For more than 18 months, we’ve been living in a COVID world. At the start of the pandemic, government agencies and health authorities scrambled to educate people on how to recognise virus symptoms.
However, as the virus has evolved, it appears that the most common symptoms have changed as well.
Emerging evidence suggests that people infected with the Delta variant — which is responsible for the majority of current cases in Australia and is widely spread around the world — are experiencing symptoms that differ from those commonly associated with COVID earlier in the pandemic.
Humans are dynamic beings. Our immune systems differ as a result of our differences. This means that the same virus can cause a variety of signs and symptoms. A visible sign, such as a rash, is referred to as a sign. A symptom is something that can be felt, such as a sore throat.
A virus’s ability to cause illness is determined by two key factors:
1.Viral factors include replication speed, mode of transmission, and so on. As a virus evolves, its viral factors change.
2. The host factors are unique to the individual. Age, gender, medications, diet, exercise, health, and stress are all factors that can influence host factors.
So when we talk about the signs and symptoms of a virus, we’re talking about the most common ones. To determine this, we must collect data from individual cases.
It’s important to note that this data isn’t always easy to collect or analyse in order to avoid bias. For example, older people may have different symptoms than younger people, and data collection from patients in a hospital may differ from data collection from patients in a GP clinic.
So, what are the most common symptoms of the Delta variant?
Data from the United Kingdom suggest that the most common COVID symptoms may have changed from those previously associated with the virus, based on a self-reporting system via a mobile app.
The reports make no mention of which COVID variant the participants are infected with. However, given that Delta is currently predominating in the UK, it’s a safe bet that the symptoms we’re seeing here are due to the Delta variant.
While fever and cough have always been common COVID symptoms, as have headache and sore throat for some people, a runny nose was rarely reported in previous data.
Meanwhile, loss of smell, which was once quite common, has dropped to ninth place.
There are several possible explanations for why the symptoms are evolving in this manner. It could be because the data was originally gathered primarily from hospitalised patients, who were therefore more likely to be sicker. And, because older age groups have higher rates of vaccination coverage, younger people now account for a larger proportion of COVID cases, and they tend to have milder symptoms.
It could also be due to the virus’s evolution and the unique characteristics (viral factors) of the Delta variant. However, it is unclear why symptoms may be changing.
While we still have a lot to learn about the Delta variant, this new information is significant because it shows that what we might think of as a mild winter cold — a runny nose and a sore throat — could actually be a case of COVID-19.
This data demonstrates the importance of public science. At the same time, we must keep in mind that the results have not yet been fully analysed or stratified. That is, “host factors” like age, gender, other illnesses, medications, and so on have not been taken into account, as they would in a rigorous clinical trial.
And, as with all self-reported data, we must acknowledge that there may be some flaws in the results.
Is there any effect of vaccination on the symptoms?
Despite the fact that new viral variants can reduce vaccine effectiveness, the Delta vaccines available in Australia (Pfizer and AstraZeneca) still appear to offer good protection against symptomatic COVID-19 after two doses.
Importantly, both vaccines have been shown to provide greater than 90% protection against severe disease requiring hospitalisation.
A recent “superspreader” event in New South Wales emphasised the significance of vaccination. According to reports, none of the 24 people who became infected with the Delta variant were vaccinated out of the 30 people who attended the birthday party. The six vaccinated partygoers did not contract COVID-19.
In some cases, infection may occur after vaccination, but the viral load will most likely be lower and the symptoms will be much milder than they would be without vaccination.
Evidence is mounting that Delta is more infectious than the original SARS-CoV-2 and other variants of the virus.
It is critical to recognise that the environment is also changing. People have become more accustomed to social distancing, seasons change, vaccination rates fluctuate — all of these factors influence the data.
However, scientists are becoming increasingly confident that the Delta variant represents a more transmissible SARS-CoV-2 strain.