Hospitals in parts of India–where the COVID-19 caseload has only just started to ebb–are seeing a sudden surge in cases of swine flu, and flu-like symptoms.

A recent survey conducted in the capital found that 41 percent of households in Delhi reported at least one member who is down with flu-like symptoms.

The same survey found that 80 percent of these cases turned out to be seasonal flu and 20 percent were swine flu, with less than 0.1 percent testing positive for COVID.

How do you tell the three apart? FIT breaks it down.

For a quick rundown, start with our symptom tracker below.

First, a quick look at the basics.

All three illness are caused by different viruses that behave similarly and primarily attack your respiratory system.

Swine Flu was first broke out in the US in 2009 where the viral infection jumped from pigs to humans.

According to Mayo Clinic, it is caused by the H1N1 strain of the flu (influenza) virus.

COVID-19 on the other, was first identified in China, is caused by the SARS CoV-2 virus and is thought to have dumped from bats to humans.

It was declared a global pandemic by the WHO on 11 March 2020.

Infectiousness

COVID-19 is far more infectious than swine flu and common seasonal flu.

But, it is hard to compare the COVID caseload to that of the flu as, for one there is no reliable data on the global caseload of swine flu, and secondly, cases of the flu aren't always reported or recorded.

Deaths

According to the US CDC's estimates between 1,51,700 to 5,75,400 people worldwide have died from swine flu.

Compare that to the devastating death toll of COVID-19 where around 4.4 Million people worldwide have succumbed to the illness so far.

Swine flu is now an endemic and clubbed with seasonal flu that comes around cyclically.

'We see that cases of swine flu usually spike every alternate year. It happened in 2019, and it's happening now, so it's not unexpected," says Dr Ravi Shekhar Jha, Additional Director and Head of Department, Pulmonology, Fortis Escorts Hospital Faridabad.

Though all three infections are caused by entirely different viruses, their symptoms can be eerily similar, making it difficult to diagnose them just on the basis of these.

The most common symptoms that occurs in those infected by either are,

• Fever

• Body ache

• Fatigue

• Headache

• Runny nose

• Cough

• Sore throat

• Chills

But there are some subtle differences in the way the symptoms present.

A few distinguishing symptoms of COVID-19 that are rare in cases of flu include

• Loss of smell and taste

• Breathlessness

• Rashes on the body

Vomiting, nausea and diarrhoea too are very common in COVID, although they can also occur in some severe cases of the flu (particularly in adults)

On the other hand, "While sneezing is quite common in seasonal flu and swine flu, it is very rare in COVID-19," says Dr Jha.

How long does it take for the illness to show up?

According to the US CDC (Centre for Disease Control and Prevention) person infected with an influenza virus, including that of swine flu will typically start showing symptoms within 1- 4 days.

In the case of COVID-19, it could take anywhere between 5 -14 days after infection for the symptoms to show up.

Because of the significant overlap in symptoms, only specific tests can confirm the illness.

For all three viral infections, the test conducted are pretty much the same. Dr Jha explains this, saying, "The tests are done using throat and nose swabs which are analysed using genomic sequencing. What differs is what the tests look for."

Given the low risk associated with general seasonal flu, your doctor will not ask you to take a test unless you have severe complications, have been hospitalised or at a high risk of flu-related complications.

One of the reasons why COVID has been more damaging is that we didn't and still don't have a sure shot treatment and were left pulling at straws. Symptom management is the most common route of treatment for all three infections.

Influenza & Swine Flu: The flu, in most cases resolves itself within a few days. Sometimes, however, the infection can become severe and cause other complications including pneumonia.

Most flu, including the swine flu can be treated using antiviral flu drugs like oseltamivir phosphate.

COVID-19: Although some treatments like certain monoclonal antibody cocktails are available, they have only found to be effective in very limited cases.

There are vaccines available for both the flu and COVID-19. "Annual influenza vaccines have been found to be just as effective in preventing swine flu," adds Dr Jha.