Symptom progression & duration of corona

COVID-19 comes in many forms

Two people who become infected with the coronavirus often have very different courses. While one person has already recovered before they even realize their infection, another can become seriously ill. This difference has been further exacerbated by vaccinations and new virus variants. While all corona vaccines approved in Europe have been proven to protect against severe courses of the disease, unvaccinated adults can still be severely affected by new virus mutations.

The Omikron variant

Initially, people contracted the Alpha and Delta variants of the virus. Now the Omikron variant is dominant and characterized by a large number of mutations, which makes it easier for it to escape the antibodies acquired through vaccination or recovery. This has enabled it to displace other variants and lead to a (renewed) corona infection in many vaccinated and recovered people. As a result, numerous Omikron subtypes emerged, which had ever greater spreading advantages. Subtype followed subtype within a relatively short time - such as BA.2, BA.4 and BA.5. The current Omicron variant is called JN.1, with its subtype KP.3.1.1 predominant and responsible for most new infections - with an upward trend. Other Omikron subtypes or completely new virus variants are possible [1, 2]. 

The data on disease severity in the case of Omikron indicates milder courses on average. However, hospital admissions and stays in intensive care units can still occur, particularly in older age groups [44, 45].

The most common symptoms

In spring 2020, the disease was still a mystery. But we now know a lot more. Most people were already sick. One person was coughing, another was breathing heavily. And some got away without any symptoms at all.

Thanks to studies, the frequency of the various symptoms has been better analyzed and understood over time. On average, one in three of all infected people remain asymptomatic. After vaccination, this proportion can be even higher [3, 4].

The most common symptoms are (in descending order): cough, fever, aching limbs, headache, shortness of breath, sore throat, diarrhea, runny nose, loss of smell or taste, as well as nausea or vomiting.

Other symptoms may include loss of appetite, weight loss, abdominal pain, red eyes, skin rash, swelling of the lymph nodes, drowsiness and sleep problems, depressed mood, confusion, memory impairment and loss of consciousness [5, 8].

Observational studies suggest that the risk of severe disease is lower with Omikron than with previous variants. Symptoms can in principle be the same [1, 2]. Overall, the nasopharynx appears to be more commonly affected in Omicron, whereas previous variants tended to affect the bronchia and lungs [46].

Incubation period: from infection to the first symptoms

The incubation period describes the time between the moment of infection and 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 Omikron, symptoms appear on average around 3 days after contact with the virus. The total range is 0 to 8 days. However, in almost all corona-infected people with symptoms, these occur after 10 to 14 days at the latest [7, 9, 11].

SARS-CoV-2 virus transmission 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 so successful [12].

From mild to life-threatening

The course of the disease can be mild, severe or life-threatening. “Severe” means that the affected person has shortness of breath and a restricted oxygen supply due to extensive lung involvement. Life-threatening courses result in lung failure, circulatory failure (also known as shock) or simultaneous failure of several organs [14]. When scientists speak of “mild”, this nevertheless also includes unpleasant courses of the disease.

Time intervals from SARS-CoV-2 infection to hospitalization, intensive care unit and other

The mortality rate for confirmed SARS-CoV-2 infections is estimated at around 2 to 5 %. But since many infections remain undetected, the mortality rate is probably between 0.15% and 1% of all infected persons. In any case, the mortality figures that look at individual age groups are much more meaningful [20, 21].

In Germany, men and women are affected about equally often. However, on average, men contract COVID-19 more severely and die from the disease about twice as often as women [5, 16]

Severe course: What to expect?

Even in those infected with a severe course, the disease often begins gradually. The following symptoms can occur in severe cases of SARS-CoV-2 [15, 23, 24]:

Pneumonia - Pneumonia means that parts of the lungs can no longer be properly ventilated. This results in a restricted oxygen supply to the body.

Lung failure - Acute respiratory distress syndrome (ARDS) refers to severe impairment of lung function in response to damaging stimuli such as severe pneumonia. Those affected have a poor prognosis despite artificial respiration.

Formation of blood clots - An increased number of so-called thrombi can form in the blood. These small blood clots can block vessels and even be swept along with the blood flow - as so-called embolisms - into various parts of the body such as the legs, lungs and brain. The result is a lack of oxygen in the affected region.

Heart failure - In severe cases, cardiac arrhythmia, damage to the heart muscle and even circulatory failure can occur.

Kidney failure - This can occur as a complication in severely ill COVID patients. Patients sometimes have to be treated with dialysis.

