Even brief e-cigarette use can cause lasting lung damage and weaken defences against respiratory viruses, a new study suggests.Researchers led by National Jewish Health exposed human lung cells and precision-cut lung tissue to e-cigarette vapor. Within 24 hours, vapor damaged the protective barrier of the distal lung, triggered cellular stress, impaired repair and increased cell death.Signs of lung stress persisted 10 days after a five-day exposure ended. Prior vaping also increased SARS-CoV-2 viral burden and suppressed several antiviral genes after infection."Our findings suggest that even short-term vaping exposure can initiate injury in the deepest and most delicate regions of the lung," said senior author Dr Irina Petrache. The findings will need confirmation in human studies.The study, published in JCI Insight, points to biological mechanisms that may explain why vaping has been linked to lung injury. The authors noted repeated exposure could contribute to chronic lung disease.