Monday, May 18, 2020

Blood-thinning drugs can help save the lives of coronavirus patients by stopping dangerous clots forming on the lungs, British scientists discover

London specialists made the discovery after finding Covid-19 caused potentially deadly blood clots in the lungs of most patients who die.

NHS England will give hospitals new guidance on blood thinning, which may lead to the administration of higher doses for those who are critically ill.

Specialists at the Royal Brompton Hospital's severe respiratory failure service identified the clearest link yet between Covid-19 and clotting.

They used hi-tech dual energy CAT scans to take images of lung function in the worst patients - which found a lack of blood flow, suggesting clotting within the small vessels in the lung. 

This may explain why some patients die of lung failure through lack of oxygen in the blood, doctors told The Sunday Telegraph.

Low oxygen levels have been regularly recorded in Covid patients reporting no breathlessness.

Prof Openshaw, a specialist in experimental medicine at Imperial College London told the publication: 'This intravascular clotting is a really nasty twist that we haven't seen before with many other viruses.

'It does sort of explain the rather extraordinary clinical picture that is being observed with people becoming very hypoxic, very low on oxygen and not really being particularly breathless. That would fit with it having a blood vessel origin.'

As a result of the new evidence, clinical trials to test blood-thinning drugs are being fast-tracked as part of the Government's response to the pandemic. 

The new NHS England guidance is independent of the work, and is believed to have been issued on the advice of haematology specialists.

Doctors at the Royal Brompton said blood thinning medication should be used carefully and specialists have said treatment would need to 'start very early' to prevent clots forming.

Dr Brijesh Patel said she thinks the majority of patients will end up on 'significant therapeutic doses' of blood-thinning drugs as scientists learn more about the disease, and if implemented properly they will save lives.   



Delaying herd immunity is costing lives

The current lockdown is protecting the healthy instead of the vulnerable.

Climate scientists are frustrated by people who do not believe in climate change. In epidemiology, our frustration is with anti-vaxxers. Most anti-vaxxers are highly educated but still argue against vaccination. We now face a similar situation with ‘anti-herders’, who view herd immunity as a misguided optional strategy rather than a scientifically proven phenomenon that can prevent unnecessary deaths.

Because of its virulence, wide spread and the many asymptomatic cases it causes, Covid-19 cannot be contained in the long run, and so all countries will eventually reach herd immunity. To think otherwise is naive and dangerous. General lockdown strategies can reduce transmission and death counts in the short term. But this strategy cannot be considered successful until lockdowns are removed without the disease resurging.

The choice we face is stark. One option is to maintain a general lockdown for an unknown amount of time until herd immunity is reached through a future vaccine or until there is a safe and effective treatment. This must be weighed against the detrimental effects that lockdowns have on other health outcomes. The second option is to minimise the number of deaths until herd immunity is achieved through natural infection. Most places are neither preparing for the former nor considering the latter.

The question is not whether to aim for herd immunity as a strategy, because we will all eventually get there. The question is how to minimise casualties until we get there. Since Covid-19 mortality varies greatly by age, this can only be accomplished through age-specific countermeasures. We need to shield older people and other high-risk groups until they are protected by herd immunity.

Among the individuals exposed to Covid-19, people aged in their 70s have roughly twice the mortality of those in their 60s, 10 times the mortality of those in their 50s, 40 times that of those in their 40s, 100 times that of those in their 30s, and 300 times that of those in their 20s. The over-70s have a mortality that is more than 3,000 times higher than children have. For young people, the risk of death is so low that any reduced levels of mortality during the lockdown might not be due to fewer Covid-19 deaths, but due to fewer traffic accidents.

Considering these numbers, people above 60 must be better protected, while restrictions should be loosened on those below 50. Older people who are vulnerable should stay at home. Food should be delivered and they should receive no visitors. Nursing homes should be isolated together with some of the staff until other staff who have acquired immunity can take over. Younger people should go back to work and school without older coworkers and teachers at their sides.

While the appropriate magnitude of countermeasures depends on time and place as it is necessary to avoid hospital overload, the measures should still be age-dependent. This is how we can minimise the number of deaths by the time this terrible pandemic is over.

Among anti-herders, it is popular to compare the current number of Covid-19 deaths by country and as a proportion of the population. Such comparisons are misleading, as they ignore the existence of herd immunity. A country much closer to herd immunity will ultimately do better even if their current death count is somewhat higher. The key statistic is instead the number of deaths per infected. Those data are still elusive, but comparisons and strategies should not be based on misleading data just because the relevant data are unavailable.

While it is not perfect, Sweden has come closest to an age-based strategy by keeping elementary schools, stores and restaurants open, while older people are encouraged to stay at home. Stockholm may become the first place to reach herd immunity, which will protect high-risk groups better than anything else until there is a cure or vaccine.

Herd immunity arrives after a certain still unknown percentage of the population has acquired immunity. Through long-term sustainable social distancing and better hygiene, like not shaking hands, this percentage can be lowered, saving lives. Such practices should be adopted by everyone.

Social distancing that cannot be permanently sustained is a different story. Some people will eventually be infected, and for every young low-risk person avoiding infection, there will ultimately be roughly one additional high-risk older person that is infected, increasing the death count.

Anti-vaxxers do not suffer the consequences of their beliefs, as they are protected by the herd immunity generated by the rest of us. Neither will the anti-herders, many of whom can afford to isolate themselves from Covid-19 until natural herd immunity is achieved by others. It is older and working-class people that disproportionately suffer from the current approach, becoming infected and thereby indirectly protecting much lower-risk college students and young professionals who are working from home.

