A population-based study from Spain has found that respiratory viral infections are common in people who die during winter months, but many of these infections are not diagnosed before death. This highlights potential gaps in current diagnostic testing and surveillance.
The researchers analyzed postmortem samples from 857 individuals over four influenza seasons (2016–2020). Using PCR testing, researchers looked for a range of respiratory viruses in swabs taken shortly after death.
More than one-third of individuals (36 percent) tested positive for at least one respiratory virus. The most common were rhinovirus (11 percent) and influenza (11 percent), followed by human coronavirus and respiratory syncytial virus (RSV).
However, most of these infections had not been identified before death. Influenza was listed as the cause of death in just 1.4 percent of cases, showing a clear difference between laboratory findings and recorded causes of death. Among those with influenza detected after death, only 17 percent had been diagnosed with influenza in the month prior.
The study also found that relatively few individuals had been tested before death. Only about 11 percent had undergone respiratory virus testing in the previous 30 days, suggesting that many infections may go unrecognized, particularly outside hospital settings.
The findings highlight the value of molecular diagnostic tools such as multiplex PCR, which can detect multiple viruses in a single test. The study also identified cases of co-infection, indicating that more than one virus can be present at the same time, especially in older or vulnerable patients.
These results also point to limitations in current surveillance systems. Mortality data and routine clinical testing may underestimate the role of respiratory viruses, as many cases are not confirmed before death. This is particularly relevant during peak winter periods, when virus circulation is highest.
Importantly, detecting a virus after death does not confirm it caused the death. However, the consistent gap between postmortem findings and clinical diagnoses suggests that respiratory infections may play a larger role in mortality than currently captured.
Overall, the study highlights the need for improved diagnostic strategies and more consistent testing, particularly in community and long-term care settings. For clinicians and laboratory professionals, it reinforces the importance of considering respiratory viral infections in vulnerable patients and the potential benefits of broader use of molecular diagnostics.
Newsletters
Receive the latest pathologist news, personalities, education, and career development – weekly to your inbox.
