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  • With the increase in availability of vaccines and the rise of the Omicron variant, most vaccinated people and those who have received booster shots who develop COVID-19 will likely experience mild symptoms such as a sore throat, headache, and congestion.
  • Earlier variants, like Delta, frequently caused a loss of taste and smell, sore throat, and coughing.
  • Cases during the Omicron wave have been linked to more upper respiratory symptoms, such as runny nose, headache, fatigue, sneezing, and sore throat.

When doctors talk about mild COVID-19, they refer to an illness that is symptomatic but does not require hospitalization.

But the illnesses encompassed in the “mild” category can mean many symptoms, including headache, congestion, or a loss of taste and smell. Some people may even be bedridden with a fever for a week or longer.

While earlier variants, like Delta, frequently caused a loss of taste and smell, sore throat, and coughing, cases during the Omicron wave have been linked to more upper respiratory symptoms, such as runny nose, headache, fatigue, sneezing, and sore throat.

Scientists are still uncovering why symptoms vary from person to person.

Many believe the severity of infection depends on multiple contributing factors, including whether the person has been vaccinated and received a booster shot, the variant they were exposed to, how much virus they inhaled, their overall health, and how their immune system responded to the virus.

Tess Hooper, 31, of Los Angeles, tested positive for COVID-19 on Nov. 29, 2021.

She had spent Thanksgiving weekend with nine friends — all of whom, including Hooper, were fully vaccinated. One had received a booster shot.

One woman began to feel mildly ill a few days before the holiday weekend. She took two rapid tests, both of which came back negative, and the group figured the friend didn’t have COVID-19 — it was OK for her to come along.

But a couple of days into the vacation, two others began to feel sick, and by the end of the weekend, seven of the nine women tested positive.

Hooper lost only her taste and smell for 2 days before recovering. Otherwise, she felt fine and continued to work from home.

Kathryn Mulligan, fully vaccinated and living in New York City, developed her breakthrough case on Dec. 17. She had attended a few work functions that week and later learned many colleagues had tested positive.

Her illness began with a scratchy throat. By the evening, she had developed a 102-degree fever. Her condition lasted 8 days, and each day brought on new symptoms — a headache and vertigo, a deep cough, and finally, sinus pressure and congestion.

“But I was OK. It was like having a bad cold flu,” Mulligan told Healthline.

With Omicron, a variant that is believed to be less virulent than previous variants like Delta and Alpha, combined with the protection provided by the vaccines, the percentage of cases that are mild is thought to be even higher.

Because so many people are taking at-home rapid tests, which are not recognized in official case counts, it’s difficult to know precisely how many COVID-19 infections end up being mild.

“At this stage of the pandemic, the underreporting is likely due to multiple factors: at-home testing kits which go unreported; not seeking out testing because the wait time for results can be days, or not seeking out testing because you don’t have the original constellation of COVID-19 symptoms,” says Dr. Jose Mayorga, executive director of the UCI Health Family Health Centers and assistant clinical professor of the Department of Family Medicine at UCI School of Medicine.

According to Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, California, the severity of each infection depends on viral factors — such as the viral load and which variant the person was exposed to — and host factors, such as whether a person has immunity or underlying health conditions.

Immunity is the most important contributing factor behind the severity of infection, says Cutler.

“Vaccines and prior illness contribute to immunity. Age, illness, poor nutrition, obesity, diabetes, and numerous medical conditions can also impair immunity, causing more severe COVID,” Cutler said.

In addition, Omicron appears to spare the lungs but causes more upper-respiratory symptoms.

Building evidence suggests that people with Omicron generally, but not always, have fewer severe outcomes than people with Delta. The study, which has not yet been peer-reviewed, found people with Omicron were also hospitalized for fewer days and required less oxygen.

This does not mean that the virus is no longer a threat.

The number of cases recorded during the Omicron wave has overwhelmed hospitals treating COVID-19 patients and others who developed a mild case but required hospitalization for other health reasons.

“Remember, any illness causes stress and an inflammation response from our body. This response can be harmful, causing uncontrolled sugar among diabetics or possibly heart attacks in patients with heart disease,” said Mayorga.

In addition, while Omicron doesn’t seem to invade the lungs as much as other coronavirus variants, in some patients, it can still cause severe upper airway issues, says Mayorga.

Scientists are researching why some people diagnosed with COVID-19 experience long-haul symptoms such as fatigue, breathing problems, insomnia, and concentration issues.

But the risk of long COVID appears to be declining with the availability of vaccines.

Research has found that the vaccines, which help prevent severe illness and keep infections milder in most people, may significantly reduce people’s risk of developing long COVID.

A pre-print report recently found a substantial decrease in reporting long-haul symptoms in fully vaccinated people. People fully vaccinated are no more likely to report long-haul symptoms than people who have never been exposed.

In other words, vaccination may bring the risk of long COVID back to baseline.

It’s too early to clearly understand how milder cases contribute to long COVID, but scientists will watch the long-term health effects in the months and years to come.

Just because an infection is mild “doesn’t mean you are not susceptible to a more serious issue in the future. Although many people are tired of this pandemic and feel that 20 months is enough, we still need to learn so much more about the long-term impacts on COVID-19 survivors,” says Mayorga.

The majority of vaccinated people who have received a booster shot and still contract SARS-CoV-2 will likely experience mild symptoms such as sore throat, headache, congestion, and depending on the variant, coughing and loss of taste or smell. This doesn’t mean the virus is no longer a threat — many will still be hospitalized for COVID-19 or other health problems the virus may trigger. It’s unclear why some people experience mild illness and others develop severe sickness. Still, doctors suspect the viral load and the variant the person is exposed to, along with the patient’s immune response and underlying health.