COVID-19 vaccination: a systematic review of vaccination strategies based on economic evaluation studies.

INTRODUCTION: Countries must employ the most efficient way to vaccinate their population with the COVID-19 vaccines, given the vaccines' low availability compared to its demand. This review aims to identify and compare the different COVID-19 vaccine delivery strategies employed internationally in the recent year based on the economic evaluation findings and subsequently to recommend the most cost-effective strategy among them. MATERIAL AND METHODS: A systematic review was conducted by examining online databases (Scopus, MEDLINE and Science Direct) to identify health economic evaluation studies of COVID-19 vaccines. Critical appraisal of studies was conducted using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS). RESULTS: A total of nine studies were selected for analysis. Results show two strategies that were cost-effective compared to its comparators: mass vaccination program compared to no vaccination and universal vaccination approach compared to a risk-stratified vaccination approach. Several other strategies were found to increase the cost-consequences in the COVID-19 vaccination program: higher vaccine effectiveness, higher vaccination pace, increased vaccination coverage, and vaccine prioritisation for an at-risk population. The study findings were restricted to analysis based on the current available data. CONCLUSION: COVID-19 vaccination policies should aim for increased vaccine production as well as a rapid and extensive vaccine delivery system to ensure the maximal value of vaccination strategies. These results can aid policymakers in opting for the most efficient approach to vaccinating the population during this COVID-19 pandemic and future pandemic.

Humoral response to SARS-CoV-2 vaccines among healthcare workers in a tertiary hospital in Malaysia.

INTRODUCTION: Healthcare workers (HCWs) were among the first to be fully vaccinated against SARS-CoV-2. However, the antibody responses to the vaccines and potential decline among Malaysian HCW are still unclear. The objective of this study is to follow-up anti-S antibody levels among HCW vaccinated with mRNA vaccine (BTN162b2) and inactivated vaccine (CoronaVac). MATERIALS AND METHODS: Plasma samples were collected prevaccination, 2 weeks and 6 months post-vaccination and tested for total immunoglobulin levels using ELISA method. RESULTS: A small percentage of HCW (2.2%, 15/677) had elevated anti-S antibody levels in their pre-vaccination plasma samples (median 20.4, IQR 5.8), indicating that they were exposed to SARS-CoV-2 infection prior to vaccination. The mRNA vaccine significantly increased anti-S levels of both previously infected and uninfected individuals to saturation levels (median 21.88, IQR.0.88) at 2 weeks postsecond dose of the vaccine. At 6 months post-vaccination, the antibody levels appeared to be maintained among the recipients of the mRNA vaccine. However, at this time point, anti-S antibody levels were lower in individuals given inactivated vaccine (median 20.39, IQR 7.31, n=28), and interestingly, their antibody levels were similar to anti-S levels in pre-vaccination exposed individuals. Antibody levels were not different between the sexes. CONCLUSION: Anti-S levels differ in individuals given the different vaccines. While further study is required to determine the threshold level for protection against SARSCoV- 2, individuals with low antibody levels may be considered for boosters.