Bhutan’s experience with COVID-19 vaccination in 2021

Herd immunity is a key concept for epidemic control. It states that only a proportion of a population needs to be immune (through overcoming natural infection or through vaccination) to an infectious agent for it to stop generating large outbreaks. A key question in the current COVID-19 pandemic is how and when herd immunity can be achieved and at what cost.

Abstract Background Global vaccine development efforts have been accelerated in response to the devastating COVID-19 pandemic. We evaluated the impact of a 2-dose COVID-19 vaccination campaign on reducing incidence, hospitalizations, and deaths in the United States (US). Methods We developed an agent-based model of SARS-CoV-2 transmission and parameterized it with US demographics and age-specific COVID-19 outcomes. Healthcare workers and high-risk individuals were prioritized for vaccination, while children under 18 years of age were not vaccinated. We considered a vaccine efficacy of 95% against disease following 2 doses administered 21 days apart achieving 40% vaccine coverage of the overall population within 284 days. We varied vaccine efficacy against infection, and specified 10% pre-existing population immunity for the base-case scenario. The model was calibrated to an effective reproduction number of 1.2, accounting for current non-pharmaceutical interventions in the US. Results Vaccination reduced the overall attack rate to 4.6% (95% CrI: 4.3% - 5.0%) from 9.0% (95% CrI: 8.4% - 9.4%) without vaccination, over 300 days. The highest relative reduction (54-62%) was observed among individuals aged 65 and older. Vaccination markedly reduced adverse outcomes, with non-ICU hospitalizations, ICU hospitalizations, and deaths decreasing by 63.5% (95% CrI: 60.3% - 66.7%), 65.6% (95% CrI: 62.2% - 68.6%), and 69.3% (95% CrI: 65.5% - 73.1%), respectively, across the same period. Conclusions Our results indicate that vaccination can have a substantial impact on mitigating COVID-19 outbreaks, even with limited protection against infection. However, continued compliance with non-pharmaceutical interventions is essential to achieve this impact.

Background The proportion of incident cases of HPV-attributable cancers is highest in the low- and middle-income countries (LMICs) but many are yet to initiate HPV vaccination programs. This meta-analysis was performed to assess the uptake of HPV vaccination in LMICs at the beginning of the global strategy to eliminate cervical cancer and describes the gaps and challenges. Methods A systematic search was conducted in PubMed, EMBASE, Scopus, Web of Science, and CENTRAL databases for observational studies that reported the uptake of HPV vaccination until October 2020. The meta-analysis was done using a random-effects model to assess the pooled estimate of HPV uptake. CRD42021218429 Findings During 2008–2020, an estimated 3.3 million females received at least one dose of HPV vaccine with 61.69% of the target population vaccinated. In countries with high uptake, the pooled estimate of uptake was higher in females than males (45.48% vs 8.45%) and showed significant decline in 2015–2020 compared to 2006–2014 (89.03% vs 41.48%). In countries with low uptake, the estimate of uptake was low in both males and females (5.31% vs 2.93%) and showed increase in uptake in 2015–2020 compared to 2006–2014 (0.76% vs 5.22%). In countries with high uptake, compared to routine programs, the estimate was higher when delivered through demonstration programs (89.94% vs 59.74%). Interpretation The major concern was a significant drop in the uptake in countries that started with high uptake, challenges in the maintenance of vaccine uptake, sustainability of funding and the lack of standard monitoring and reporting.