HYDERABAD: It’s not one, but a series of at least five respiratory viruses have dominated the infection scenario for the past five months, causing mild to severe illness.
Doctors began observing unusual cases of fever, cough and cold distinct from Covid-19 in September 2022, but most went undiagnosed at the time. Now official data shows it was a bundle of respiratory viruses, including swine flu, that caused hospitalizations and deaths.
Official data shows that alongside the Covid-19 virus, swine flu (H1N1) that caused the 2009 pandemic, 1968 H3N2 that made Hong Kong flu famous, and the seasonal Victoria and Yamagata lines of influenza B -Viruses with each of these viruses circulating have dominated the infection charts at some point.
Health experts are not ruling out the presence of H3N2v, a descendant of the 2009 pandemic swine flu, as human-to-human transmission has been reported from some parts of the world, including the United States. However, official data is silent about the H3N2v strain.
While Covid-19 was at times nearly erased from the infection scenario, the long-forgotten swine flu unknowingly filled the void by infecting more people. Even the Victoria line topped the infection charts for several weeks. However, as the focus has been more on Covid-19, these equally serious respiratory viruses have gone unreported.
Although influenza A strain H3N2 currently dominates the infection charts, its sister influenza B lineage Victoria has also been circulating in significant numbers since January. Originally a milder strain, influenza B has been late in growing in severity and causing hospitalizations, doctors warn.
Weekly data from the Indian Council of Medical Research (ICMR) shows that H3N2 has taken the lead lately, pushing Covid-19 aside. The latest official statistics show, of the samples tested this week (March 5-11), 37 from H3N2, 10 from Victoria, eight from Covid-19 and one from swine flu.
Before H3N2 became dominant since January 1 of this year, swine flu was the leading cause of respiratory infections between April 18, 2022 and December 31, 2022. However, H3N2 was present throughout 2022 but at low levels with fewer infections. The Covid-19 was dominant from December 27, 2021 to February 27, 2022 and peaked in mid-January 2022.
The Victoria line caused more infections between August 16, 2021 and January 2, 2022, with cases peaking in September 2021.
Although non-Covid-19 respiratory viruses attracted attention earlier this month with rising cases of cough and cold, as early as September 2022 several doctors published on CME India, an online medical education portal, that they had treated patients with viral pneumonia. But they could not diagnose the cause. They had described it as a far more dangerous flu than Covid-19. One of the doctors, Dr. Ravi Premchand said he saw 10 such cases in one month, with two deaths.