1.) Which single design limitation most threatens valid estimates of sensitivity and representativeness? How would you address it within six weeks?
The main limitation was reliance on passive, facility-based reporting with incomplete facility coverage and under-participation, which makes the system insensitive and non-representative.
To improve this limitation within 6 weeks, producing reporting at sentinel sites may be required. The plan could be addressed as follows:
– Preparation and training: preparation of tools (simple and feasible for usage) and training personnel with training material to understand and have an insight for surveillance.
– Surveillance: prospective active finding at sentinel and community with daily reporting of any AEFI and weekly home-based checks for a sample of recently vaccinated children/adults. Ensuring private facilities in each sentinel are enrolled as reporting sites and asked to send daily/weekly counts.
– Data cleaning & rapid capture–recapture estimate: producing a short report with estimated sensitivity and representativeness gaps and recommended scale-up.
– Feedback and adjustment: sharing results and using findings to expand the sentinel approach to more sentinels; immediately include private providers into routine reporting; update local communication to caregivers to report AEFI.
2.) Using the CDC surveillance attributes, propose one low-cost intervention to increase sensitivity. State the expected trade-offs, and list 2–3 indicators to detect impact from the intervention.
Intervention:
– Targeted sentinel active surveillance using rapid reporting with SMS or simple application (e.g. WhatsApp, LINE) for daily check-in from a selected network of sentinel. Uses existing tools requires only modest spending, brief training, and simple line lists. This makes reporting active rather than only passive, captures minor events that otherwise are not reported, and ensures private clinics and rural communities are included at sentinel level.
Expected trade-offs / downsides:
– More false positives: broad catching will raise reports of events unrelated to vaccination (lower specificity and more investigations).
– Increased workload for triage/investigation — could overwhelm limited investigation capacity.
– Short-term resource needs: budgets, airtime, and coordination time.
Indicators to detect impact
– AEFI reporting rate and proportion should rise if sensitivity improves and shows engagement/coverage increase.
– Completeness of key fields on AEFI line lists improved data quality suggests usable additional sensitivity.
3.) For a newly introduced vaccine, should the AEFI case definition be temporarily broadened to maximize early signal detection?
Yes — A broader case definition (more sensitive, less specific) increases the chance of detecting rare or unexpected early safety signals during rollout that critical when background safety profiles are uncertain.
