Covid symptoms likely to depend on vaccination history, new study shows

Fever now only seen in rare unvaccinated cases, with shortness of breath and loss of taste on the wane

The type of symptoms of Covid-19 a patient gets can depend on what vaccinations they have had in the past, according to new research.

Researchers from King’s College London, Massachusetts General Hospital, Harvard and Stanford University analysed data on vaccinated and unvaccinated people with Covid-19 to evaluate symptoms as part of the ZOE Health Study that monitors virus trends.

Data was reported via a mobile app, with more than 4.8 million people contributing worldwide.

Fully vaccinated people most commonly reported a sore throat, persistent cough, runny or blocked nose and headaches.

Meanwhile, those with a single dose reported headache, sneezing, runny nose, cough and sore throat. The unvaccinated, however, had all the symptoms as well as a fever.

The study also indicated a decline in shortness of breath and loss of taste and smell — two key symptoms in the early stage of the pandemic.

Dr Mahmoud Hamed, a pulmonologist at Al Sharq Hospital in Fujairah said the study results reflected what he was seeing in his patients.

“The severity of symptoms is not related to what vaccine the patient has taken, but how many doses they have had,” he said.

“We are not seeing sneezing as a symptom in people with one or two vaccines, and those with three doses have blocked noses and persistent coughing.

“Those who are unvaccinated tend to get the fever, but that is the exception.

“The duration of symptoms in those with three doses is generally less than those who have received one or two doses, and substantially less than those unvaccinated.

“Fever is a very common symptom [in this group] as a common index of viral load, this is the biggest difference in those unvaccinated.”

The ZOE Covid Study app has tracked virus symptoms based on daily user-entered data since 2020.

Data did not account for which Covid-19 variant caused the infections, how many infections were first-time experiences, whether a user received booster doses, patient demographic information, or the severity of symptoms.

The most effective protection against the virus now includes a new Omicron-specific booster shot that is more effective against today’s Covid strains than the original vaccines.

Early data suggests a booster can top up antibodies ahead of an impending winter viral surge.

While new Omicron variants BQ1 and XBB bring a greater risk of reinfection, the World Health Organisation’s technical advisory group did not consider either to carry an extra threat of more severe symptoms.

Dr Ahmed Khairy, chair of medical specialities at NMC Royal Hospital in Khalifa City, said vaccines were generally still doing their job.

“Vaccines are not 100 per cent to prevent infection but to make the symptoms less severe,” he said.

“Usually, vaccinated patients have less severe symptoms than those who are not, fewer complications and recover faster.

“The illness in vaccinated people is also often much shorter.

“Symptoms from Covid-19 now are generally mild, and there is a low risk of complications.

“Flu is also now circulating, but we still have to do a PCR test to understand if it could be Covid.

“The effect of vaccines administered 18 months or so will still be there but those more vulnerable groups are still advised to take a booster.”