How physical distance works and saves lives

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How physical distance works and saves lives

This is a series of regular updates from Irish Times Environment & Science editor Kevin O’Sullivan on scientific initiatives and developments regarding the coronavirus. Previous editions can be found here.

Play the antibody card

The war against Covid-19 has three components: a longer-term race to produce an effective vaccine in large populations; generation of treatments (antivirals) to be deployed in the meantime and use of anti-coronavirus antibodies called immunoglobulins. These are proteins produced by plasma cells in the bloodstream and used by the immune system to neutralize pathogens such as viruses.

The presence of antibodies confirms the infection, so testing for their presence can be a valuable indication of immunity, especially for those working in healthcare.

In addition, antibodies have great potential as a treatment. Like the global race to produce a vaccine, many laboratories are working to develop rapid antibody tests, some of which may even be self-test kits.

Meanwhile, New York health officials plan to start collecting plasma from people who have recovered and injecting the antibody-rich fluid into patients who are still battling the virus in clinical trials. Known as convalescent plasma, it has been used for centuries and was deployed during the terrible flu pandemic of 1918, but not in recent decades.

Some experts say that the treatment, although somewhat primitive, may be the best hope of fighting the coronavirus until more sophisticated therapies are developed, which could take months.

Infusions of convalescent plasma were associated with milder symptoms and shorter hospital stays for some patients during the 2002 SARS epidemic, and early reports from China suggest it may also be effective in mitigating the effects of Covid-19.

The treatment is not without risks. There is a danger in giving a patient the wrong type of blood or inadvertently transmitting other pathogens during a transfusion, but advances in safety over the past decades have made side effects rare. As a first step, it will be offered to seriously ill patients. Once proven to be safe and effective, it will likely work best with patients before the symptoms get too severe.

The US pharmaceutical company Regeneron, which has a large “industrial facility and a product supply facility” employing 1,000 people in Limerick, has also identified hundreds of antibodies that could treat or prevent the coronavirus.

He confirmed his “plans to launch large-scale manufacturing by mid-April with antibody cocktail therapy, with potential to enter human clinical studies in early summer.”

“We don’t disclose which products are made where,” said a spokesperson – although she is recruiting specialized staff for her Limerick plant. Longer-term antibody tests will also help researchers understand the length of immunity to the virus; a key question for any future vaccine.

The science of physical remoteness

The tip of the Covid-19 lance is getting closer and closer. That’s when it will cause its maximum toll – the top of this dreaded case curve.

At this stage of the pandemic with cases that jump daily, physical distance within the community is of crucial importance; hence the new restrictions extended with a tightening of this key measure.

Obviously, this fits with hand washing strategies; self-isolate in case of symptoms, cough / sneeze into the elbow; and “test, test, test”.

Transmission route: Physical distance is necessary because Covid-19 is mainly spread from person to person, i.e.

– between people in close contact (within a radius of about 2 meters);

– By respiratory droplets carried in the air produced when an infected person coughs or sneezes.

These droplets can land in the mouth or nose of nearby people or possibly be inhaled into the lungs.

Justify the approach: Physical distance is not a theoretical precaution, it is a scientifically justified action based on mathematics, the understanding of social models and medical knowledge (epidemiology). It revolves around determining the r0 (pronounced “r-nil”) value of an infectious disease.

The r0 for Covid-19 is estimated at 2.5. Thus, a typical infected person will transmit it to 2.5 – between two and three people – during the period when they are infectious. Without control, a single case would result in 1000 cases after four weeks.

The objective is to reduce this figure below one. At this point, the disease stops spreading; the typical infected person does not pass the virus on to anyone else before recovering.

Complex consideration of the length of time the virus remains infectious; cultural considerations (the extent to which people have physical contact), transmission data, and immunity / susceptibility considerations are all part of the calculation of r0.

Key actions with Covid-19: All things considered, make sure it is less likely to spread to other people, by seeing less of it, and by reducing the chance during an interaction that the disease will pass to you – or from you to another. other person – are essential community actions. This is what forces the r0 down in this case. So we go back to the five-step strategy, including physical distance.

The proof: This is where contact tracing comes in handy, that is, determining who an infected person has been in contact with – when they were likely to be infectious – and ensuring self-isolation.

Irish actions (notably physical distance) carried out so far confirm that personal contacts have been reduced from 20 to 5, and have recently been confined to households.

That said, given the current trajectory of cases and deaths, public health experts say a further 75% reduction is needed to ensure the curve is forced. It is therefore back to the physical distance in knowledge that it works and saves lives.

Reasons for optimism

– Warning signs: Researchers confirm the distinct features of SARS-CoV-2 (the medical term for the virus) and the main differences from influenza. It is very stable and does not molt very much, that is, it changes its genetic mixture as it spreads. On the other hand, the flu is like a pack of cards (made up of genetic parts) which mix each year. So there is a good chance of generating an effective Covid-19 vaccine, while the annual flu vaccine is the best choice of the best immunologists, virologists and epidemiologists.

– The scale of human decency: Communities are mobilizing to help the most vulnerable in their localities. Equally impressive is the work of industry and academia to help healthcare professionals. DCU’s Nano Research Facility is changing operations to make disinfectants, and the Trinity’s Biomedical Sciences Institute has collected all of its gloves, gowns and masks and sent them to St James’s Hospital down the road. These actions are replicated across the country and save lives.

– A breach of hope on the Italian front: There are tiny signs that the infection rate in Italy is moderating, despite its appalling and appalling death toll. It can simply be data blips. However, it suggests that the overall rate of increase is slowing; as if the pandemic is losing momentum inside a country where it has nowhere to go. Ireland cannot relax its reduction efforts, as the increase in cases here shows no indication, but we can avoid the same fate as Italy.

@KOSullivanIT