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The number of people experiencing symptoms of fever, cold, throat pain and cough over the last few weeks have been steadily on the rise. The Government of India has ramped up the testing and surveillance to assess the increase in respiratory infections and related hospital admissions. It has been observed that over 50 % of the admissions in the hospitals with severe acute respiratory illness is due to H3N2 and the increase in Covid-19 cases are due to the highly transmissible sub-variants of Omicron, XBB.1.16 and XBB.L.5.
Symptoms of both infections present very similarly with fever, cough, cold, throat pain, body pain and difficulty in breathing. Therefore, it is necessary to practice hand hygiene, wear masks, and physically distance to prevent transmission. Those experiencing breathlessness and difficulty in breathing need to seek medical attention without delay.
Similar situations of coinfections with Covid-19 and Influenza virus have been reported across different countries in the world. Here is a report from Brazil last year https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8759102/ where the high vaccination rates for SARS-CoV2 had led to the reduction in the use of non-pharmacological preventive measures such as face-masks, mass gathering restrictions and social distancing, leading to the population becoming more flexible and even neglectful.
The Omicron subvariants of Covid-19, which is highly transmissible, combined with low vaccine coverage for Influenza, whose H3N2 strain is not yet part of the current vaccine, had led to increase in the emergence and growth of coinfection cases. Influenza is a negative sense segmented RNA enveloped virus that belongs to the Orthomixoviridae family. Importantly, Alpha influenzavirus and Beta influenzavirus are known to infect humans. They present two main proteins in their envelope, Hemagglutinin (HA) and Neuraminidase (NA). These proteins commonly mutate by two major events known as antigenic drifts and shifts; these are the main cause of outbreaks worldwide.
To monitor the situation closely, the Government of Karnataka has held a meeting with the members of Covid-19 task force to discuss the surveillance strategy and preparedness of the health care system. Advisories to effectively monitor and handle the situation are being drafted for the government’s perusal. Clinical guidance for management of Covid-19, H3N2 and coinfections have been issued to all the health care providers by the health ministry.
The challenge this wave of rising Covid- 19 infections presents to the health care workers lies in differentiating between Covid-19 and H3N2 infections along with identifying and managing co-infections.