A Brazilian city where the dead bodies of coronavirus victims had to be piled up in refrigerated trucks may have reached herd immunity against the disease without a lockdown, scientists say.
Manaus has witnessed a sharp but unexplained fall in Covid-19 cases, deaths and hospitalisations — despite a lack of control measures, suggesting the coronavirus has naturally fizzled out.
The city, situated in the middle of a rainforest, was ravaged by the coronavirus at the start of the pandemic. It made international headlines four months ago when drone images captured bulldozers digging mass graves for Covid-19 victims.
Hundreds of bodies were stored in refrigerated trucks in scenes described by the city’s mayor as a ‘horror movie’.
But unlike the majority of Asia and Europe, the city never imposed a lockdown, strict social distancing rules or enforced face masks. Brazil’s president was a vocal critic against the measures, which have crippled economies but saved lives.
Jarbas Barbosa da Silva, assistant director of the Pan American Health Organisation, claimed the peak of the outbreak was very strong, which may have produced some kind of ‘collective immunity’.
But he added the city, in the Amazonas state, had ‘paid a very large price’. Figures show it has suffered 3,300 deaths among the 1.8million residents — the equivalent of one in 500 residents being killed by the virus.
Herd immunity would mean a country is no longer at risk of Covid-19. However, to achieve it, up to 70 per cent of the population needs to have had the virus, which in turn would see millions of people die. Scientists still don’t know the death rate of the disease for certain but believe it kills around 0.6 per cent of all patients, most of whom are elderly.
Brazil’s worst-hit city battled an outbreak that made world headlines four months ago when drone images captured bulldozers digging mass graves for Covid-19 victims. Pictured: An aerial view of the Parque Taruma cemetery in Manaus
Health workers wearing protective gear move a person’s body into a refrigerated truck at the Dr Joao Lucio Pereira Machado hospital in Manaus on April 24
Manaus has witnessed a sharp but unexplained fall in Covid-19 cases, deaths and hospitalisations — despite a lack of control measures, suggesting the coronavirus has naturally fizzled out. Graphs of new and total cases in Amazonas from coronavirus.app, using data from the Brazilian health ministry
Data shows the number of patients dying from Covid-19 in Amazonas has stabilised, after peaking in May with around 100 fatalities every day
Figures show Amazonas – in blue – hasn’t been hit as hard as Sao Paulo, in the south of the country. Some 116,000 cases have been confirmed in Amazonas
Brazil’s coronavirus outbreak is the world’s second most severe, after the US, with more than 3.6million cases and 115,309 deaths recorded since March.
But its outbreak is still rattling on, with Brazil registering 1,271 Covid-19 deaths and 47,134 new cases on Monday.
The Amazonas is one of hardest-hit states, with 116,579 cases and 3,588 reported deaths as of Tuesday. Most are in Manaus.
BRAZIL PRESIDENT’S SON GETS COVID-19
Brazilian Senator Flavio Bolsonaro, the eldest son of president Jair Bolsonaro, has tested positive for the novel coronavirus, according to a statement by Flavio’s spokesman.
Flavio has no symptoms of COVID-19 and is at home, it said, adding he has started taking chloroquine and azithromycin as part of a treatment against the virus.
President Bolsonaro is a big supporter of chloroquine, a drug used to treat malaria, despite the lack of solid evidence it works against the disease.
Bolsonaro himself caught the virus earlier, as well as his wife Michelle Bolsonaro and his youngest son, Jair Renan.
Advertisement
The city accounts for all of the intensive care units in Amazonas and 80 per cent of its specialised doctors, according to Bernardo Albuquerque, an infectious disease expert at Amazonas Federal University.
No formal lockdown was imposed on the city. Mask-wearing is not encouraged across the country.
Brazil’s president Jair Bolsonaro, who was infected himself, has dismissed the effects of the virus. He has described it as a ‘little cold’ and demanded an end to lockdown measures.
Many regional leaders ignored him and imposed their own quarantine measures.
Brazil’s State Public Prosecutor’s Office in Manaus tried to establish a lockdown to contain the pandemic in the city in April.
But a local judge denied the request, citing insufficient information, a report in the medical journal Nature Medicine states.
On May 6, the Legislative Assembly of the state of Amazonas approved a bill allowing the reopening of temples and churches, ‘non-essential’ retail stores opened on 1 June. Private schools reopened last month.
But despite this, Manaus has not seen cases increase like other countries that have relaxed Covid-19 restrictions on movement — including the UK and swathes of Europe.
There are close to zero ‘excess deaths’ and the city’s field hospital, built specifically for Covid-19 and once completely overwhelmed with patients, has been closed due to a lack of Covid-19 cases.
The Amazonas generally is recording around 780 new cases per day and 10 Covid-19 deaths. This compares to 2,700 cases and 50 deaths during the darkest days of the crisis at the end of May.
‘There isn’t a concrete explanation,’ Henrique dos Santos Pereira, a scientist at the Federal University of Amazonas, said.
‘Manaus is an interesting case indeed,’ Jarbas Barbosa da Silva, assistant director of the Pan American Health Organisation.
