Effectiveness and protection duration of Covid-19 vaccines and previous infection against any SARS-CoV-2 infection in young adults

Abstract

Data on effectiveness and protection duration of Covid-19 vaccines and previous infection against general SARS-CoV-2 infection in general populations are limited. Here we evaluate protection from Covid-19 vaccination (primary series) and previous infection in 21,261 university students undergoing repeated surveillance testing between 8/8/2021–12/04/2021, during which B.1.617 (delta) was the dominant SARS-CoV-2 variant. Estimated mRNA-1273, BNT162b2, and AD26.COV2.S effectiveness against any SARS-CoV-2 infection is 75.4% (95% CI: 70.5-79.5), 65.7% (95% CI: 61.1-69.8), and 42.8% (95% CI: 26.1–55.8), respectively. Among previously infected individuals, protection is 72.9% when unvaccinated (95% CI: 66.1–78.4) and increased by 22.1% with full vaccination (95% CI: 15.8–28.7). Statistically significant decline in protection is observed for mRNA-1273 (P < .001), BNT162b2 (P < .001), but not Ad26.CoV2.S (P = 0.40) or previous infection (P = 0.12). mRNA vaccine protection dropped 29.7% (95% CI: 17.9–41.6) six months post- vaccination, from 83.2% to 53.5%. We conclude that the 2-dose mRNA vaccine series initially offers strong protection against general SARS-CoV-2 infection caused by the delta variant in young adults, but protection substantially decreases over time. These findings indicate that vaccinated individuals may still contribute to community spread. While previous SARS-CoV-2 infection consistently provides moderately strong protection against repeat infection from delta, vaccination yields a substantial increase in protection.

Evaluation of Waning of SARS-CoV-2 Vaccine–Induced Immunity

“…Of these, we included 40 studies in our analysis (eFigure 1 in Supplement 1). Estimates Original estimates of VE reported in these articles were obtained as a result of test-negative case-control studies (n = 23), [9][10][11][12][13][14][15][32][33][34][35][36][37][38][39][40][41][42][43][44][46][47][48] case-control studies (n = 1), 16 or cohort studies (n = 16) [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]45 assessing the difference in incidence of SARS-CoV-2 infection between vaccinated individuals and a certain reference group. A detailed description of different reference groups, end and of the waning rate (w) are reported in eTables 7 and 8 in Supplement 1, along with the corresponding estimates obtained for the mean half-life of the vaccine-induced protection against the 2 considered end points.…”

The impact of retrofitted ventilation approaches on long-range airborne infection risk for lecture room environments: design stage methodology and application

“…architects or engineers) to make some decisions about ventilation design at the early design stages. In addition to this, it should be noted that vaccination has a key role to play in reducing the spread of viral pathogens, such as COVID-19, in the community [ [24] , [25] , [26] ] and it can have a substantial effect in reducing the need for other infection prevention control measures [ 27 ]. However, there are limitations to this as the sole approach to infection prevention and control as, for example, protection from infection from subsequent variants of COVID-19 (or other airborne viruses) may not be guaranteed, where current evidence for COVID-19 suggests that protection from reinfection decreases after vaccination [ 24 , 25 ].…”

Evaluating the Virology and Evolution of Seasonal Human Coronaviruses Associated with the Common Cold in the COVID-19 Era

“…As described above, common cold HCoVs cause seasonal disease and lack long-term protection, despite the presence of broadly recognizing antibodies [ 119 ]. With increases in vaccination and regular vaccine boosters, the number of cases and severity of disease may become more manageable with time [ 131 ].…”