Overshooting immune reactions - Some patients experience a persistent overshooting response of the immune system, which can be detected in the laboratory. This reaction is associated with a poor prognosis.

Other infections - In severe cases of COVID-19, the body is severely weakened and therefore more susceptible to other pathogens such as bacteria or fungi.

Neurological complications - The SARS-CoV-2 coronavirus also appears to affect the nervous system, causing various neurological disorders.

How deaths have developed since the start of the pandemic:

When does what end: symptoms, risk of infection, virus detection and recovery

People infected with the coronavirus can infect other people, regardless of whether they have symptoms or not. Infection is also possible even before symptoms appear [25].

At the same time, the risk of transmission appears to be highest around the onset of symptoms. In corona-infected people with a functioning immune system, the probability of transmission then decreases again as the disease progresses. In people with a severe course of the disease, however, the risk of infection for others is also increased in the longer term [26].

A corona infection is detected in the laboratory using a so-called “polymerase chain reaction” (PCR). The test result usually provides reliable information about whether a person is infected and therefore infectious to others [27, 28]. The genetic material of the virus can still be detected by PCR weeks after the illness without the virus still multiplying or the person being infectious.

The last coronavirus protection measures expired on April 7, 2023. This means that the last measures no longer apply - such as wearing an FFP2 mask when visiting a hospital or care home.[47]

As there are no longer any strict guidelines, people have to rely on their own risk management. And the virus remains unpredictable. The Covid variants are still evolving much faster than the influenza variants and so far occur all year round without favoring a particular season.

How long am I contagious with a booster vaccination?

The virus is unlikely to be transmitted to other people after 7 to 10 days of illness. However, exceptions prove the rule. Caution is therefore advised - even after a booster vaccination [1].

There is no doubt that the coronavirus vaccines recommended by the Robert Koch and Paul Ehrlich Institutes can provide proven protection against severe cases of COVID-19. If the body becomes less severely ill, there is therefore also a chance of being affected by an infection for less time [4, 19].

How long does recovery take?

The duration of recovery from COVID-19 depends primarily on how severe the course of the disease is, how old those affected are and what pre-existing conditions they have. Mild cases take an average of 2 weeks to recover. On the other hand, severe cases are more likely to take 3 to 6 weeks. However, the recovery time varies greatly depending on the factors mentioned above [30].

In particular, people who have been hospitalized for COVID-19 may continue to have health restrictions long after discharge. But even people with mild cases of COVID-19 and younger people can continue to experience reduced performance or other symptoms for weeks (see below) [31]. Overall, doctors are increasingly observing courses of the disease in which those affected initially feel as if they have recovered before symptoms reappear and recur [32].

Long Covid: long-term consequences after a corona infection

As the disease COVID-19 - as the name suggests - has only existed since the end of 2019, research into the long-term consequences has not yet been completed. However, initial research results show that those affected - even after a mild course of COVID-19 - can still have symptoms weeks and months after infection.

The Robert Koch Institute states: “The exact incidence of Long COVID can still not be reliably estimated. In particular, there is a lack of population-representative, controlled studies with sufficient follow-up time that allow a comparison of people with and without a past SARS-CoV-2 infection.” [48]

The symptoms of Long Covid include [30, 32, 33]:

• Tiredness, exhaustion and fatigue
• Headaches
• Breathing difficulties and shortness of breath
• Odor and taste disorders
• Cognitive impairment (“brain fog”)
• Depressive moods
• Sleep and anxiety disorders
• Feeling of pressure on the chest
• Cough
• Muscle, joint and limb pain
• Fever
• Diarrhea
• Feeling of pins and needles
• Palpitations and palpitations
• Chest pain
• Skin rashes

These symptoms can occur individually or in combination. There have also been reports of new metabolic disorders such as diabetes [33, 38].

There are also a number of consequences of the disease that occur primarily in people with severe cases of COVID-19 and can persist for longer.

These include [30, 39-41]:

• Impaired lung function - permanent restrictions can occur, particularly in patients with severe pneumonia.
• Damage to the heart muscle - permanent changes to the heart muscle in COVID-19 patients have been detected using imaging.
• Nerve damage due to ICU stay - Regardless of the clinical picture, people who have been in an intensive care unit (ICU) for a long time can suffer neurological damage. This is known as “critical illness polyneuropathy” and “critical illness myopathy”. This can result in permanent muscle weakness or even paralysis.

