This has been written about before, however there still seems to be a lack of clarity about the best practices for operating Ducted HVAC systems. Its obvious that these same issues affect other countries in the same ways and that there is general agreement that Ventilation systems need to be looked at professionally with the right recommendations, and as we said in our previous article about increasing Ventilation rates
This article on a US online trade magazine does address this issue quite well can-hvac-systems-spread-the-covid-19-virus?
No point in us saying anything else on this matter other than each system is different in terms of what should and shouldn't be done. There is however a general agreement in all countries that retrofitting existing systems with either BiPolar Air Purification or UV lights into the AHU's or Ducted systems.
The experts all agree that increasing Ventilation rates makes sense, but it isnt always as you first think. Its isnt all about replacement Air Filters either, as increasing the filtration level can cause air flow problems. Simple answer - Get expertise!