Background As vaccine roll-out continues across the globe as part of the efforts to protect humanity against SARS-CoV-2, concerns are increasingly shifting to the duration of vaccine-induced immunity. Responses to these concerns are critical in determining if, when, and who will need booster doses following full vaccination against SARS-CoV-2. However, synthesised studies about the durability of vaccine-induced immunity against SARS-CoV-2 are scarce. This systematic review synthesised available global evidence on the duration of immunity following full vaccination against SARS-CoV-2. Methods We searched through Psych Info, Web of Science, Scopus, Google Scholar, PubMed, and WHO COVID-19 databases for relevant studies published before December 2021. Five eligibility criteria were used in scrutinising studies for inclusion. The quality of the included studies was assessed based on Joana Briggs Institute’s (JBI) Critical Appraisal tool and Cochrane’s Risk of Bias tool—version 2 (RoB 2), while the reporting of the results was guided by the Synthesis Without Meta-analysis (SWiM) guidelines. Results Twenty-seven out of the 666 identified studies met the inclusion criteria. The findings showed that vaccine-induced protection against SARS-CoV-2 infections builds rapidly after the first dose of vaccines and peaks within 4 to 42 days after the second dose, before waning begins in subsequent months, typically from 3 to 24 weeks. Vaccine-induced antibody response levels varied across different demographic and population characteristics and were higher in people who reported no underlying health conditions compared to those with immunosuppressed conditions. Conclusions Waning of immunity against SARS-CoV-2 begins as early as the first month after full vaccination and this decline continues till the sixth month when the level of immunity may not be able to provide adequate protection against SARS-CoV-2. While the evidence synthesised in this review could effectively inform and shape vaccine policies regarding the administration of booster doses, more evidence, especially clinical trials, are still needed to ascertain, with greater precision, the exact duration of immunity offered by different vaccine types, across diverse population characteristics, and in different vulnerability parameters. Registration The protocol for this review was pre-registered with the International Prospective Register of Systematic Reviews [PROSPERO] (Registration ID: CRD420212818).

1. Seed-based ecosystem restoration has huge potential to restore degraded drylands. However, fewer than 10% of directly sown seeds transition to established seedlings. One of the potential factors restricting plant establishment in degraded soils is the low abundance and diversity of native soil micro-organisms.In this study, we investigated whether returning indigenous bacteria and cyanobacteria consortia to degraded dryland soils improved seedling emergence, survival and growth of native plants.2. We inoculated 'culturable whole soil' native heterotrophic bacteria and biocrust cyanobacteria individually and as a mixed inoculant into extruded pellets containing Acacia inaequilatera (Fabaceae) and Triodia epactia (Poaceae) seeds. The pellets were planted in an active minefield for 28 weeks and seedling emergence and total biomass of plants were determined.3. Cyanobacteria and bacteria inoculants increased the emergence of A. inaequilatera by 55% and 48%, respectively. Seedling emergence in T. epactia was increased by 20% by cyanobacteria but was not increased by bacteria. The only effect of inoculation on seedling survival or mass per surviving seedling in either species was an 11% reduction of the growth of T. epactia seedlings that were inoculated with cyanobacteria. Synthesis and applications:Our results suggest that the benefit of microorganisms on plant establishment is both species specific and life stage specific, with particularly strong benefits in the early stages of recruitment. Our experiment was conducted under shade and with additional water, so a worthwhile future direction would be to quantify the effect of inoculation under unmodified

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