When the global coronavirus pandemic began last year, influenza viruses mysteriously disappeared from global circulation. Some skeptics suspected that influenza had been simply reclassified as Covid-19, while journalists and ‘fact checkers’ claimed influenza was suppressed by face masks, social distancing and lockdown measures. Influenza viruses even disappeared in countries without any restrictions, which has not been the case in previous epidemics and pandemics,
Instead, influenza flu viruses were simply displaced in 2020 by the more infectious novel coronavirus. This displacement effect is well known from previous influenza pandemics: the 1918 flu virus was displaced by the 1957 flu virus, which in turn was displaced by the 1968 flu virus (see chart). The 2009 swine flu virus temporarily displaced previous flu viruses, but eventually couldn’t assert itself (see chart).
Even during the pandemic, more transmissible virus strains are repeatedly displacing previous coronavirus strains; eg the original Covid-19 strain being replaced with the UK “Kent” variant, and the current worry that the South African or Brazilian variants could become dominant strains in the UK. These are mutating and trying to evade the new vaccines. probably necessitating booster shots each autumn. as we do with the flu vaccine.
An interesting and open question is whether coronavirus might permanently suppress some or all of the existing influenza virus strains,. This might be a positive development , in that annual covid booster jabs could replace the annual flu vaccine jabs for the elderly. click full data source