Infection-Induced Immunity Is Associated With Protection Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Decreased Infectivity

Abstract

Background The impact of infection-induced immunity on SARS-CoV-2 transmission has not been well established. Here we estimate the effects of prior infection induced immunity in adults and children on SARS-CoV-2 transmission in households. Methods We conducted a household cohort study between March 2020-November 2022 in Managua, Nicaragua where when one household member tests positive for SARS-CoV-2, household members are closely monitored for SARS-CoV-2 infection. Using a pairwise survival model, we estimate the association of time period, age, symptoms, and prior infection with secondary attack risk. Results Overall, transmission occurred in 70.2% of households, 40.9% of household contacts were infected, and the secondary attack risk ranged from 8.1%1 to 13.9% depending on the time period. Symptomatic infected individuals were more infectious (RR 21.2, 95% CI: 7.4-60.7) and participants with a prior infection were half as likely to be infected compared to naïve individuals (RR 0.52, 95% CI:0.38-0.70). In models stratified by age, prior infection was associated with decreased infectivity in adults and adolescents (SAR 12.3, 95% CI: 10.3, 14.8 vs 17.5, 95% CI: 14.8, 20.7). However, while young children were less likely to transmit, neither prior infection nor symptom presentation was associated with infectivity. During the Omicron era, infection-induced immunity remained protective against infection. Conclusions Infection-induced immunity is associated with decreased infectivity for adults and adolescents. While young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics.

Mucosal vaccines for SARS-CoV-2: triumph of hope over experience

“… 49 This was mirrored in a household transmission study showing upon breakthrough infection, incidences of onward transmission were equally as likely from individuals that were previously infected or not. 50 Taken together, these epidemiological findings indicate that mucosal responses seeded by prior infection can mediate durable protection against breakthrough infections but are unlikely to impede onward transmission upon acquisition of infection. Moreover, these findings provide a proxy to assess responses by mucosal vaccine candidates.…”

A mini review of reinfection with the SARS‐CoV‐2 Omicron variant

“…A household cohort study conducted in Managua, Nicaragua from March 2020 to November 2022 found that prior infection was associated with decreased infectivity in adults and adolescents. The secondary attack risk was 12.3 (95% CI: 10.3−14.8) for those with prior infection compared to 17.5 (95% CI: 14.8−20.7) for naive individuals 44 . Additionally, participants with prior infection were half as likely to be infected compared to those who were naive (RR 0.52, 95% CI: 0.38−0.70) 44 …”

“…The secondary attack risk was 12.3 (95% CI: 10.3−14.8) for those with prior infection compared to 17.5 (95% CI: 14.8−20.7) for naive individuals. 44 Additionally, participants with prior infection were half as likely to be infected compared to those who were naive (RR 0.52, 95% CI: 0.38−0.70). 44 The reduced infectivity in reinfection may be due to antibodies neutralizing a portion of the virus during the second infection.…”

“…44 Additionally, participants with prior infection were half as likely to be infected compared to those who were naive (RR 0.52, 95% CI: 0.38−0.70). 44 The reduced infectivity in reinfection may be due to antibodies neutralizing a portion of the virus during the second infection.…”

“… 44 Additionally, participants with prior infection were half as likely to be infected compared to those who were naive (RR 0.52, 95% CI: 0.38−0.70). 44 …”