Mr Barbosa said that the decline in cases was gradual enough to suggest ‘a natural dynamic’ rather than the effect of public health initiatives.
He told The Washington Post: ‘The hypothesis — and this is just a hypothesis — is the peak we had in Manaus was very strong, and there was such widespread community transmission that it may have produced some kind of collective immunity.’
Mr Barbosa insisted, however, that Manaus had ‘paid a very large price’ and that the number of deaths ‘was a tragedy’.
Herd immunity occurs when enough of the population is protected from a disease because so many of them have been exposed to it — because they’ve already had it or have been vaccinated — that it cannot spread.
There is no indication that any country in the world has developed herd immunity yet, based on antibody studies.
Antibody studies are considered the most accurate way of calculating how much of the population has already been infected because millions of infected patients were not swabbed for the virus during the height of the crisis, either because of a lack of tests or because they had no symptoms.
In places severely battered by the disease, some infectious disease specialists have speculated that there is some level of protection.
According to The Times, testing in Manaus reveals that 20 per cent of people there have already had Covid-19.
But research has suggested that antibodies decline three months after infection — meaning only a fraction of true cases may have been spotted. And some people may never develop antibodies at all, so the true number of cases will always be a mystery.
Previously it’s been speculated 60 to 70 per cent of the population would need to suffer Covid-19 or be vaccinated to gain ‘herd immunity’ status.
But other modelling studies suggest as little as 10 to 20 per cent need to have had the virus.
The calculations account for swathes of people who are less likely to get infected. Immunity among the most socially active people could protect those who come into contact with fewer people, scientists say.
Funeral workers in protective gear carry the coffin of Nicolares Osorio Curico, who his relatives say died of the coronavirus disease, at the Nossa Senhora Aparecida cemetery in Manaus, April 16
A collective burial of people that have passed away due to the coronavirus disease is seen at the Parque Taruma cemetery in Manaus, Brazil, April 23
A burial taking place, attended by mourners and funeral workers in face masks, at an area where new graves have been dug at the Nossa Senhora Aparecida cemetery in Manaus, April 22
A series of coffins lie in a newly-dug grave at the Nossa Senhora de Aparecida cemetery in Manaus, April 22
WHAT IS HERD IMMUNITY AND WHICH COUNTRIES ARE PURSUING IT?
Herd immunity is a situation in which a population of people is protected from a disease because so many of them are unaffected by it – because they’ve already had it or have been vaccinated – that it cannot spread.
To cause an outbreak a disease-causing bacteria or virus must have a continuous supply of 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 encountered it before, either by having the illness in the past or through a vaccine.
When a virus or bacteria enters the body the immune system creates substances called antibodies, which are designed to destroy one specific type of bug.
When these have been created once, some of them remain in the body and the body also remembers how to make them again. Antibodies – alongside T cells – provide long-term protection, or immunity, against an illness.
If nobody is immune to an illness – as was the case at the beginning of the coronavirus outbreak – it can spread like wildfire.
However, if, for example, half of people have developed immunity – from a past infection or a vaccine – there are only half as many people the illness can spread to.
As more and more people become immune the bug finds it harder and harder to spread until its pool of victims becomes so small it can no longer spread at all.
The threshold for herd immunity is different for various illnesses, depending on how contagious they are – for measles, around 95 per cent of people must be vaccinated to it spreading.
For polio, which is less contagious, the threshold is about 80-85 per cent, according to the Oxford Vaccine Group.
WHICH COUNTRIES ARE PURSUING HERD IMMUNITY?
Herd immunity is considered a controversial route for getting out of the pandemic because it gives a message of encouraging the spread of the virus, rather than containing it.
When UK Government scientists discussed it in the early days of the pandemic, it was met with criticism and therein swept under the carpet.
The Chief Scientific Adviser Sir Patrick Vallance said at a press conference on March 12, designed to inform the public on the impending Covid-19 crisis: ‘Our aim is not to stop everyone getting it, you can’t do that. And it’s not desirable, because you want to get some immunity in the population. We need to have immunity to protect ourselves from this in the future.’
Sir Patrick has since apologised for the comments and said he didn’t mean that was the government’s plan.
In a Channel 4 documentary aired in June, Italy’s deputy health minister claimed Boris Johnson had told Italy that he wanted to pursue it.
The Cabinet Office denied the claims made in the documentary and said: ‘The Government has been very clear that herd immunity has never been our policy or goal.’
Meanwhile, unlike most European nations, Sweden never imposed a lockdown and kept schools for under-16s, cafes, bars, restaurants and most businesses open. Masks have been recommended only for healthcare personnel.
Sweden only introduced a handful of restrictions, including banning mass gatherings and encouraging people to work and study from home.
Dr Anders Tegnell, who has guided the nation through the pandemic without calling for a lockdown, claimed on July 21 that Sweden’s strategy for slowing the epidemic, which has been widely questioned abroad, was working.
Dr Tegnell, who previously said the ‘world went mad’ with coronavirus lockdowns, said a rapid slowdown in the spread of the virus indicated very strongly that Sweden had reached relatively widespread immunity.
‘The epidemic is now being slowed down, in a way that I think few of us would have believed a week or so ago,’ he said.