The current one-size-fits-all lockdown approach is leading to unnecessary deaths. Protecting older people and other high-risk groups will be logistically and politically more difficult than isolating the young by closing schools and universities. But we must change course if we want to reduce suffering and save lives.



How coronavirus spreads, and why some are spared – and others not

New study analysing dozens of actual Covid-19 clusters from around the world shows enclosed spaces are hotbeds of the virus

Risk of coronavirus infection is much higher within households or other enclosed environments in which contact is close and sustained

Almost every day now, a new study is published that shines light on the way in which the new coronavirus is spread. It will be years before the precise dynamics of transmission are nailed down, but the broad outline of how the disease moves is becoming clear.

The latest findings come not from epidemiological estimates but from analysis of dozens of actual Covid-19 clusters unpicked by contact and trace teams from around the world. These studies are like a forensics report from a crime scene. While a good psychological profiler can point detectives in the right direction, the CSI team gives them the smoking gun.

An analysis of such studies was recently posted on Twitter by Dr Muge Cevik, an infectious diseases clinician and researcher from St Andrews University. It was promoted by Sir Jeremy Farrar, the head of the Wellcome Trust and a member of the Scientific Advisory Group for Emergencies (Sage). "If you read one thread,make it this one," Sir Jeremy said.

Dr Cevik starts with a big Chinese study that traced 2,147 close contacts of 157 confirmed Covid-19 cases. The overall infection rate was six per cent, but it was much higher among friends (22 per cent) and family members (18 per cent). In terms of location, the main risk factors were homes (13 per cent) transport (12 per cent) and dinner and entertainment (seven per cent).

Broadly similar findings emerge in several other papers. Risk of infection is much higher within households or other enclosed environments in which contact is close and sustained. In the outdoors, it falls to something in the 0-5 per cent range.

Transmissibility also appears to be impacted by age and the type of relationship people have with one another. A Chinese study of 392 contacts of 105 confirmed cases found that the attack rate in children was just four per cent within the home, compared with 17.1 per cent in adults, for example. The infection of spouses was super high, at 28 per cent.

Emphasising the link with age, another study found that household members over 60 were much more likely to become infected (18 per cent) than those under 20 (five per cent).

Children, it seems, are not only better able to resist the infection within the home but also less likely to bring it back with them. A study, funded by the Australian Research Council, of 31 household clusters including children found that only 10 per cent had been sparked by children.

"Whilst SARS-CoV-2 can cause mild disease in children, the data available to date suggests that children have not played a substantive role in the intra-household transmission of SARS-CoV-2," said the authors.

Using these and other studies, Dr Cevik concludes that they suggest (not prove) the following:

Close and prolonged contact is required for transmission of the virus.

Risk is highest in enclosed environments such as houses, care facilities, public transport, bars and other indoor spaces where people congregate.

Casual, short interactions are not the main driver of the epidemic.

Susceptibility to infection increases with age.

Dr Cevik does not look at how the virus passes from person to person, but plenty of other research suggests it moves in droplets expelled from the infected. Droplets may land directly on the mucus membranes of others (eyes, nose, mouth) or indirectly via shared surfaces (plates, desks, doorknobs). If the virus were truly airborne, household infection rates would almost certainly be far above 20 per cent.

Is this good or bad news for the Prime Minister, who is working hard this weekend on the UK exit strategy? And what sort of policies might it point to?

On the upside, it suggests lockdown can be relaxed with much less risk in outside spaces. In truth, Britain has been more liberal on this from the start than places like Spain, France and Italy, and the evidence suggests it can almost certainly go further. The trick will be to find mechanisms to stop people from inadvertently forming crowds by turning up at the same places at the same time.

The evidence also points to the power of good hygiene. Household attack rates are high, at 20 per cent – but that leaves 80 per cent who escape despite living under the same roof. There is some evidence that UK infections started to fall ahead of lockdown because of hand-washing and other hygiene messages. These should almost certainly be ramped up again, and extended. Think hand-cleansing facilities at every doorway, public or private.

On the downside, our winters are cold and wet, forcing us to congregate inside. Dr Cevik says this points to the need to "redesign our living and working spaces and rethink how to provide better, ventilated living and working environments for those who live in deprived and cramped areas". That will be a hard task, but an essential one.

It is winter that the Government will be most worried about. It can give us some outdoor freedom now, but it knows that won't mean much beyond September. The NHS also comes under much greater strain in winter, and Covid-19 symptoms will become harder to detect when mixed with flu and winter sniffles.

Ministers will therefore want to do everything possible now to drive down the virus to levels at which contact tracing teams can keep it in abeyance before winter arrives. Anything else and they risk a second major outbreak two to three months after the nights draw in.



For more blog postings from me, see  TONGUE-TIED, EDUCATION WATCH INTERNATIONAL, GREENIE WATCHPOLITICAL CORRECTNESS WATCH, AUSTRALIAN POLITICS, and Paralipomena (Occasionally updated), A Coral reef compendium and an IQ compendium. (Both updated as news items come in).  GUN WATCH is now mainly put together by Dean Weingarten. I also put up occasional updates on my Personal blog and each day I gather together my most substantial current writings on THE PSYCHOLOGIST.

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1 comment:

mmacg said...

OK, so just how infective is this virus?
If 72% of spouses of infected persons do not get infected despite presumably close and sustained and often intimate contact, is it not possible that a large proportion and possibly a ajority of the population is actually naturally immune to infection?