Coronavirus not the real killer: it’s the patient’s immune system
London, April 12, 2020 (AltAfrica)-The problem with such a fast and widespread pandemic as the novel coronavirus is that scientists and doctors only understand the virus and the disease it causes while in a state of flux. Knowledge changes almost daily and it’s often disseminated through hundreds of preliminary scientific reports that doctors on the ground might not have time to scour, busy as they are saving lives.
Some experts ponder whether scientists are going too fast in the well-intentioned race to understand the pandemic, causing more confusion than anything else.
Understanding COVID-19, an ‘unknown’ disease with multiple faces
- Half of those infected don’t develop symptoms, but are a vector of contagion
- Most patients have only mild symptoms
- In severe patients it is not the virus that kills, it is an uncontrolled reaction of the immune system that can damage most vital organs, a cytokine storm
- It’s not known what makes that some patients, regardless of their age, develop severe symptoms
- The virus can attack the nervous system. In some cases respiratory failure is related to neurological failure, not pneumonia
- It’s not certain when recovered patients stop being contagious
- There are doubts about how long immunity lasts after the disease
This constantly changing information plays a part in why we have been hearing different advice, sometimes contradictory, from the authorities, whether it be the convenience of using face masks or how to identify first symptoms.
Some still say “it’s just a little flu” in the face of evidence that demonstrates it is a deadly public health nightmare.
At the beginning of the epidemic we were told that cough and fever were the unequivocal signs that we could have contracted COVID-19. Now we know that the disease can cause a wide variety of symptoms and even no symptoms at all.
It is believed that about 50% of infected patients are asymptomatic – which has been one of the main factors in the lightspeed spread of the novel coronavirus.
Many precise details about the disease remain pretty much unknown. Doctors have learned to fight COVID-19 almost on a case by case basis even if now protocols are improving.
Here are some leads, given to Euronews by doctors working on the frontline, to better understand the disease, and why it is so dangerous for the population at risk and our health systems.
How does COVID-19 happen?
Roger Paredes, Head of the Infectious Diseases Section at Germans Trias i Pujol Hospital, near Barcelona, tells Euronews that there are three different stages of the infection for people developing COVID-19 symptoms:
- The viral phase: when the virus replicates very quickly within the respiratory system. Symptoms are similar to common flu and disappear spontaneously after 6 to 10 days (roughly). It is the case for about 80% of the patients.
- The pulmonary phase: The other 20% of the patients might develop a pneumonia. It’s a very specific type of pneumonia, attacking both lungs and causing respiratory distress.
- Severe phase: around 10% of the patients develop a “cytokine storm” an uncontrolled inflammatory response of the immune system which is causing most of the critical conditions and eventually, fatalities.
What’s the real killer?
Doctors on the ground report that severe cases don’t develop a high “viral load” (concentration of virus) but a cytokine storm syndrome.
“The cytokine storm is a problem we face quite often in intensive care” says Rafael Máñez, head of intensive care unit at Bellvitge Hospital, also close to Barcelona. Other infections and even some drugs can trigger it. “The problem is that we don’t have a treatment, neither against the virus nor for the inflammatory response” Máñez tells Euronews. “We only have supportive treatments, to protect the patient’s vital organs”. Doctors use respirators, or drugs to control blood pressure or corticoids to reduce inflammation.
Another lead is using drugs to block interlukin-6, a pro-inflammatory cytokine produced by the immune system.
He says cytokine storms do happen during the flu season, but patients admissions are gradual. “Due to the exceptional infection rates of COVID-19 we get more patients than we can manage”.
Máñez highlights a nuance in the consensus that having strong defences are better to cope with the disease “you don’t need a strong immune system but a balanced one” he states.
Dr. Paredes is leading a clinical study in cooperation with the US National Institute of Health using remdesivir. It will take three years.
Cytokine storms, an obscure syndrome
“The exact mechanisms of cytokine storms are pretty much unknown” says Paredes. “The inflammatory response is a natural immune system reaction. It’s necessary to repair cell damage. With normal pneumonia, germs damage the pulmonary tissue and the immune system generates an inflammatory response to stop it. The immune system ‘kills’ some cells to repair the damaged tissue. What is happening now with coronavirus is that instead of sending a few cells it’s sending tonnes of cells that generate an uncontrolled inflammatory response, not only in lungs but can be widespread in the body”.
Indeed, there have been reports of kidney, intestinal, or coronary damage. “I have a young patient with a myocarditis (inflammation of the heart muscle)” says Dr. Máñez.
It is believed that some of the patients experiencing intense headaches could suffer encephalitis (inflammation of the brain).
About 70% of our patients are older than 70, and between 10% and 15% are younger than 60 years old
Roger Paredes Head of infectious diseases unit at Germans Trias i Pujol Hospital
It is not known which factors predispose patients to develop the syndrome. Regarding COVID-19, age is very significant. “The key is to understand who are the most susceptible,” says Paredes “About 70% of our patients are older than 70, and between 10% and 15% are younger than 60 years old”.
Scientists believe genetics play a major role in the rare cases of young patients developing the syndrome.
When people of any age suffer a cytokine storm, degradation is really quick so it’s very important to identify the early signs, says Paredes.
According to Máñez, obesity can increase the chances of an inflammatory response.
COVID-19 can attack central nervous system
Research and experience on the ground show that the SARS-CoV-2 virus can attack the central nervous system. Dr. Paredes reports some patients in respiratory distress sometimes don’t feel the lack of oxygen or the pneumonia.
He suspects some patients enter in respiratory distress precisely because their nervous system is not managing to breathe properly. This has also been reported in some preliminary papers.
The loss of smell and taste frequently reported could also be linked to central nervous system in some cases, according to Paredes.
Doctors around the world are reporting cases of neurological manifestations suggesting the virus can breach into the central nervous system like blood clots, dizziness, confusion or convulsions. The hospital of the University of Brescia in Italy has opened a separate NeuroCovid unit to care for patients with neurological conditions, The New York Times reports.
A team from Wuhan, the initial epicentre of the pandemic has issued a preliminary paper reporting 36.4% of the 214 patients studied developed different degrees of neurological disorders. SARS-nCoV-2’s predecessors SARS and MERS also could make their way into our central nervous system.
All studies suggest these are rather rare cases but shouldn’t be underestimated.
And after the disease?
Even if scientists are beginning, gradually, to better understand the disease, many questions remain about the perspectives for recovered patients, like how long they will remain immune or the long term effects in their organs.
According to Roger Paredes, released patients in Spain spend two more weeks in quarantine at home before being tested again. It is currently under discussion for how long theses patients remain a vector of contagion for others. Current PCR tests are not 100% reliable to determine this. It will depend on antibody tests in large population samples.
While many governments are preparing their lockdown exit plans, the European Centre for Disease Control (ECDC) has warned that rushing in could lead to an upsurge and that, with the data in hand, no European country is prepared to lift movement restrictions and social distancing measures due to the difficulties in controlling cases.
“Before considering lifting any measures, member states should ensure that improved systems of testing and surveillance of the population and hospitals are in place to inform and monitor escalation/dis-escalation strategies and to assess the epidemiological consequences” says the ECDC.
Interestingly, despite scientific advances, staying home, soap and hygiene are the main barriers to the virus so far. “We were not aware. We had the feeling that with the knowledge we had this could not happen. With this crisis we will realise that we are very vulnerable,” summarises Dr. Rafael Máñez
Source: Euro News