# Immunization coverage and registries

Learn how Canada tracks immunization against vaccine-preventable diseases. Also find out what we are doing to improve immunization registries and databases.

## About immunization coverage

Certain vaccinations are recommended for babies, children and adults in Canada.  These vaccinations are listed in immunization schedules that are recommended by experts in Canada. When people are immunized according to their proper schedule, they are considered to be protected from that disease.

We measure this vaccine uptake (or coverage) to know how protected the population is against a vaccine-preventable disease. If coverage is high, it is less likely that the diseases will spread.

In Canada, immunization coverage is estimated by conducting coverage surveys. These surveys provide information about the percentage of people who are properly immunized against particular diseases. They can also detect coverage patterns over time.

If we know the levels of vaccine coverage in Canada, we can:

• learn more about Canadians who may be vulnerable to diseases because they are:
• under-immunized
• not immunized at all
• design immunization programs to give Canadians accurate information so they can make informed choices

The coverage estimates are measured by:

1. calculating the number of people who actually received a certain vaccine
2. comparing that to the number of people who should have received that vaccine

For example, measles immunization coverage can be measured as follows:

$\frac{\mathrm{Number}\phantom{\rule{0.5em}{0ex}}\mathrm{of}\phantom{\rule{0.5em}{0ex}}\mathrm{children}\phantom{\rule{0.5em}{0ex}}\mathrm{receiving}\phantom{\rule{0.5em}{0ex}}2\phantom{\rule{0.5em}{0ex}}\mathrm{doses}\phantom{\rule{0.5em}{0ex}}\mathrm{of}\phantom{\rule{0.5em}{0ex}}\mathrm{measles}\phantom{\rule{0.5em}{0ex}}\mathrm{vaccine}\phantom{\rule{0.5em}{0ex}}\mathrm{before}\phantom{\rule{0.5em}{0ex}}\mathrm{age}\phantom{\rule{0.5em}{0ex}}7}{\phantom{\rule{0.5em}{0ex}}}×100%$

The math formula describes how immunization coverage is calculated in a population. The numerator is the number of children receiving 2 doses of measles vaccine before age 7. The denominator is the total population of children under age 7. The calculation is the numerator divided by the denominator, and then multiplied by 100.

## National immunization coverage surveys

Canada's national immunization coverage surveys estimate vaccination coverage. The surveys also assess Canadians' knowledge, attitudes and behaviours about immunization. These surveys are conducted approximately every 2 years. They measure and record the immunization coverage of certain vaccines in:

• children aged 2, 7 and 17
• adults aged 18 and over

In Canada, the National Advisory Committee on Immunization (NACI) recommends vaccines based on their safety, effectiveness and benefits. Provinces and territories create vaccine programs based on local information. This information includes:

• who gets the disease
• at what age they get the disease
• how common the disease is
• severity of the illness

These factors can change depending on location. For this reason, there are differences across Canada on when vaccines are given. These differences are covered by the provincial and territorial immunization schedules.

The immunization schedules for all publicly funded vaccines in the provinces and territories are available for public viewing. The national immunization coverage surveys include all vaccines that are part of the NACI recommended schedules.

The results from the national immunization coverage surveys are helpful but have some limitations, such as:

• low response rate
• bias
• this happens when survey participants do not accurately represent all Canadians, including certain people, like:
• First Nations
• adults in institutions, such as nursing homes and prisons
• newcomers to Canada
• those who are not fluent enough in English or French to be interviewed in either official language
• inaccurate self-reporting or self-monitoring of immunization history, which is usually because:
• immunization cards or booklets have been lost for children
• adult memory is not as exact or as complete as a medical record

Immunization coverage estimates will continue based on surveys until automated systems for record-keeping are in place across Canada.

## National network of immunization registries

Provinces and territories are currently working towards the development of a national network of immunization registries. Each province and territory maintains its own system for tracking immunization coverage.

In most provinces and territories, immunization data is collected mainly on children.

How provinces and territories record childhood immunization data may be different. Some jurisdictions have electronic databases to track childhood immunization data, while others use paper-based systems. Some use a combination of both.

There are also differences between jurisdictions regarding the type of data being collected.

Electronic registries in Canada will be used to improve immunization monitoring. They will be used to:

• identify children who are due or overdue for immunization
• provide health care providers with the patient's immunization status at each visit
• identify populations at risk for not getting immunized on time so that public health campaigns can reach these people
• evaluate immunization coverage and help assess programs

Most provinces and territories are working towards electronic immunization registries.

## Bar coding vaccine products in Canada

Bar coding vaccine products is how Canada automates vaccine identification. It improves the accuracy of recording vaccine data into an electronic system.

The bar code on a vaccine product contains all of the important information about a vaccine product. The bar code allows the vaccine data to be scanned into an electronic immunization record. This reduces record-keeping errors and ensures the patient's record is complete.

In Canada, millions of vaccine doses are given every year. A health care provider must record details every time a patient receives a dose of vaccine. This information goes in a patient's paper-based health record or in an electronic system or registry.

## Vaccine Information Database System

The Vaccine Identification Database System (VIDS) is an online database of current information on vaccines licensed for use in Canada. VIDS is the link between the vaccine's bar code and the information needed to automatically fill in patient records. The database is provided free of charge to all Canadian health care providers. Immunization registries can link directly to VIDS for up-to-date information on vaccines in Canada.