As the virus has evolved, so have the symptoms, writes Professor Tim Spector.
For nearly two years, millions of members of the public have been submitting daily health reports to the ZOE COVID Study, helping us track the pandemic as it unfolds.
Notably, the 480 million reports submitted through the study’s app showed that as the virus has evolved, so have its symptoms.
Back in 2020, it quickly became apparent that the original and alpha versions of the coronavirus were caused by three very common symptoms – cough, fever and loss of smell – as well as at least 20 others. These included fatigue, headache, shortness of breath, muscle pain and gastrointestinal problems, as well as unusual phenomena such as skin rashes and ‘Covid tongue’.
When the delta appeared, we saw a change in the most commonly reported symptoms.
The first general symptoms such as shortness of breath, fever and loss of smell fell down the ranking. Cold-like symptoms — including runny nose, sore throat and persistent sneezing — became more common along with headache and cough, especially in people who had been vaccinated.
It appears that Omicron is continuing the trend set by Delta. It is causing symptoms that are like a regular cold, especially in people who have been vaccinated, and less common systemic symptoms, such as nausea, muscle pain, diarrhea and skin rash.
We looked at health reports from people who reported having COVID in December as Omicron spread to the UK, and compared them with data from early October, when Delta was the dominant version.
We then checked our findings from this comparison by analyzing data from a small group of contributors who were told by the government that their positive PCR results were suspicious or confirmed omicron infection.
Our analysis showed no significant difference in the overall symptom profile of Delta and Omicron, with runny nose, headache, fatigue, sneezing and sore throat among the top five symptoms in both time periods. But when it comes to the overall prevalence of symptoms, there are some clear differences.
Prevalence of Omicron symptoms according to the ZOE COVID app. (image: supplied)
For example, anosmia (loss of smell or taste) was in the top 10 in October, but has dropped to number 17. What was once a leading indicator of COVID, is now seen only in about one in five people who test positive. And according to our data, less than a third of people (29%) will ever experience a fever, which is much less common than previously thought.
Importantly, we found that only half of the people with COVID had any of the classic three symptoms of fever, cough or loss of smell.
How bad is Omicron?
This new variant is much more contagious than the previous variant, leading to an increase in cases across the UK and other countries. And although it’s not yet clear whether we’re facing a massive wave of hospitalizations from the disease, it’s important to remember that Omicron and Delta can feel like a cold to many of us, then. Also it can kill or cause long-term symptoms. Disrupts daily life, especially for those who have not been vaccinated or who have not been vaccinated.
So far, we have seen most of the cases in younger people, but now we are seeing cases increasing even in old age, while the overall infection rate is so high.
The recent increase in positive cases over the age of 75 is worrying, but we expect that high levels of vaccination in older and more vulnerable groups will continue to result in mild symptoms and few hospitalizations. The major problem with Omicron is the greater wave of illness absences among key healthcare workers.
Is it Omicron or winter?
The ZOE COVID Study App data tells us that the symptoms caused by the current COVID variants are similar to those of the common cold. This means that it is not possible to be sure what you have got based only on symptoms.
When COVID rates are high, a new sore throat, runny nose or unusual tiredness should be considered COVID until you are tested.
Because contributors to the ZOE COVID Study App log any daily symptoms, as well as the results of any COVID tests, we are able to track the spread of non-Covid colds as well. Just three months ago, nearly one in 12 people had new respiratory symptoms [in the UK] Tested positive for COVID. However, with Omicron currently about 50% of the ‘new winters’ are, in fact, COVID.
So if you or a family member is feeling unwell, there is a good chance it could be COVID, especially if you are sniffling and sneezing a lot.
You should stay at home and get tested to be sure.
In the end, regardless of government guidelines, whether you have COVID or not, it’s best to stay home if you’re feeling unwell or sick with cold-like symptoms, and to avoid contacts and if you go out. So wear a mask. Avoid spreading your germs to others who may be more vulnerable.
Originally published in The Conversation. Read the original article.
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