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This image shows SARS-CoV-2 (yellow), the virus that causes COVID-19. Image: EPA
What we don’t know yet: seven open questions about the corona virus
Corona’s investigation is in full swing. Many questions are still open, especially regarding immunity.
A viral illness is not a current act that takes place at a certain time. It is an interaction between the virus and the immune system that can be time consuming. We know pretty well about the “technical side” of the virus. We have genetically sequenced it, we know its phylogenetic history (how it came about), we know very well how it works in terms of molecular biology.
>> Corona Virus: all the news live
What we know less well are the responses of the immune system. Since they don’t happen right away, they take time.
Can you get infected twice?
The fact that there are people who have survived Covid-19 shows that our immune system can cope with the pathogen. We do not yet know whether a recovered patient is now permanently protected against the disease. Stories of reinstated patients should be treated with caution. Components of the virus (RNA) are known to remain in the body for a long time (up to two to three weeks) after recovery and react to the gene test. It has not been shown if you can get sick again or infect someone.
The summary of the situation in Switzerland:
Are you immune after a recovery?
So far there are 7 beta corona viruses that can infect humans. Only the last three (Sars-1 and Sars-2 and Mers) trigger serious illness. The others are the most common causes of a runny nose after rhinoviruses. Antibodies have been found in the blood of all those that have occurred to date. The recovered one became immune. By analogy, this is supposed to be the case with Sars-CoV-2 as well. 99 percent of Covid-19 patients developed antibodies, but some only very few. After all, an experiment with monkeys showed that the animals were protected against a second infection after a first infection and no longer developed symptoms.
How long does immunity last?
You are immune to measles for life. Other viruses do not cause immunity at all, you can get the same cold several times in the same winter. In Sars and Mers patients, the antibodies could still be detected in the blood two to three years after infection. Harmless corona viruses also cause immunity, but not for long: with OC43 and HKU1, immunity lasted for up to 40 to 45 weeks. We do not know how long Sars-CoV-2 immunity will last. You will see that then.
Corona virus: the situation worldwide:
Is there partial immunity?
The body’s immune system is multi-level and versatile. Depending on where the virus attacks, the answer is different. This can lead to partial immunities, which can also take different periods of time.
Are there immunities of different lengths?
Sometimes the antibodies disappear from the blood, but immunity persists. So-called memory cells take on the task of reacting immediately when a virus appears. There are memory B and T cells. B cells make antibodies, protein molecules, that envelop the virus and make it harmless; T cells cause infected cells to die. That is the case with Sars. However, the response of B cells that respond to the N protein that surrounds the viral RNA lasts less time.
Why memory cells develop in some pathogens and not others is unclear. The duration of immunity could also be related to the severity of the disease. Because with mild symptoms there are no traces in the immune memory. Most of the studies in Sars-1 and Sars-2 have dealt with seriously ill hospitalized patients.
What are you dying of?
Sars-CoV-2 causes severe pneumonia. When the lungs can no longer supply the body with enough oxygen, organ failure occurs. Many victims of Covid19 die from cardiovascular arrest. The virus can also attack other organs. The ACE2 receptor is not only present in the lungs. At the beginning of the epidemic, autopsies were largely avoided. Pathologists noted that many patients died of thrombosis and (pulmonary) embolism. This may mean that the virus also affects blood clotting. Some patients could have been saved with anticoagulants.
How do you control violent immune reactions?
Symptoms of the disease, such as fever, are warning signs that activate the innate immune system. The innate immune system causes inflammation locally to request help from the body. Cytokines, the messenger substances, are sometimes over-formed. Then a so-called “cytokine storm” occurs. The immune system builds up through cytokines that also attack immune cells. The problem is no longer defending against the virus, but your own immune system. Successful therapy must also control the immune system. This also applies to vaccination.
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