isolation, millions of people could die

It is a much lower index than the previous one, but Ribeiro points out that it is still ten times higher than the 0.1% seasonal flu virus.

Along with the fact that the coronavirus is highly transmissible – it is estimated that each infected person contaminates another three – this can lead to catastrophe.

“Taking into account large populations, like the almost 50 million inhabitants in Spain or the 210 million in Brazil, without any measures to contain the virus, the number of infections increases a lot, and having 1% of deaths would mean the death of many people ”, Says Ribeiro.

The experts heard by the report say that this destroys any claim to use the “herd effect” as a strategy to fight the pandemic, as was considered by the UK government, for example.

The social cost of a mass infection would be huge, Astray says. “When people talk about everyone getting infected right away and getting rid of it at once, you need to see what Spain has already suffered from 5%. Imagine if it reached 10% or 20%? It would be a war situation ”, says the immunologist.

Antonio Augusto Moura da Silva calculates that, with a lethality rate at the same level as Spain, achieving group immunity would cost from 1.4 million to 1.6 million lives. “It would be the equivalent of dying an entire Curitiba or Recife,” says the epidemiologist.

Asymptomatic

Silva highlights another very important fact pointed out by the study: about a third of the participants who had antibodies against the new coronavirus said they had no symptoms.

“We were looking for that number of asymptomatic people,” says the epidemiologist.

Together with people who tested positive and showed only two symptoms, the group now represents 50% of the total infected.

This gives a better idea of ​​the size of the challenge, which is to identify and isolate who was infected to break the chain of transmission of the virus and control the pandemic.

Man walks in mask and with stroller in front of mural in France
Image captionResearch indicates that one third of those infected have no symptoms

“Half of the people who are infected with the pandemic do not know this because they have no symptom or have a very mild symptom, such as a headache and runny nose, for example, and this is not necessarily associated with this disease. These people continue to circulate and transmit the virus ”, says Silva.

The epidemiologist Lúcio Botelho, professor at the Department of Public Health at the Federal University of Santa Catarina (UFSC), considers this index “scary”.

Especially since only 2.55% of the research participants said they had been tested for covid-19 with molecular tests, which are the ones that allow the diagnosis of the disease.

“Without being able to do mass tests, we have no way of knowing who is transmitting the virus or not. This means that isolation is fundamental, because it is the only way we have today to prevent this from happening, ”says Botelho.

Open questions

Finally, the Spanish study points out that, among people who had done a molecular test, 87% had antibodies against Sars-cov-2.

This is a good sign, because it points out that our body develops some form of protection against this new virus.

In the research, only the antibodies known with Igg were analyzed, which are those created so that the organism is able in the future to combat the same threat more efficiently.

Immunologist Renato Astray estimates that the rate of 13% who did not develop antibodies may have been caused by a diagnostic error, because the rapid tests used in this phase of the study give results with an accuracy rate of only 79%.

Indigenous child wearing a mask puts headdress on coffin in Brazil
Image captionLower index of children with antibodies intrigues experts

Astray says that it will only be possible to confirm or refute this hypothesis in the next stages of the research, when a type of laboratory antibody test will be carried out that has a greater accuracy, around 95%

More research will also be needed to understand whether this immune response is really effective.

“Having antibodies does not necessarily mean being protected, because this antibody needs to be of the neutralizing type to prevent the virus from infecting the cell,” says the immunologist.

Virologist Aguinaldo Pinto, professor at the Department of Microbiology, Immunology and Parasitology at UFSC, explains that this does not happen, for example, with the HIV virus.

“A person who has HIV has an enormous amount of Igg antibodies, but they are never neutralizing, and the patient develops AIDS if he does not receive treatment,” says Pinto.

Another important aspect is to check if this immunity is short or long term. The virologist says that even when we develop an antibody, it does not necessarily remain forever in the body.

“This happens with mumps, for example, which generates long-term immune memory, but not with rotavirus, which causes diarrhea in a child. The antibody against it lasts for a while and then disappears. We will only find out in which case the coronavirus fits over time ”, says Pinto.

More research will also be needed to understand an intriguing aspect of the data presented so far by the Spanish study.

The rate of participants with antibodies is quite different between age groups. The rates in children aged 0 to 9 years vary between 1.1% and 3% and are significantly lower than among the elderly, who have rates between 5.1% and 6.9%.

“What would be expected would be that most groups had the same antibody production,” says Pinto.

One possible explanation is that the immune systems of very young children are still forming, which would lead to less antibody production.

But this should also be seen in the elderly, because our immune system starts to deteriorate from the age of 60, which impairs its functioning, says Astray.

“Are the different levels because the children had less exposure to the virus or because they did not develop antibodies? This is a question that remains. ”

Source: https://www.bbc.com/portuguese/internacional-52685597

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