March 2022 Estimated reading time 15 min.
The SARS-CoV-2 coronavirus continues to keep the pandemic going. However, both vaccinations and new viral variants have significantly changed the mix. Even more than before, this means: A coronavirus infection can mean completely different things to individuals. Some will never notice an infection. Many fall ill mildly. Recover quickly. But others can expect a difficult, protracted course – even death if things go badly. This article explains the different symptom courses.
COVID-19 comes in many forms
COVID-19 is not comparable to other diseases. Two people who become infected with the SARS-CoV-2 coronavirus often have very different courses of the disease. While one person may have already recovered before he has even realized his infection, another person may become seriously ill. "Symptomless" meets "in mortal danger". And both had the same virus.
This difference has been further exacerbated by vaccinations and new viral variants – for example, the delta and omicron variants. While all Corona vaccines licensed in Europe have been shown to protect against severe disease, unvaccinated adults may be affected by new viral mutations even more than before.
In the case of the delta variant (B.1617.2), this means not only an increased transmissibility compared to the original virus as well as the alpha variant (B.1.1.7). Rather, B.1617.2 possibly also associated with increased illness severity and thus more hospitalizations among the unvaccinated [1, 2].
The Omicron variant (B.1.1.529), on the other hand, due to its large number of mutations, is characterized by being able to overcome the antibodies easier to escape. Thus, it succeeds in displacing other variants. Data on disease severity are only preliminary, but suggest milder courses in some cases.
The "scissors" of possible courses thus diverge even further.
The most common symptoms in the ranking
In March 2020, the disease still resembled a mystery. The reports were overwhelming, but no one could really imagine what was threatening them at that time. However, we now know considerably more. Quite a few people have fallen ill or know sufferers personally. One has coughed, the other has breathed heavily. And some got away without any symptoms at all.
Thanks to studies, the frequencies of the different symptoms have been better analyzed and understood over time. Accordingly, between 15 and 45 % – i.e. on average one in three – of all infected persons remain without symptoms. After vaccination, this proportion can be even higher [3, 4].
Among infected individuals who become symptomatic [5, 6, 7]:
– 42 – 50% cough, – 26 – 43% fever, – ~ 36% aching limbs, – ~ 34% headache, – ~ 29% shortness of breath, – ~ 20% sore throat, – ~ 19% diarrhea, – 10 – 31% runny nose, – 10 – 19% smell or taste disturbances, – ~ 12% nausea or vomiting.
Other symptoms may include loss of appetite, weight loss, abdominal pain, abdominal tenderness, red eyes, skin rash, lymph node swelling, drowsiness and sleep problems, depressed mood, confusion, memory impairment, and loss of consciousness [5, 8].
The extent to which the omicron variant makes certain symptoms more likely or less likely is currently still the subject of investigation. Data, according to which it causes increased fatigue but less fever, are currently still based on far too small case numbers. Definitive statements can therefore only be made here with a time lag.
Incubation period: from infection to first symptoms
The so-called incubation period describes the time span from the moment of infection to the appearance of the first symptoms. This time varies for different infectious diseases – but also from person to person [9, 10].
In the case of the SARS-CoV-2 coronavirus, symptoms can appear 2 to 14 days after contact with the virus, but mostly after 5 to 6 days. In almost all corona infected persons with symptoms, however, these appear at the latest after 10 to 14 days [7, 9, 11].
In the case of SARS-CoV-2, however, transmission of the virus to others is also possible during the incubation period, i.e. before the onset of symptoms. This is what makes effective containment so difficult and the virus thus so successful [12].
From mild to life-threatening
According to studies to date, the average course of the disease is estimated as follows [13, 14, 15]:
Here, severe means that the affected person has shortness of breath as well as limited oxygen supply due to extensive lung involvement. In the life-threatening courses, there is pulmonary failure, circulatory failure (also called shock), or simultaneous failure of several organs [14].
When scientists speak of "mild", this also includes unpleasant courses of the disease with, for example, fever and a pronounced feeling of illness.
Of those with COVID-19 who are hospitalized for their symptoms, up to one in five will die. One in eight to four hospitalized COVID patients must be ventilated [14, 16, 17].
Even in infected individuals with a severe course, the disease often begins insidiously. Thus, after symptom onset, it takes an average of about 4 days for the person to be hospitalized with worsening symptoms. COVID-19 patients spend an average of 9 to 10 days there. Those who have to go to the intensive care unit because of severe discomfort spend an average of 5 days there – those who need ventilation even 10 days [18, 19].
Time intervals from SARS-CoV-2 infection to hospitalization, intensive care unit and other
In cases of confirmed SARS-CoV-2 infection, the mortality rate is estimated to be between 2 and 5%. However, since many infections go undiagnosed, mortality is probably more likely to be between 0.15 and 1% of all infected individuals. However, there are also many arguments why the number could be higher. In any case, mortality data looking at individual age groups are much more informative [14, 20, 21]. In Germany, men. Women are affected about equally often. However, on average, men are more severely affected by COVID-19 and, according to studies, die from the disease about twice as often as women [5, 16]
At present, no binding statements can be made on the course of the disease in the case of infection with the Omikron variant. First reports from doctors in South Africa as well as smaller case studies indicate an overall milder course of the disease. However, this may simply be due to the fact that South Africa has a comparatively young average age and the infestation was already high in earlier corona waves.