‘It really is yet another sign that the Swedish strategy is working.’
At the time Sweden’s death toll was 5,646 which has now reached 5,814. But when compared relative to population size, it has far outstripped those of its Nordic neighbours.
Advertisement
Manaus was one of the first cities to be hit badly by coronavirus in Brazil, which experts partly blamed on the large number of indigenous communities living there.
Amazonas has more indigenous people than any other state in Brazil, and they are considered to be more vulnerable to diseases brought in from outside because their immune systems have not been exposed to them.
It can take days for people in extremely vulnerable indigenous communities to reach health centres because the Amazonas state is so big.
Historically, indigenous communities have been devastated by viruses they cannot cope with.
In April, shocking aerial images of mass graves in Manaus caused alarm around the world.
At a cemetery called Parque Taruma, crews dug holes in the earth to make mass graves for coronavirus victims. Under orders from local officials, no more than five relatives were allowed to gather to say goodbye.
The mayor of Manaus, Virgilio Neto, said the hundreds of coronavirus deaths was ‘a scene out of a horror movie’.
He said his city was ‘no longer in a state of emergency but rather of absolute calamity’ after the daily death rate shot up because of the pandemic.
‘We are working hard to bury people. We have had gravediggers fall ill with coronavirus. Some will not make it,’ said the mayor. ‘This is a really, really tough fight.’
Mr Neto was one of the harshest critics of Mr Bolsonaro’s handling of the pandemic in Brazil, calling him an ‘indirect murderer’ in May.
He had pleaded with the federal government on numerous occasions to help contain the spread of the coronavirus in Manaus.
But on 8 July, President Bolsonaro vetoed measures to protect indigenous peoples from Covid-19, such as free distribution of hygiene and cleaning materials and the disinfection of villages.
According to Mr Neto, the health system collapsed in April, as did the city’s mortuaries and cemeteries, representing the collapse of almost an entire state.
But the city’s devastation during the first wave of Covid-19 may mean it is more prepared if a second one hits, some scientists believe.
Others fear Manaus is heading towards a devastating second wave.
Lucas Ferrante, of the Instituto Nacional de Pesquisas da Amazônia, Manaus, says if a second wave of the pandemic in Amazonia is to be avoided, effective measures such as closing schools and non-essential services need to be implemented immediately.
This is because so few people are known to have developed immunity to the virus, which is still circulating, albeit at low levels, and could easily spread again.
In a paper published in Nature Medicine on August 7, Mr Ferrante and colleagues said: ‘Unfortunately, the general level of activity in the streets and commercial establishments of Manaus has returned to nearly normal despite the fact that the bulk of the population has no known immunity the virus.’
They claimed cases in Amazonas increased by 4,951 per cent and confirmed deaths had increased by 2,069 per cent between 17 April and 20 July as a result of failing to implement social distancing and domestic travel at the start of the pandemic.
Many other cities around the globe that were once devastated by coronavirus have begun to reopen but some appear to have avoided a spike in cases.
Some experts speculate this is because the population has herd immunity, which either stops people catching the coronavirus in the first place, or at least reduces the severity of the disease.
Some epidemiologists hypothesise that parts of London and New York have already achieved ‘substantial immunity’.
Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, told the New York Times: ‘I’m quite prepared to believe that there are pockets in New York City and London which have substantial immunity.
‘The reason people think it might be lower is that it’s not the case that everyone is equally likely to be infected by a transmissible disease,’ he told DailyMail.com.
‘If you go through the naturally infectious process, you are going to generate immunity in the people most likely to be exposed, by definition.’
In other words, groups like essential workers and people living in multi-generational homes are most likely to have been outside of their homes early in the pandemic, making them most likely to have already been infected and to have developed immunity.
The same is said by health officials in highly-dense areas like India’s Mumbai and Delhi, where studies have shown up to a quarter of people have antibodies against the disease.
Swedish health experts also claim to have achieved a level of herd immunity while abstaining from a lockdown.
Unlike most European nations, Sweden kept schools for under-16s, cafes, bars, restaurants and most businesses open. Masks have been recommended only for healthcare personnel.
Sweden only introduced a handful of restrictions, including banning mass gatherings and encouraging people to work and study from home.
Dr Anders Tegnell, who has guided the nation through the pandemic without calling for a lockdown, claimed on July 21 that Sweden’s strategy for slowing the epidemic, which has been widely questioned abroad, was working.
At the time Sweden’s death toll was 5,646 which has now reached 5,814 more than a month later.
But when Sweden’s death toll is compared relative to population size, it has far outstripped those of its Nordic neighbours.
Dr Tegnell, who previously said the ‘world went mad’ with coronavirus lockdowns, said a rapid slowdown in the spread of the virus indicated very strongly that Sweden had reached relatively widespread immunity.
‘The epidemic is now being slowed down, in a way that I think few of us would have believed a week or so ago,’ he said.
‘It really is yet another sign that the Swedish strategy is working.’
Link nguồn : https://www.dailymail.co.uk/news/article-8665475/Brazilian-city-Manaus-dead-bodies-piled-refrigerated-trucks-herd-immunity.html
