Prevalence of Asymptomatic COVID-19 Infection Among Air Medical Crew

BACKGROUND: Air medical transport of COVID-19 patients is challenging and presents a high-risk exposure for many air medical crew. Previous investigations have concluded that routine PPE utilized by air medical crew using routing personal protective equipment is safe and effective at preventing symptomatic COVID-19 infections. However, it is unclear to what extent providers may be exposed, contract COVID-19, and remain asymptomatic but potentially contagious. Previous reports suggest up to 6.4% of infected health care personnel are asymptomatic. METHODS: We conducted an IRB approved, primary mixed-methods research study that tested for COVID-19 antibodies in a cohort of participants previously surveyed regarding COVID-19 symptoms. Written consent was obtained by all participants. ELISA testing was performed at the University of New Mexico Center for Global Health Laboratory. Testing included measuring for COVID-19 antibodies in a manner that was independent of vaccination status. Participants also filled out a secure electronic survey to aide in the qualitative data collection and analysis. RESULTS: There were 42 participants. Labs samples were obtained between June 2021 and October 2021. Of the 42, 40 were vaccinated (95.2%) and 2 were unvaccinated (4.8%). Of the 40 who were vaccinated, 1 person had the 2-part Moderna vaccine, the rest had the 2-part Pfizer vaccine. 10 of 42 (23.8%) had experienced potential symptoms of COVID-19 at some point in time but had never had a positive test and 32 (76.2%) never experienced any symptoms. Of the 42, 4 had a positive ELISA test for COVID-19 antibody for a positivity rate of 9.52%. Out of the 4 subjects that tested positive, 3 (75%) never experienced any symptoms. CONCLUSION: While the routine use of PPE has been proven to be effective in protecting air medical personnel from symptomatic COVID-19 infection, asymptomatic infection remains a concern. We found that 3 out of 4 that tested positive were asymptomatic. This is significant considering asymptomatic infection poses a risk to air medical crew, patients, coworkers, families, and the general public. Further investigation is required to better ascertain potential gaps in protective equipment or other latent sources of infection that pose risks to air medical crew.