Good to know: Some of the temporary and permanent long-term effects are not specific to the SARS-CoV-2 coronavirus. Other viral diseases that can cause pneumonia and sometimes require treatment in an intensive care unit can also have similar effects [15].

The extent to which some of these long-term consequences of COVID-19 are permanent and therefore irreversible cannot be said with certainty at this time and requires further research [15].

The role of vaccinations in the course of the disease

In addition to vaccinations, new virus variants can also significantly influence the course of COVID-19. The current COVID-19 vaccines are able to stimulate both neutralizing antibodies and the cellular immunity of the immune system and thus react to various surface characteristics of the coronavirus. Nevertheless, a high number of mutations can reduce the effectiveness of the vaccine.

In order for the vaccine to be effective, it is still advisable for several population groups to be vaccinated. This is the best way to reduce the likelihood of immune escape (when the viruses evade the immune response).

This includes, among others:

- People aged 60 and over,

- Residents in care facilities,

- Medical and nursing staff with direct contact with patients or residents of retirement and nursing homes. [49]

Vaccination and Omikron

Studies have shown the following effects on immunity: If an unvaccinated person becomes infected with Omikron, they subsequently have almost exclusive immunity to further Omikron infections. A second infection with Omikron is then still possible, but is usually accompanied by significantly milder symptoms [46].

If, on the other hand, a fully vaccinated person becomes infected with Omikron (so-called vaccine breakthrough), the immediate course of the disease is not only milder on average. The person also has the advantage that the immunization effect from “vaccination plus Omikron infection” is significantly broader - i.e. can potentially also protect against other coronavirus variants [46].

Why booster vaccination can be important

Due to the high number of mutations, the Omikron subtypes are sometimes able to circumvent a built-up immunity. This is also referred to as “immune evasion” or “immune escape” [46].

It is not without reason that the emergence of the Omikron variant has led to a large number of re-infections or infections despite previous vaccination. People with a booster vaccination have higher overall Omicron vaccination protection. They are therefore generally less likely to develop symptoms in the event of an Omikron infection. However, the role of booster vaccination is much more important with regard to severe courses of disease, for which vaccination is still worthwhile [46].

Corona symptoms despite vaccination

With a full coronavirus vaccination and subsequent booster vaccination, people can significantly reduce their risk of becoming seriously ill with COVID-19. The risk of developing symptoms at all is also lower. But vaccination protection is by no means 100% [4].

According to the RKI, a vaccination breakthrough occurs when “a PCR-confirmed SARS-CoV-2 infection with symptoms is detected in a fully vaccinated person.” If someone is PCR-positive but shows no symptoms (i.e. has an asymptomatic course), one would not speak of a vaccination breakthrough].

The more people in a population are vaccinated, the higher the proportion of vaccinated people among those infected will inevitably be. This is by no means proof of a lack of vaccination effectiveness, but merely a mathematical calculation. Looking at the individual, it is still much less likely for a vaccinated person to become infected than an unvaccinated person. However, since there are then many more vaccinated people than unvaccinated people, this also affects more vaccinated people in the overall population [42].

What symptoms after vaccination?

In principle, the symptoms of a breakthrough infection can correspond to the COVID-19 symptoms in an unvaccinated person. However, the symptoms of a vaccine breakthrough tend to be milder. Severe cases are much rarer. Studies suggest that a breakthrough infection is associated with a lower number of symptoms, a shorter duration of symptoms and a higher probability of an asymptomatic course [4].

Vaccinating despite symptoms?

The Robert Koch Institute (RKI) has clear guidelines on when a so-called contraindication to vaccination exists. First and foremost are so-called “acute illnesses requiring treatment”. Mild or chronic symptoms are usually not included, but should still be discussed with the vaccinating doctors [43].

The RKI explicitly emphasizes that “banal infections, even if they are accompanied by subfebrile temperatures (≤ 38.5 °C), are not a contraindication to vaccination.

However, adverse drug reactions during previous vaccinations and allergies to vaccine components may be a contraindication. Special patient groups such as pregnant women or people with immunodeficiency should always clarify the indication for vaccination with their doctor beforehand [43].

During the coronavirus pandemic, data played a crucial role in medical research. It made it possible to quickly understand the virus, analyze the course of the infection and develop effective measures. The data made it possible to monitor the spread of the virus in real time and develop vaccines in record time. Clinical studies and the analysis of patient data helped to evaluate treatments and investigate long-term consequences. Without rapid global data sharing, the fight against COVID-19 would have been much slower and less effective.

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