Do I have COVID or the flu? How to tell the difference

October 11, 2021

Some researchers are predicting that due to low levels of social contact and potentially low levels of immunity, we could be headed for a bad flu season this winter. So here’s what you need to know about the flu, its symptoms, and how to keep yourself safe this winter. 

What is the flu?

Flu is a contagious respiratory disease caused by influenza viruses. There are two main types of flu virus, along with various subtypes, and they can jump between humans and animals. Like COVID-19, flu is spread by droplets released when an infected person coughs, sneezes or talks. 

Right now, it’s thought the symptoms of flu include fever, body aches, fatigue, cough, sore throat, headache, loss of appetite, and sometimes an upset stomach.  

Although the disease is relatively mild for most people, it can be more severe for very young children, frail older people, and people with underlying illnesses. In some cases, flu can cause severe complications, including pneumonia, which can be fatal.

How is flu different from COVID-19?

Flu and COVID-19 are caused by two different and very distinct viruses. However, they do cause similar symptoms. As we know, thanks to ZOE COVID Study app contributors,  the most common COVID-19 symptoms include headache, runny nose, sneezing, sore throat, fever, and cough, which are all common flu symptoms. So how do we tell the difference?

Our research shows that loss of smell (anosmia) or loss of taste is still one of the most important predictors of testing positive for COVID-19, so it’s an important symptom to look out for.  

Even if you’re vaccinated, you can still catch COVID-19. COVID symptoms can feel a lot like a cold or the flu - if you’re newly unwell we recommend you get a PCR test to rule COVID out. If you’re a ZOE COVID Study contributor and report any of the 20+ symptoms consistent with COVID-19, you’ll be offered a test through the app.

If you’re feeling unwell for any reason - whether it’s a cold, flu or COVID-19 - it’s a good idea to stay home and avoid spreading your germs to others.

Should I be worried about the flu this year?

Every year, winter flu outbreaks hospitalise thousands of people in the UK. The number of flu-related deaths varies each year, depending on which strains of the virus are circulating. 

In a typical year, around 7,000 people die in the UK as a result of flu with most deaths happening in people over 65. However, in a bad flu year, deaths can reach 25,000 or more.  

Over the past two winters, COVID measures such as mask-wearing, social distancing and lockdowns have reduced flu outbreaks. Last winter, only 40 hospitalisations due to influenza were reported across England.

With low levels of circulating flu over the past couple of years, experts are speculating that our immunity against influenza viruses has diminished. As COVID restrictions are lifted, increased virus circulation combined with low immunity levels could mean we are in for a bad flu season this year. 

What can I do to avoid catching the flu?

The best way to protect yourself against the severe effects of flu is to get a flu vaccination. 

In an attempt to mitigate the effects of flu this winter, the government have extended the free annual flu vaccination program to include more people than in previous years, including over 50s, children aged 2-16, pregnant women, people with underlying health problems, people in residential care, health and social care workers, and carers.  

If you aren’t eligible for a free flu vaccine, you may still be able to pay to receive one at your local pharmacy. The flu jab takes 10-14 days to become effective, so it is best to plan ahead and get your jab early, before the flu season starts. 

To protect yourself from flu, you should also practice the basic public health measures we have relied upon in the fight against COVID. This means frequent hand washing, covering your mouth if you cough or sneeze, mask-wearing, maintaining a social distance and staying home if you are sick.

How effective are flu jabs and should I get one?

The influenza virus that causes flu mutates quickly and can jump between species, causing rapid changes that can help it evade immune responses. New flu vaccines are made each year to target the strains of influenza that are currently circulating. However, because the jab is based on predictions, effectiveness can vary.

Despite this uncertainty, the flu jab is very safe and is still the best way to protect yourself and others against the flu. The vaccine reduces your risk of contracting and spreading major flu strains. Even if you are unlucky and still contract the flu after getting the jab, it is likely to be much milder than if you were unvaccinated. Even though vaccination may not be 100% effective, it is still well worth getting your flu jab. 

Help vital research by logging your flu jab

The ZOE COVID study is ideally placed to monitor flu, and this year we will be using your symptom reports to track the impacts of both COVID-19 and flu. We have updated the app so you can log your flu jab alongside your COVID vaccinations, which will help us monitor how vaccines impact the spread of flu and COVID-19. 

Flu is just the start of our expanded studies and soon we’ll be looking into a wider range of health concerns as part of our wider health studies programme. To take part in these studies, you’ll need to opt in via the app. So head to the app today, opt in on the home menu and keep an eye out for new studies.

If you haven’t already, download the app, log your vaccines and take a few minutes each day to report how you’re feeling, so we can help beat COVID and winter flu.

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