In a recent study published in Science Advances, researchers evaluated the impact of mucosal versus intramuscular vaccine immunization on airborne infection and transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Syrian hamsters.
Background
SARS-CoV-2 causes coronavirus disease 2019 (COVID-19), identified in 2019, with vaccines developed by 2020 targeting the virus’s spike protein, showing 75-95% effectiveness against similar variants.
However, variants like Omicron reduced vaccine efficacy, leading to vaccine updates. SARS-CoV-2 primarily spreads through the air but can also be transmitted via contact.
Hamster studies on vaccine impact often focus on initial transmission, not reflecting real infection scenarios or assessing secondary transmission.
Further research is needed to fully understand mucosal vaccines’ long-term efficacy and mechanisms in preventing SARS-CoV-2 transmission in diverse populations and real-world settings.
About the study
This study evaluated the effects of mucosal and systemic immunization on SARS-CoV-2 transmission using Syrian hamsters. Hamsters were vaccinated intranasally with chimpanzee adenoviral-vectored vaccine (ChAd-CoV-2-S) or intramuscularly with remnant BNT162b2 (BioNTech and Pfizer COVID-19 vaccine) and then exposed to SARS-CoV-2-infected hamsters.
Viral titers in the upper and lower airways were measured to determine transmission. Primary contact hamsters that remained uninfected were excluded. Hamsters were randomly assigned to vaccination or donor/contact groups.
Vero cells expressing human transmembrane protease serine 2 (TMPRSS2) and angiotensin-converting enzyme 2 (ACE2) were cultured to prepare the virus.
Recombinant SARS-CoV-2 (WA1/2020 D614G) was confirmed by sequencing. All procedures involving SARS-CoV-2 were conducted in Biosafety Level 3 (BSL-3) facilities.
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