Nanomaterials for prevention and therapy of COVID-19. Integrating nanomaterials into personal protective equipment (PPE) can prevent the entrance of SARS-CoV-2 in the respiratory system. Nanomaterials could also be used to deliver drugs to the pulmonary system via inhalators. Cellular binding of viral particles at the alveoli can be inhibited using targeted nanoparticles (NPs) against angiotensin-converting enzyme 2 (ACE2) receptors or viral S protein. Various mechanisms can be used to inactivate viral particles systemically such as using neutralizing NPs or photocatalytic nanomaterials. Nanomaterial-based vaccines or immunomodulation can be used to prevent SARS-CoV-2 infection or even to boost the immune response during infection. PDT, photodynamic therapy.