ABSTRACT
Background: The protective efficacy of prior coronavirus disease 2019 (COVID-19) with or without vaccination remains unknown. This study sought to understand if 2 or more messenger RNA (mRNA) vaccine doses provide additional protection in patients with prior infection, or if infection alone provides comparable protection. Methods: We conducted a retrospective cohort study of the risk of COVID-19 from 16 December 2020 through 15 March 2022, among vaccinated and unvaccinated patients of all ages with and without prior infection. A Simon-Makuch hazard plot illustrated the incidence of COVID-19 between groups. Multivariable Cox proportional hazards regression was used to examine the association of demographics, prior infection, and vaccination status with new infection. Results: Among 101 941 individuals with at least 1 COVID-19 polymerase chain reaction test prior to 15 March 2022, 72 361 (71.0%) received mRNA vaccination and 5957 (5.8%) were previously infected. The cumulative incidence of COVID-19 was substantially higher throughout the study period for those previously uninfected and unvaccinated, and lowest for those previously infected and vaccinated. After accounting for age, sex, and the interaction between vaccination and prior infection, a reduction in reinfection risk was noted during the Omicron and pre-Omicron phases of 26% (95% confidence interval [CI], 8%-41%; P = .0065) to 36% (95% CI, 10%-54%; P = .0108), respectively, among previously infected and vaccinated individuals, compared to previously infected subjects without vaccination. Conclusions: Vaccination was associated with lower risk of COVID-19, including in those with prior infection. Vaccination should be encouraged for all including those with prior infection, especially as new variants emerge and variant-specific booster vaccines become available.
ABSTRACT
RATIONALE: Severe acute respiratory syndrome Coronavirus 2 (SARS CoV-2), the virus that causes COVID-19, and consequent social distancing directives have been observed to negatively impact social relationships but the impact of these changes on the quality of social relationships at a population level has not been explored. OBJECTIVE: To evaluate changes in social relationships in a U.S. population sample during a time of social distancing. METHODS: We deployed a matched, longitudinal survey design of the National Institutes of Health Adult Social Relationship Scales to assess the social aspects of emotional support, instrumental support, friendship, loneliness, perceived hostility, and perceived rejection from a time without social distancing (February 2018) to a time where social distancing directives were active (May 2020). Changes in social relationships were compared using paired t-tests, and generalized linear regression models were constructed to identify subpopulations experiencing differential changes in each subdomain of social relationships during social distancing. RESULTS: Within our sample population, individuals experienced an increased sense of emotional support, instrumental support, and loneliness, and decreased feelings of friendship and perceived hostility during a period of social distancing. Individuals with low self-rated health experienced a decreased sense of emotional support, and females experienced increased feelings of loneliness compared with males. CONCLUSIONS: Social distancing measurably impacts social relationships and may have a disproportionate impact on females and individuals with lower self-rated health. If novel emergent infectious diseases become more commonplace, social interventions may be needed to mitigate the potential adverse impact of social distancing on social relationships.