Impact of COVID‐19 vaccination on transmission risk of breakthrough infections: Lessons from adapted N95 mask sampling for emerging variants and interventions

Abstract

This study used an adapted N95 mask sampling to understand the effect of COVID‐19 vaccination in the context of circulating variants on infected individuals to emit the virus into the air, a key risk factor of transmission. Mask, swab, and blood samples were collected from 92 COVID‐19 patients vaccinated (Covishield/COVAXIN‐partial/fully) or unvaccinated between July and September 2021 during the Delta‐dominated period in Mumbai. Mask/swab samples were analysed by RT‐PCR for viral RNA. Blood was evaluated for SARS‐CoV‐2 anti‐spike and nucleocapsid antibody responses. At < 48 hours of diagnosis, 93% of the patients emitted detectable viral RNA, with 40% emitting >1000 copies in 30‐minutes (high emitters). About 8% continued to be high emitters even after eight days of symptom onset. No significant difference was observed in emission patterns between partial, full and un‐vaccinated patients. However, when vaccinated patients were stratified based on spike protein neutralisation and nucleocapsid IgG, the group with moderate/high neutralisation showed a significantly lower proportion of high emitters and viral RNA copies than the group with no/low neutralisation, which further reduced in the group having anti‐nucleocapsid IgG. In conclusion, mask sampling showed that Delta infections were associated with greater virus emission in patients, which was significantly reduced only in vaccinated patients with moderate/high SARS‐CoV2 neutralisation, especially with evidence of past infection. The study demonstrated that mask sampling could be useful for understanding the transmission risk of emerging variants, screening vaccine/booster candidates and guiding control interventions. This article is protected by copyright. All rights reserved.

Does COVID-19 Vaccination Protect Contact Persons? A Systematic Review

“…On the other hand, the data sets in 12 studies described a higher viral load among the vaccinated compared to the unvaccinated. The difference was significant in three studies [27,30,38], not significant in eight studies [20,26,29,30,[33][34][35]40] and without reporting results of a statistical evaluation in two studies [22,32]. Among the boosted population (having received one dose of booster after the completion of the original course of vaccination), the effect of a lower viral load is insignificant within 61 to 120 days [49].…”