Cases of persistent cough, fever and Covid-like symptoms are on rise in the last few days across the country and experts say it may be linked to H3N2 influenza, a subtype of virus that causes flu and leads to more cases of hospitalisations compared to other strains. While the fever in most of the cases lasts for a few days, cough could persist for up to three weeks. The symptoms are related to upper airway including persistent cough, headache, fever, and sinus-related symptoms. Considering Covid hasn't completely vanished, and one needs to be sure, testing is important. However, there are some differences in the symptoms and incubation period of influenza and Covid-19 that can help you differentiate. (Also read: H3N2 influenza in India; tips to prevent infection while playing Holi)
"Both Influenza and Covid are viral illnesses, but they are totally different in terms of viral families. Currently, in India, there is a surge of the Influenza A family variant H3N2 among adults and Influenza B and Adenoviral infections among paediatric age groups. This pattern is mainly as a result of the last few years, as we have not been exposed to subclinical influenza infections due to masking, and the entire focus being on Covid," says Dr. Shivanshu Raj Goyal, Consultant, Respiratory Pulmonology & Sleep Medicine at Artemis Hospitals, Gurgaon.
Dr. Kuldeep Kumar Grover, Head of critical care & Pulmonology - CK Birla Hospital, Gurgaon says fever, chills, cough and cold are common in both while shortness of breath can be experienced more in case of Covid than influenza. Dr Grover adds that headache, muscle aches are common in both, while fatigue is more in Covid. Apart from this stuffiness of nose, sneezing, sore throat, loss of smell is seen in both the viral infections. Earache, nausea, diarrhoea are again common symptoms of both Covid and H3N2 influenza.
"Influenza and Covid are both contagious viral illnesses which cause a range of symptoms from no symptoms to mild cough and cold to severe illness affecting lower respiratory tract. The virus can also cause fever, body like headache, vomiting, diarrhoea and loss of taste and smell. The clinical features and investigations and radiology findings are also very similar in both the viruses.
Influenza shows more seasonal trend," says Dr Vineeta Taneja - Director - Internal Medicine- Fortis hospital Shalimar Bagh.
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A cough that just doesn’t go away
"In terms of symptoms, at present, most patients with influenza have presented with upper airway symptoms such as persistent cough, headache, fever, and sinus-related symptoms. After the initial period, fever settles, and cough persists for at least 2 to 3 weeks. This makes patients very miserable in terms of continuous coughing and throat discomfort. Most patients have been taking cough syrups and anti-allergic," says Dr Goyal.
Dr Grover says influenza has shorter incubation time and is more like a common viral infection. Symptoms may appear very fast in patients when they get infected, and the incubation period can be around 24 hours and the patient is likely to have upper respiratory symptoms. In case a person is diabetic, or old and has other such morbidities, they may experience more serious symptoms.
The incubation period for influenza is 1-4 days, while that of Covid is around 1-14 days.
Vaccines for Covid and Flu
To prevent influenza, one must get their flu shots while to cut the risk of Covid-19, one must get Covid vaccine as per protocol, says Dr Grover.
"Vaccinations place a very important role in preventing severe life-threatening. Illness is vaccination for influenza is the yearly vaccine and should be given to all children, adults with is commodities or everyone more than 60 years of age. Covid vaccination and boosters Are given to the entire population as a government led programme," says Dr Taneja.
How to differentiate between flu and Covid
"The only way to differentiate between flu and Covid is by doing a nasal examination to identify the viral antigens. It is important to differentiate between the two as the specific anti-viral medication required for the two were different," says Dr Taneja.
"As a saving grace, among adults, lung involvement has been rarely seen among influenza patients, in contrast to paediatric kids are getting sicker and often needing ICU admissions. Covid, in contrast, has got every kind of presentation, right from basic cough to severe pneumonia leading to respiratory failure and even death, as seen in the second wave of the Delta variant," says Dr Goyal.
Severity of Covid and influenza
"The severity of illness in both the influenza and the Covid cases range from very mild to very severe life-threatening illness and can depend on the immunity of the patient, age, commodities etc," says Dr Taneja.
Dr Goyal says it is crucial to maintain a high level of immunity by nutrition, hydration, and timely vaccination for Covid or annual flu.
"Please contact your doctor at the earliest and avoid over-the-counter medication abuse," concludes Dr Goyal.