The Symptoms of the Delta Variant Differ From Traditional COVID-19 – Here’s What To Look Out For

By Lara Herrero, Research Leader in Virology and Infectious Diseases, Griffith University, August 1, 2021

We have been living in a COVID world for over 18 months. At the start of the pandemic, government agencies and health authorities rushed to educate people about identifying symptoms of the virus.

But as the virus has evolved, its most common symptoms seem to have changed as well.

Emerging data suggests that people infected with the Delta variant — the variant behind most of the current cases in Australia and common around the world — are experiencing symptoms that differ from those we often experienced with COVID earlier in the pandemic. associated.

We are all different

People are dynamic. With our differences come different immune systems. This means that the same virus can cause different signs and symptoms in different ways.

A sign is something that is seen, such as a rash. A symptom is something that is felt, such as a sore throat.

The way a virus causes disease depends on two main factors:

viral factors include things like replication speed, transfer modes, and so on. Viral factors change as the virus evolves.
host factors are specific to the individual. Age, gender, medications, diet, exercise, health, and stress can all influence host factors.

So when we talk about the signs and symptoms of a virus, we’re talking about what’s most common. To determine this, we need to collect information from individual cases.

It is important to note that this data is not always easy to collect or analyze to ensure there is no bias. For example, older people may have different symptoms than younger people and the collection of data from patients in a hospital may be different from patients in a general practice.

So what are the common signs and symptoms of the Delta variant?

Using a self-reporting system via a mobile app, data from the UK suggests that the most common COVID symptoms may have changed from those we traditionally associated with the virus.

The reports do not take into account which COVID variant participants are infected with. But since Delta is currently predominant in the UK, it’s a safe bet that the symptoms we see here reflect the Delta variant.

Credit: The Conversation, CC BY-ND

While fever and cough have always been common COVID symptoms and headaches and sore throats are traditionally seen in some people, a runny nose was rarely reported in previous data. Meanwhile, loss of smell, which was originally quite common, now ranks ninth.

There are a few reasons why we may see the symptoms evolve in this way. It could be that the data originally came mainly from patients who entered the hospital and would therefore likely be sicker. And given higher vaccination rates in older age groups, younger people are now responsible for a higher proportion of COVID cases and tend to experience milder symptoms.

It can also be due to the evolution of the virus, and the different characteristics (viral factors) of the Delta variant. But why exactly the symptoms might change remains uncertain.

While we have yet to learn more about the Delta variant, this emerging data is important because it shows us that what we might see as just a mild winter cold — a runny nose and a sore throat — could be a case of COVID-19. .

This data highlights the power of public science. At the same time, we must bear in mind that the results have not yet been fully analyzed or stratified. That is, ‘host factors’ such as age, gender, other diseases, medications, and so on have not been taken into account, as in a rigorous clinical trial.

And as is the case with all self-reported data, we must recognize that there may be some errors in the results.

Does vaccination affect the symptoms?

Although new viral variants may compromise the effectiveness of vaccines, for Delta the vaccines available in Australia (Pfizer and AstraZeneca) still seem to provide good protection against symptomatic COVID-19 after two doses.

Importantly, both vaccines provide over 90% protection against serious illnesses requiring hospital treatment.

A recent ‘super spreader’ event in New South Wales highlighted the importance of vaccination. Of the 30 people who attended this birthday party, reports showed that none of the 24 people infected with the Delta variant had been vaccinated. The six vaccinated people at the party did not contract COVID-19.

In some cases infection is still possible after vaccination, but it is very likely that the viral load will be lower and the symptoms much milder than without vaccination.

We all have a role to play

There is some evidence that Delta is more contagious compared to the original SARS-CoV-2 and other variants of the virus.

It is important to understand that the environment also changes. People have become more complacent with social distancing, seasons change, vaccination rates vary — all of these factors affect the data.

But scientists are increasingly confident that the Delta variant represents a more transmissible SARS-CoV-2 strain.

As we face another COVID battle in Australia, we are being reminded that the war on COVID is not over and we all have a part to play. Get tested if you have symptoms, even if it’s “just a pinch.” Get vaccinated as soon as possible and follow the health advice.

Written by Lara Herrero, research leader in virology and infectious diseases, Griffith University.

Originally published on The Conversation.