Information on the typical course of COVID-19 in children can be found at here.
Severe course: What to expect?
Severe and life-threatening courses together account for nearly one-fifth of all confirmed SARS-CoV-2 infections [14, 15].
Even in infected patients with a severe course, the disease often starts insidiously. For example, after the onset of symptoms, it takes about 4 to 7 days for the affected person to experience shortness of breath [18, 19, 22].
The following symptoms may occur in severe SARS-CoV-2 courses [15, 23, 24]:
Pneumonia – So-called pneumonia leads to parts of the lungs no longer being able to be properly ventilated. The consequence is a restricted oxygen supply to the body.
Pulmonary failure – Acute respiratory distress syndrome (ARDS) is a severe impairment of lung function in response to damaging stimuli such as severe pneumonia. Affected individuals have a poor prognosis despite artificial ventilation.
Formation of blood clots – So-called thrombi can form more frequently in the blood. The small blood clots can clog blood vessels and even flow with the blood flow – as so-called Embolism – be washed into various parts of the body such as the legs, lungs and brain. Oxygen deficiency of the affected region is the result.
Heart failure – In severe cases in particular, cardiac arrhythmias, damage to the heart muscle and associated functional disorders or even circulatory failure can occur.
Renal failure – This can occur as a complication in severely ill COVID patients. Sometimes affected patients have to be treated with a kidney replacement procedure known as dialysis.
Excessive immune reactions – In some affected individuals, there is a persistent exaggerated response of the immune system, which is detectable in the laboratory. This response is associated with a poor prognosis. In severe COVID-19 courses, the body is severely weakened. Thus more susceptible to further pathogens such as bacteria or fungi. The SARS-CoV-2 coronavirus also seems to affect the nervous system, according to studies to date. Triggering various neurological disorders in the process.
How deaths have evolved since the pandemic began
When what ends: symptoms, risk of infection, virus detection and recovery
Corona infected people can be contagious to others, whether symptoms are present or not. In the case of persons who become symptomatic at a later stage, it is also possible to infect other people even before the symptoms have appeared [25].
At the same time, the risk of transmission seems to be highest around the onset of symptoms. In corona-infected persons with a functioning immune system, the probability of transmission then decreases again as the disease progresses. On the other hand, in people with a severe course, the risk of infection to others is increased, even in the longer term [26].
Corona infection is detected in the laboratory using a polymerase chain reaction (PCR). This test usually provides reliable information about whether a person is infected and thus contagious to others [27, 28].
However, the test may be falsely negative in patients in whom the infection has progressed to pneumonia or ARDS. In these cases, the infection is no longer detectable by throat swab. In this case, a sample must be taken from the lower respiratory tract to be sure [27] .
Conversely, genetic material from the virus may still be detectable by PCR weeks after the disease, without the virus still replicating or the person being infectious. However, according to studies, in individuals with a mild course in whom symptoms have resolved, infectious virus is usually no longer detectable [26, 29].
How long am I contagious with a booster vaccination?
In most cases, transmission of the virus to others is unlikely after 7 to 10 days of illness. This applies in particular to people with a functioning immune system. However, exceptions confirm the rule. Therefore, caution is advised – even after booster vaccination has been given [1].
Undoubtedly, the Corona vaccines recommended by the Robert Koch and Paul Ehrlich Institutes have been shown to protect against severe COVID-19 events. If the body becomes less severely ill, there is thus also a chance of being affected by an infection for less time [4, 19].
Nevertheless, even a person with booster vaccination should always remember the currently valid guidelines for the resolution of quarantine hold. Finally, despite booster vaccination and resolved symptoms, infectiousness and thus a risk of infection may still persist.
The ability to "test out" of quarantine is therefore intended to pre-empt this problem. In this way, no one should remain in quarantine for an unnecessarily long time, but also no unnecessary risk of infection for other people should be accepted. The current rules can be found here.
How long does recovery take?
The duration of recovery from COVID-19 depends primarily on the severity of the disease, the age of the person affected and any previous illnesses. In the case of a mild course, recovery takes an average of 2 weeks. In contrast, severe courses are more likely to last 3 to 6 weeks. However, depending on the above factors, recovery time varies widely [30].
Particularly in individuals who have had to be hospitalized for COVID-19, health limitations may persist long after discharge.
However, even people with mild COVID-19 courses, as well as younger people, may continue to experience reduced performance or other symptoms for weeks (see below) [31].
Overall, physicians are increasingly observing courses of illness in which affected individuals initially feel as if they have recovered before symptoms reappear and recur [32].
