Got COVID? Your symptoms may depend on your vaccination status

The coronavirus that causes COVID-19 is really starting to fit in.

Now that it’s establishing itself among humans for a long stay, researchers are finding that the symptoms it causes are increasingly resembling those of the flu, colds, and even allergies.

This trend is particularly pronounced among those who have been vaccinated. But even when the unvaccinated are infected, they often report an array of generalized symptoms that could pass for one of several other common infections, all of which are currently on the rise in the United States.

The latest update comes from the Zoe Health Study, a COVID-19 symptom tracker developed by researchers at Harvard, Stanford and King’s College in London. The results reflect symptoms reported by users of the Zoe-COVID study over the past few weeks App in the UK as new COVID cases tick ominously higher.

For example: sneezing is now a very common symptom of COVID-19, reported with increasing frequency by vaccinated individuals.

This appears to be part of a shift in COVID-19 symptoms initiated by the Omicron variant, said Dr. John O’Horo, an infectious disease physician at the Mayo Clinic in Rochester, Minnesota. Omicron infections cause more upper respiratory tract symptoms than infections caused by previous variants, which were more likely to lead to pneumonia and other lower respiratory tract diseases.

Nowadays, O’Horo said, “I don’t think it’s really possible to use patients’ initial symptoms to distinguish COVID from what we’ve long termed ‘flu-like illnesses.’ His tool will distinguish between flu and COVID-19, he added.

Continued testing will also help the CDC track the progress of COVID-19 and pave the way for coronavirus-infected patients who are at risk of becoming seriously ill to be steered toward antivirals and other treatments.

Since the beginning of the pandemic, fever, cough and shortness of breath have been considered typical symptoms of COVID-19. A few months into the pandemic, the Centers for Disease Control and Prevention added chills, muscle aches, a headache and a sore throat.

In a short time, patient apps and websites alerted the CDC to loss of taste and smell, along with less common symptoms such as “COVID fingers” and “COVID toes” — two examples of rashes that are sometimes a patient’s only sign of illness.

Zoe Health’s new update on common COVID-19 symptoms has observed the most notable changes in reports from people who had received at least two doses of the vaccine before becoming infected. For this group, shortness of breath, which had long been in the top 5, was downgraded to the 28th most cited symptom. Loss of smell is now #6 – still fairly common. And fever is now #8.

The new ranking of symptoms for people who have received at least two doses of vaccine is:

1. Sore throat
2. Runny nose
3. Stuffy nose
4. Persistent cough
5. Headache

Reports of sneezing as a COVID symptom have surfaced from people who have received at least one dose of the vaccine. But sneezing has not been commonly reported by those who have remained unvaccinated.

Nevertheless, the range of symptoms reported by the unvaccinated did not differ radically from those reported by those who were fully vaccinated but not boosted. For the most part, they just appeared in a different order:

1. Headache
2. Sore throat
3. Runny nose
4. Fever
5. Persistent cough

And for those who only had a single vaccine, sneezing was on the list instead of a fever or a stuffy nose:

1. Headache
2. Runny nose
3. Sore throat
4. Sneezing
5. Persistent cough

In the United States, online apps that track COVID-19 symptoms over time have never gained much traction due to political suspicions and privacy concerns, said Enbal Shacham, professor of behavioral health and science in the Saint’s College of Public Health and Social Justice Louis University.

Shachem and her colleagues have developed such an app, and Google and Apple have each launched one. However, their use was limited by the fact that collecting data on symptoms was incidental to the apps’ primary design – to aid in contact tracing.

That has robbed researchers and public health officials of important insights into how coronavirus infection unfolds and how that condition has changed over time, Shacham said. Physicians have a clear understanding of the clinical pathways that critically ill patients follow because they are under surveillance in hospitals, but the mild and moderate illnesses that account for the majority of COVID-19 cases are less well understood.

“We could have a lot more insight into the timing of people’s symptoms, how they changed over time, how people’s experiences differed,” she said. “We really could know so much more, in real time, than we do.”