Fareena Ruzaik Your question is valid and worth further study. To penetrate the ground water supply, you need to take into account soil sorption and microbial degradation/predation as well as depth of soils. A more immediate concern is water runoffs from heavy downpour or in unexpected cases flood (especially in this monsoon season for tropical countries).The decaying covid-19 bodies would be a huge source of the virus and if the water runoffs from mass graves for example Iran or Brazil would be significant as these waters can contaminate the source of water supply for human or animals and the latter can become future reservoir (think mink).
see
Article Coronavirus disease 2019 (COVID-19) outbreak: some serious c...
Have not seen yet but the biochemical interaction ongoing will really be a thing to behold especially if it would affect plant that grows around the spot positively or negatively
Normally burial is done at a level of 1.8 m from the surface. So areas with deeper water table for unconfined aquifers will not be affect. Areas with shallow water tables can have some kind of pollution of groundwater. Burial of bodies will not affect confined aquifers.