It has been over a year since Covid-19 landed in the United States. And the variety of previously disconcerting symptoms, such as cough, fever, shortness of breath and loss of taste and smell, are now very familiar to doctors across the country.
The range of possibilities when someone appears in a doctor’s office with new respiratory symptoms “is very, very limited these days,” said Anish Mehta, medical director of clinical quality and virtual health at Eden Health, and assistant clinical professor of medicine at the Icahn School of Medicine on Mount Sinai. “It will probably be Covid if you have a fever and cough or if you have a fever and feel pain in your muscles.”
Medical researchers also learned more about how a Covid-19 infection can spread to the circulatory, nervous and immune systems with symptoms such as skin rashes, blood clots, strokes and even foot injuries called “covered toes”. They are also more familiar with the more than 10 percent of Covid survivors who report long-term symptoms, including poor reasoning and concentration, heart palpitations, hair loss and mood swings.
However, even now, researchers are finding new symptoms. Tim Spector, professor of molecular epidemiology at King’s College London, has been studying Covid-19 during the pandemic through a Covid-19 Symptom Study smartphone app. He recently started receiving reports of mouth ulcers and what he calls Covid’s tongue – a diffuse yellowish-white coating on the tongue.
“It happened because people sent me pictures of their languages,” said Spector. “I posted them and then people started … realizing it was what they originally had when they had Covid. It is a strange phenomenon that no doctor thought was related. “
Although cases and hospitalizations are declining and several Covid-19 vaccines are being launched, the SARS-CoV-2 virus, which causes Covid-19, is still spreading and new variants are threatening to undo some of the progress made during the pandemic. The more the virus spreads, the more likely it is to acquire new mutations. Changes in symptoms can be a warning sign of these changes in the virus. Therefore, doctors have to remain alert.
“I think the lesson is that unusual symptoms can come out of nowhere without a clear explanation,” said Andrew Chan, professor of immunology and infectious diseases at the Harvard School of Public Health TH Chan, who collaborated with Spector on the symptom study app. “It has to be on the mind of every health professional.”
The list of symptoms for Covid-19 is still getting longer
The fact that Covid-19 has spread so widely, with 115 million cases worldwide so far, means that the disease has had opportunities to affect people in a variety of circumstances, including pre-existing health conditions, age, nutrition, standards of living and access to health care. The way Covid-19 interacts with these variables explains why there are so many different symptoms.
According to the Centers for Disease Control and Prevention, the most common Covid-19 signs are:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Fatigue
- New loss of taste or smell
- Headache
- Muscle or body aches
- Diarrhea
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
- Diarrhea
It is useful to think about Covid-19’s progression in stages. During the initial stage of the disease, it is the virus itself that causes most of the damage, leading to many of the respiratory symptoms, such as loss of taste or smell, which remains one of the most predictive symptoms. As the disease progresses, the immune system’s response becomes the dominant factor, leading to effects such as fever, chills and inflammation. Once the virus disappears, damage from the virus and the immune response can last.
For example, Covid-19 can cause abnormal blood clotting. These clots can clog blood vessels, impairing the functioning of other organs, such as the liver or kidneys. Some of these effects can take weeks to manifest.
Another factor to be considered is that Covid-19 symptoms can be grouped into groups, which can signal the prognosis for the disease. On pre-printed paper using data from the Covid-19 symptom tracking application, the researchers identified six distinct symptom groups for Covid-19. For example, patients who experienced respiratory symptoms such as a sore throat and cough alongside gastrointestinal symptoms such as diarrhea and abdominal pain were much more likely to end up hospitalized than Covid-19 patients who had no gastrointestinal problems.
Clusters are also emerging as a long-term Covid warning sign. “We saw that people who experience fatigue, headache, shortness of breath, loss of smell – that type of symptom group in particular seems to be associated with an increased likelihood of developing long Covid,” said Chan.
Scientists are still trying to find out if Covid Long is due to the virus itself, other opportunistic infections or underlying underlying conditions exacerbated by the disease. “The underlying biology of why these things were activated by a virus is unclear,” said Chan. However, health officials are now concerned that these long-standing symptoms could be a huge indirect health crisis.
“I fear that some people who have had these effects and are three or four months away may not be on track to improve in a few more months,” Francis Collins, director of the National Institutes of Health, told NBC News on March 1. “When you consider that we know that 28 million people in the United States have had Covid, even though 1 percent of them have chronic, long-term consequences, that means a lot of people.”
However, at the same time, there are still people who are infected and have no symptoms, but can still spread the virus. Estimates vary, but researchers suspect that between 20 and 50 percent of SARS-CoV-2 infections do not produce symptoms and lead to illness.
So while researchers have a better understanding of the disease now, there is still a lot to learn. And as the disease continues to spread and transform, researchers fear that it may start to present itself in unexpected ways.
So far, people infected with the new variants have Covid-19 symptoms similar to the older variants
It is rare, but researchers have documented several cases of people being reinfected with SARS-CoV-2. For the most part, the second round of infection results in milder symptoms than the first. But several people became more seriously ill the second time and some died.
New variants of the virus that are spreading rapidly may increase the chances of this happening. Some of the variants have already been shown to be more transmissible and probably more deadly. In laboratory studies, antibodies produced to fight previous versions of the SARS-CoV-2 virus were less effective against some variants, such as variant B.1.351 found for the first time in South Africa.
This means that someone who ignored a previous fight with Covid-19 can later experience a more dangerous course of the disease. Some variants can also make Covid-19 vaccines less effective in preventing disease.
As for the way the variants look, they now appear in ways similar to previous versions of the virus. “As far as we can tell from the work we did through Covid’s symptom study, we didn’t see any tremendous differences in terms of the symptoms that people experience,” said Chan.
A UK survey found that variant B.1.1.7 led to some subtle changes in symptoms. “People with a test compatible with the new UK variant were more likely to report any symptoms and classic symptoms, but were less likely to report loss of taste and smell,” according to the UK’s Office of National Statistics.
But the United States is not conducting enough genetic surveillance to promptly identify new mutations in the virus as they arise. A sudden change in symptoms can end up being a warning sign that another new variant has arrived. And even more symptoms that doctors did not previously appreciate can arise.
“It just says that we need to be humble and realize that we know very little about this virus and keep an open mind,” said Spector.
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