Three weeks ago, I woke up completely drained of energy and with a great hacking cough that seemed to have materialised from nowhere. A quick Covid test informed me that I’d tested positive for the fourth time since the pandemic began back in 2020. But, other than seeing the same red lines on the plastic test, nothing about my recent brush with the illness felt familiar.

In fact, every time I’ve caught Covid over the last four years, my symptoms have been completely different. Catching the alpha variant at the end of 2020 caused me to lose my sense of taste and smell for three months. Second time around, I was completely asymptomatic, and the third saw me in bed for two weeks with classic flu symptoms. 

I’m not the only one who’s experienced these drastic differences in Covid symptoms. A study published in Nature Communications, which included data on more than 1.5 million randomly sampled adults in England, found that symptom profiles among those testing positive have changed with different varieties of Covid-19.

A report from the British Medical Journal backs this up, saying: “In the short space of a few years we’ve seen surprising changes in the way Covid-19 presents.” It found that at the start of the pandemic, the first commonly recorded symptoms were loss of smell and taste, followed by shortness of breath and a cough, followed by vascular injuries. However, since then there’s been an “evolution of symptom clusters and manifestations across the variants” with the “loss of sense of smell and taste nowhere near as prevalent as it used to be”.

So what’s behind these dramatically changing Covid symptoms? 

Well, research is still in its infancy when it comes to tracking Covid’s effects on the body. However, there are some theories as to why symptoms can appear so dramatically different each time we catch the virus. 

‘Immune memory’ 

“Individual variations in immune response, influenced by age, genetics and underlying health conditions, play a significant role in varying Covid symptoms,” Dr Simon Theobalds, a GP at Pall Mall Medical, tells Stylist. 

Generally, the more immunity people build up to a virus from vaccinations or infections, the milder their symptoms of subsequent infections tend to be. However, as Dr Ziyad Al-Aly, the chief of research and education services at the VA St. Louis Health Care System, tells the New York Times: “Anything from developing new medical conditions or ageing can affect how sick you get.” He even notes that small variations in our microbiome health can alter how we respond to an infection at one time or another.

We all have our own individual ‘immune memory’, explains Dr Theobalds. This is created from previous infections or vaccinations and it will affect how symptoms manifest themselves when we catch Covid.

Multiple organs

Covid is a complex virus that can affect huge areas of our body, which is another reason medics and scientists believe symptoms can vary so widely. 

“The virus has the ability to infect multiple organs, such as the lungs, heart and nervous system,” says Dr Theobalds. “This leads to diverse clinical presentations.”

Rapidly changing variants 

We all got used to remembering the name of the latest Covid variant to emerge as they were reported in the news, and it’s the virus’s ability to mutate so rapidly that’s deemed as one of the major reasons we experience such a wide variety of symptoms. Four years on from the beginning of the pandemic, the virus is still mutating. According to the WHO website, as of 28 June there are currently seven variants of interest circulating around the world.

“Different viral variants contribute to symptom variability,” says Dr Theobalds. “Each variant has unique mutations affecting its behaviour and interaction with the immune system. These mutations can alter symptoms by changing how the virus infects cells and triggers immune responses. Variants with higher transmissibility or virulence can evade immunity from past infections or vaccines.”

Exposure

Someone’s exposure to Covid – something scientists call ‘viral load’ – can also affect the kinds of symptoms you experience.

“Direct exposure to Covid is particularly dangerous threat to patients with certain underlying health conditions, like cardiovascular or autoimmune disease,” says Dr Theobolds.  

Essentially, Covid-19 is an incredibly complex virus, so it’s no wonder the symptoms we experience seem so bewildering. So, what can we do to safeguard ourselves and will it ever get easier to predict how a Covid infection will affect us?

When it comes to protecting yourself from Covid, Dr Teobalds says that all of the same precautions we took in lockdown still apply now. “Stay updated with vaccinations and boosters, practice good hand hygiene, wear masks in crowded areas with poor ventilation (especially if there’s a known outbreak), maintain physical distancing where possible and avoid close contact with people who are presenting symptoms or are known to be infected.”

However, there is hope we can get a better idea of how Covid might affect us in the future. “There are continual advances in genomic sequencing enabling tracking of mutations in SARS-CoV-2 variants and revealing how changes affect symptom profiles,” says Dr Theobalds. “Large-scale epidemiological data is helping identify symptom patterns linked to specific variants and ongoing clinical studies are enhancing our comprehension of variant effects across diverse populations.” 

But as we wait for our understanding of Covid to deepen, the WHO website currently lists the most common Covid symptoms as fever, chills and a sore throat. So if you’re experiencing any of these, it’s best to take a test. 

Image: Getty