Long Covid: long-term effects after corona infection
Since the COVID-19 disease – as the name suggests – has only existed since late 2019, research into its long-term effects is still ongoing and thus not yet complete. However, initial research shows that affected individuals – even after a mild COVID-19 course – may still have symptoms weeks and months after infection. Depending on the study, this still affects 10 to 60 percent of all infected persons [15, 30, 33-37].
Symptoms of long covid include [30, 32, 33]:
– Tiredness, exhaustion and fatigue – Headaches – Breathing difficulties and shortness of breath – Smell and taste disorders – Cognitive impairments ("brain fog") – Depressive moods – Sleep and anxiety disorders – Feeling of prere on the chest – Cough – Muscle, joint and limb pain – Fever – Diarrhea – Feeling of pins and needles – Heart palpitations and palpitations – Chest pain – Skin rashes
These symptoms occur individually in some people and in combination in others. There have also been reports of new onset metabolic diseases such as diabetes [33, 38].
In addition, there are a number of disease sequelae that can occur, especially in people with severe COVID-19 courses, and can then persist for longer periods of time. The latter include [30, 39-41]:
a reduced lung function – In particular, sufferers with severe pneumonia may have permanent limitations. Damage to the heart muscle – Imaging has revealed permanent changes in the myocardium of COVID-19 patients. Nerve damage due to ITS stay – Regardless of the disease pattern, neurologic sequelae can occur in people who have been in an intensive care unit (ITS) for an extended period of time. These are known as "critical illness-polyneuropathy" as well as "critical illness-myopathy" [529]. Permanent muscle weakness and even paralysis can be the result.
Good to know: Some of the transient as well as permanent long-term sequelae are not specific to SARS-CoV-2 coronavirus. Other viral diseases that can cause pneumonia, sometimes requiring treatment in an intensive care unit, can also have similar effects [15].
The extent to which some of these long-term sequelae in COVID-19 are permanent and thus irreversible cannot be said with certainty at this time and requires further research [15].
The role of vaccination in disease progression
In addition to vaccination, new viral variants can also significantly influence the course of COVID-19 disease.
Although the current COVID-19 vaccines are able to prevent both Neutralizing antibodies as well as the cellular immunity of the immune system to stimulate and thus react to various surface features of the coronavirus. Nevertheless, a high number of mutations – as seen in the Case of the omicron variant – reduce vaccine efficacy.
For the vaccine protection to take effect, it is essential to be fully vaccinated. This is the only way to best reduce the likelihood of immune escape (when viruses bypass the immune response) [42].
Why booster vaccination is important
Related to omicron (B.1.1.529), it has also emerged from study results that the protective effect of the vaccination diminishes significantly over time. Accordingly, from about 15 weeks after the second vaccine dose, it is no longer possible to speak of sufficient protection against symptomatic disease [42].
However, according to studies, a booster vaccination can effectively remedy this situation. The STIKO therefore recommends this booster vaccination already 3 months after administration of the second dose [42].
Corona symptoms despite vaccination (in the case of vaccine breakthrough)
With a full Corona vaccination and subsequent booster vaccination, people can significantly reduce their risk of becoming severely ill with COVID-19. This also reduces the risk of developing symptoms in the first place. However, vaccine protection is by no means 100% [4, 42].
According to the RKI, a vaccine breakthrough occurs when "a fully vaccinated person is found to have PCR-confirmed SARS-CoV-2 infection with symptomatology."If someone is PCR-positive but shows no symptoms (i.e., has an asymptomatic course), one would not speak of vaccine breakthrough [42].
The more people in a population are vaccinated, the higher the proportion of vaccinated people among those infected will inevitably be. This is then by no means evidence of a lack of vaccine efficacy, but merely a mathematical arithmetic game. Looking at the individual, a vaccinated person is then still significantly less likely to become infected than an unvaccinated person. However, because there are then many more vaccinated than unvaccinated individuals, it now affects more vaccinated individuals in the overall population [42].
What symptoms after vaccination?
The symptoms of a breakthrough infection can in principle correspond to the COVID-19 symptoms in an unvaccinated person. However, studies showed that symptoms tended to be milder in a vaccine breakthrough. Severe courses are much rarer [4].
Further studies suggest that breakthrough infection is associated with fewer symptoms, shorter duration of symptoms, and a higher likelihood of an asymptomatic course [4].
Vaccination despite symptoms?
The Robert Koch Institute (RKI) has clear guidelines for when a so-called contraindication for vaccination exists. In the first place are so-called "acute diseases requiring treatment". Mild or chronic symptoms do not count here, but should be discussed with the vaccinating physician [43].
The RKI explicitly emphasizes that "banal infections, even if they are accompanied by subfebrile temperatures (≤ 38.5 °C), do not constitute a contraindication to vaccination [43].
Adverse drug reactions in previous vaccinations and allergies to vaccine components can be a contraindication. Special patient groups such as pregnant women or people with immunodeficiency should clarify the vaccination indication with their physicians beforehand [43].
The contents of this article reflect the current state of scientific knowledge at the time of publication and have been written to the best of our knowledge. However, this article is not a substitute for medical advice and diagnosis. If you have any questions, consult your general practitioner.