National Passive Surveillance
Regular reporting of disease data by all institutions that see patients (or test specimens) and are part of a reporting network is called passive surveillance. There is no active search for cases. It involves passive notification by surveillance sites and reports are generated and sent by local staff.
A passive surveillance system relies on the cooperation of health-care providers — laboratories, hospitals, health facilities and private practitioners — to report the occurrence of a vaccine-preventable disease to a higher administrative level. Once the data have been received, they must be compiled and then analysed to monitor disease patterns and identify possible outbreaks. Passive surveillance involves the regular collection and reporting of surveillance data and is the commonest method used to detect vaccine-preventable diseases. In most countries with a passive surveillance system, every health facility is required to send a monthly (sometimes weekly/daily) report of all cases of vaccine-preventable disease (and sometimes other diseases of interest) on a standard form.
Passive surveillance is less expensive than other surveillance strategies and covers wide areas (whole countries or provinces); however, because it relies on an extensive network of health workers, it can be difficult to ensure completeness and timeliness of data.
Some countries might not have the capacity or resources to identify all cases of a disease, either because the diagnosis of the disease requires specialized clinical skills or because laboratory resources are not available throughout the country. Under these circumstances, passive surveillance can be adapted in a number of ways, depending on the completeness and quality of data required, financial constraints and the availability of specialist skills and services.