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BackgroundThe Coronavirus disease 2019 (Covid-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted accelerated vaccines development. Their use was prioritized to protect the most vulnerable, notably, the elderly. Because of fluctuations in vaccine availability, strategies such as delayed second dose and heterologous prime-boost have been employed. The effectiveness of these strategies in the frail elderly are unknown. MethodsIn this real-world vaccination study, under a government-decreed rationing strategy, elderly adults residing in long-term care facilities, with or without previously-documented SARS-CoV-2 infection, were administered homologous or heterologous mRNA vaccines, with an extended 16-week interval between doses. Clinical data and blood were serially collected during and after this interval period. Sera were tested for SARS-CoV-2-specific IgG antibodies (to trimeric S; RBD; nucleocapsid) by automated chemiluminescent ELISA. FindingsAfter a significant increase 4 weeks post-prime dose, there was a significant decline in anti-RBD and anti-S IgG levels until the boost dose, followed by an increase 4 weeks later. Previously uninfected individuals exhibited lower antibody responses up to 16 weeks post-prime dose, but achieved comparable levels to previously infected counterparts by 4 weeks post-second dose. Individuals primed with BNT162b2 exhibited larger decrease in anti-RBD and anti-S IgG levels with 16-week interval between doses, compared to those who received mRNA-1273. No differences in antibody levels 4 weeks after the second dose were noted between the two vaccines, in either homologous or heterologous combinations. InterpretationsThese interim results of this ongoing longitudinal study show that, among frail elderly, neither age, sex, nor comorbidity affect antigenicity of mRNA-based COVID vaccines, but previous SARS-CoV-2 infection and type of mRNA vaccine influenced antibody responses when used with a 16-week interval between doses. Homologous/heterologous use of mRNA vaccines was not associated with significant differences in antibody responses 4 weeks following second dose, supporting their interchangeability. FundingThis project was supported by funding from the Public Health Agency of Canada, through the Vaccine Surveillance Reference group and the COVID-19 Immunity Task Force (CITF).
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ObjectivesConcerns have been raised that the COVID-19 pandemic could increase risk for adverse mental health outcomes, especially in young adults, a vulnerable age group. We investigated changes in depression and anxiety symptoms (overall and severe) from before to during the pandemic, as well as whether these changes are linked to COVID-19 related stressors and pre-existing vulnerabilities in young adults followed in the context of a population-based cohort. MethodParticipants (n=1039) from the Quebec Longitudinal Study of Child Development reported on their depression and anxiety symptoms and completed a COVID-19 questionnaire during the first wave of the COVID-19 pandemic in the summer of 2020 (age 22 years). Assessments at age 20 (2018) were used to estimate pre-pandemic depression and anxiety symptom severity. ResultsWhile overall levels of depression and anxiety symptoms did not change, there was an increase in rates of severe depression (but not severe anxiety) from before (6.1%) to during (8.2%) the pandemic. Depressive and anxiety symptoms increased from before to during the COVID-19 pandemic among young adults with the lowest levels of symptoms before the pandemic, while they decreased among those with the highest levels of pre-existing symptoms. Youth who were living alone experienced an increase in depressive symptoms. Other COVID-19 related variables (e.g., loss of education/occupation, frequent news-seeking) and pre-existing vulnerabilities (e.g., low SES, low social support) were not associated with changes in depression or anxiety symptoms. ConclusionDepression and anxiety symptoms in young adults from Quebec in Summer 2020 were comparable to symptoms reported in 2018. Most COVID-19 related stressors and pre-existing vulnerabilities were not associated with changes in symptoms. However, the increased rate of severe depression and the increase in depression and anxiety symptoms among young adults with the least mental health symptoms before the COVID-19 pandemic are concerning.
