Can I replace my basic filter with a ‘HEPA’ filter to capture viruses?

HEPA filters can be effectiveness in filtering out viruses however the system needs to be designed with these filters in mind.  HEPA filters should only be used in systems specifically designed for use with HEPA type filters, otherwise there is a high possibility of air leaking around the HEPA filter, rendering the air filtration inefficient, or reducing the rate of supply of fresh air through increased resistance. This advicse is taken from CIBSE COVID-19 Ventilation guidance version 3.

https://www.cibse.org/coronavirus-covid-19/emerging-from-lockdown