ABSTRACT
The emergence of the SARS-CoV-2 Omicron sublineages resulted in drastically increased transmission rates and reduced protection from vaccine-induced immunity. To counteract these effects, multiple booster strategies were used in different countries, although data comparing their efficiency in improving protective immunity remains sparse, especially among vulnerable populations, including older adults. The inactivated CoronaVac vaccine was among the most widely distributed worldwide, particularly in China, and South America. However, whether homologous versus heterologous booster doses in those fully vaccinated with CoronaVac induce distinct humoral responses and whether these responses vary across age groups remain unknown. We analyzed plasma antibody responses from CoronaVac-vaccinated younger or older individuals in central and south America that received a homologous CoronaVac or heterologous BNT162b2 or ChAdOx1 booster vaccines. We found that both IgG levels against SARS-CoV-2 spike or RBD, as well as neutralization titers against Omicron sublineages, were substantially reduced in participants that received homologous CoronaVac when compared to heterologous BNT162b2 or ChAdOx1 booster. This effect was specifically prominent in recipients older than 50 years of age. In this group, CoronaVac booster induced low virus-specific IgG levels and failed to elevate their neutralization titers against any omicron sublineage. Our results point to significant inefficiency in mounting protective anti-viral humoral immunity in those who were primed with CoronaVac followed by CoronaVac booster, particularly among older adults, urging a heterologous regimen in high-risk populations fully vaccinated with CoronaVac. One Sentence SummaryHomologous CoronaVac boosters do not improve neutralization responses against current VOCs in older adults in contrast to heterologous regimens.
ABSTRACT
BackgroundMental health has become one of the fundamental priorities during the COVID-19 pandemic. Situations like physical distancing as well as being constantly tagged as the most vulnerable group could expose older adults to mental and psychosocial burdens. Nonetheless, there is little clarity about the impact of the COVID-19 pandemic or similar pandemics in the past on the mental illness, wellbeing, and psychosocial health of the older population compared to other age groups. ObjectivesTo describe the patterns of older adults mental and psychosocial health related to acute respiratory disease propagated-type epidemics and pandemics and to evaluate the differences with how other age groups respond. Eligibility criteriaquantitative and qualitative studies evaluating mental illness, wellbeing, or psychosocial health outcomes associated with respiratory propagated epidemics and pandemics exposure or periods (COVID-19, SARS-CoV, MERS, and Influenza) in people 65 years or older. Data sourceOriginal articles published until June 1st, 2020, in any language searched in the electronic healthcare and social sciences database: MEDLINE, Embase, CINAHL, PsycINFO, Scopus, WHO Global literature on coronavirus disease database, China National Knowledge Infrastructure ( -CNKI). Furthermore, EPPI Centres COVID-19 living systematic map and the publicly available publication list of the COVID-19 living systematic review will be incorporated for preprints and recent COVID-19 publications. Data extractionTwo independent reviewers will extract predefined parameters. The risk of bias will be assessed. Data synthesisData synthesis will be performed according to study type and design, type of epidemic and pandemic, types of outcomes (mental health and psychosocial outcomes), and participant characteristics (e.g., sex, race, age, socioeconomic status, food security, presence of dependency in daily life activities independent/dependent older adults). Comparison between sex, race, and other age groups will be performed qualitatively, and quantitatively if enough data is available. The risk of bias and study heterogeneity will be reported for quantitative studies. ConclusionThis study will provide information to take actions to address potential mental health difficulties during the COVID-19 pandemic in older adults and to understand responses on this age group. Furthermore, it will be useful to identify potential groups that are more vulnerable or resilient to the mental-health challenges of the current worldwide pandemic.
