Properly constructed, installed and maintained rotary heat exchangers have almost zero transfer of particle bound pollutants including air-borne bacteria, viruses and fungi. There is no evidence that virus-bearing particles would be an object of carry over leakage, so there is no need to switch off rotary heat exchangers. Normal operation of rotary heat exchangers makes it easier to maintain adequate ventilation rates, while ensuring system efficiency and comfort, as recommended in BESA VG002 V4 https://www.thebesa.com/media/837990/besa-guidance-vg002-v4.pdf
