COVID-19 variants have gone through unique changes that make them different from the original strain of the virus (the strain that came before the “alpha” variant). These changes can cause some variants to spread more easily or cause different symptoms.

All variants cause similar COVID-19 symptoms, including cough, fever, and fatigue. However, some variants have symptom presentations that are unique from one another. In addition, symptoms can vary by person, region, and vaccination status.

There are a number of variants that have been detected and are being tracked and studied globally. Those variants span the four World Health Organization categories used to classify variants, ranging from least concerning to most concerning:

1) Variant Being Monitored (VBM) - Alpha (B.1.1.7 and Q lineages)] - Beta (B.1.351 and descendent lineages) - Gamma (P.1 and descendent lineages) - Epsilon (B.1.427 and B.1.429) - Eta (B.1.525) - Iota (B.1.526) - Kappa (B.1.617.1) - 1.617.3 - Mu (B.1.621, B.1.621.1) - Zeta (P.2)

2) Variant of Interest (VOI)

3)Variant of Concern (VOC) - Delta (B.1.617.2 and AY lineages) - Omicron (B.1.1.529 and BA lineages)

4)Variant of High Consequence (VOHC)

Given that the Alpha, Delta, and Omicron variants have been the most closely followed as well as the most concerning and widespread, we focus in this explainer on those three variants and their lineages (a group of closely related viruses with a common ancestor that can be thought of as families). 

Becker's Hospital Review compiled a list of frequently reported symptoms for certain COVID variants based on emerging research in February 2022.

For the Alpha variant, the following symptoms were reported most frequently:

• New loss of taste or smell
• Fever or chills
• Cough
• Shortness of breath or difficulty breathing
• Fatigue
• Muscle or body aches
• Headache
• Sore throat
• Congestion or runny nose
• Nausea or vomiting
• Diarrhea

For the Delta variant, the following symptoms were reported most frequently:

• Sore throat
• Headache
• Runny nose
• Fever
• Diarrhea/GI problems

For the Omicron BA.1 variant, the following symptoms were reported most frequently:

• Sore throat
• Headache
• Runny nose
• Congestion
• Cough
• Lower back pain 
• Fatigue

It should be noted that unvaccinated people appeared to present similar (minor) symptoms as vaccinated people, but that there are subtle differences, with vaccinated people more likely to have more minor symptoms such as headache, congestion, and sinus pain compared to slightly less minor symptoms such as shortness of breath and fever. In addition, the major complaints in patients with severe omicron cases – who are mostly unvaccinated – have been fever and respiratory symptoms that require oxygen.

As clear from the list above, there is significant overlap in symptoms across these variants. Headache and sore throat, for instance, are commonly reported symptoms across all three. 

However, there are also notable differences. For instance, unlike the Alpha and Delta variants, the Omicron variant does not appear to present with gastrointestinal distress symptoms.the Alpha and Delta variants. The Alpha variant also presents with more frequently reported symptoms than the other variants, including muscle aches and shortness of breath, which are not frequently reported with Delta and Omicron.

A number of other studies and projects have confirmed differences in symptoms across variants. For instance, another research project called the ZOE COVID symptom study brought together academics and medical experts with ZOE – a health science company - to develop a not-for-profit app that helps researchers better identify and understand symptoms of COVID-19 and more about the virus. 

The app has collected self-reported data from users in the United States, United Kingdom, and Sweden about their illness and symptoms. Research from the app has shown that some variants present differently than others while most share some major symptoms.

For example, shortness of breath has been a rare self-reported occurrence in people infected with the Omicron variant but occurs 'sometimes' in people infected with the Delta and variants that occurred before the Delta variant (pre-Delta variants). As another example, sneezing is reported as a common symptom with Omicron but only occurs sometimes with the Delta variant and rarely with the Pre-Delta variants.

Symptom duration can also differ. For instance, the same study showed that participant symptoms lasted on average 6.9 days when Omicron dominated, compared with 8.9 days when Delta dominated. 

Research is ongoing to understand exactly why each variant and subvariant is resulting in different symptoms. What we do know, however, is that any time a virus mutates, it can cause different or new symptoms. This is partially because the variant is operating a bit differently than other variants, and, relatedly could also have to do with giving the virus an advantage; for instance, if a variant presents with less severe symptoms, people will be less likely to die and it will be more likely to spread. 

The severity and variety of symptoms, however, are not necessarily related to the level of infectiousness (virality). 

For instance, research has shown that though the Omicron variant and subvariants appear to be more transmissible than the Delta and Alpha variants, they also appear to be less severe than previous variants and present similarly to a head cold compared to earlier versions of the virus. Omicron symptoms are similar to other COVID-19 variants, particularly those that impact the upper respiratory system outside a loss of taste and smell which are not frequently reported with this variant. 

Additionally, long COVID symptoms might be different based on which variant (or variants) a person was infected with. 

For instance, patients infected with the original COVID-19 virus who developed long COVID experienced the following symptoms at higher rates than the Alpha variant:  - Fatigue - Insomnia - Dysgeusia (altered taste) - Impaired hearing

and the following symptoms at LOWER rates than the Alpha variant:  - Dyspnea (difficult breathing) - Brain fog - Myalgia (muscle pain) - Anxiety/depression

More research is ongoing to understand the differences in symptoms from COVID-19 across current and potential future variants, as well as why symptoms differ. 

ince the pandemic began, scientists have been studying COVID-19 variants to learn about how their structures may cause changes in symptoms, the way the virus spreads, their level of infectiousness, how they respond to vaccines, and more. 

Understanding COVID-19 symptoms by variant is helpful for a range of reasons. Some of these reasons include detecting the virus, especially by individuals at home, preparing patients for symptom management, and planning for measures and interventions needed to help alleviate symptoms – from at-home pulse oximeters to adjusting hospital capacity. 

As we learn more about each variant, we can understand what symptoms each may cause and why that may occur.