im·​mu·​nize | \ ˈi-myə-ˌnīz How to pronounce immunize (audio) \
immunized; immunizing

Definition of immunize

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Other Words from immunize

immunization \ ˌi-​myə-​nə-​ˈzā-​shən How to pronounce immunization (audio) also  i-​ˌmyü-​nə-​ \ noun

Examples of immunize in a Sentence

Many people had to be immunized after being exposed to the disease.

Recent Examples on the Web

California’s kindergarten vaccination rate dropped again in the most recent school year as more parents sought permission from doctors to not immunize their children, according to new state data. Julia Wick,, "Essential California: The war on smog is stalling after decades of improvement," 2 July 2019 This effort aims to immunize case contacts and contacts-of-contacts to try to strategically thwart the spread of the disease. Beth Mole, Ars Technica, "Ebola spreads in Uganda, but not an international emergency, WHO says [Updated]," 14 June 2019 About two-thirds of Ohio children between the ages of 18 months and 3 years are immunized, putting Ohio's immunization rate at No. 45. Jackie Borchardt,, "Not vaccinated? A new Ohio bill could prevent you from being fired for refusing immunizations," 14 June 2019 Who Got Measles as an Adult, Advocates for Parents to Vaccinate Their Kids California passed a bill in 2015 that requires school children to be immunized against 10 different diseases, including measles. Ashley Boucher,, "New York Eliminates Religious Exemptions for Vaccinations Despite Protests from Anti-Vaxxer Groups," 13 June 2019 The father of another child who has not been immunized believes that big pharmaceutical companies are paying millions of dollars to doctors, government officials and even judges to bury the truth about vaccine complications. New York Times, "Bastion of Anti-Vaccine Fervor: Progressive Waldorf Schools," 13 June 2019 The bill calls on the state department of public health to review exemptions by doctors who give five or more medical exemptions per year, or for children in schools where less than 95% of students are immunized. Alejandro Lazo, WSJ, "Bill to Limit Vaccine Exemptions in California Draws Protests," 20 June 2019 The government tries to make the program’s existence known by printing its phone number and website on the vaccine information statements that doctors are required to give patients when they are immunized. New York Times, "Vaccine Injury Claims Are Few and Far Between," 18 June 2019 When enough of a community is immunized against a disease, that group has what's known as herd immunity, meaning there is a low risk of a disease spreading. Elizabeth Byrne, Shiying Cheng, Houston Chronicle, "Texas vaccine exemption rates have reached an all-time high. Did Texas make it too easy for parents," 12 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'immunize.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of immunize

1889, in the meaning defined above

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Statistics for immunize

Last Updated

9 Jul 2019

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Time Traveler for immunize

The first known use of immunize was in 1889

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More Definitions for immunize



Financial Definition of immunization

What It Is

Immunization is a dedicated-portfolio strategy used to manage a portfolio with the goal of making it worth a specific amount at a certain point, usually to fund a future liability. Immunization is one of two kinds of dedicated-portfolio strategies (cash-flow matching is the other).

How It Works

To understand the immunization strategy, first remember that although bond prices fall when interest rates rise, the rate at which the investor can reinvest his coupon payments increases (the opposite is also true: when rates fall, prices rise but the reinvestment rate falls). For example, let’s assume an investor purchases a $10,000 bond at par. The bond has a 10% coupon paid semiannually and matures in three years. If market yields stay at 10%, the following would occur at the end of the first two years:

As the table shows, the investor would receive $2,000 in coupon payments, which he would reinvest as he receives them at the market rate of 10% per year, earning him another $155. When the coupons and the interest on interest are added to the bond principal, the accumulated value of his investment is $12,155, for a 10% annual return.

Now consider what happens if market yields increase, say to 15%, right after the investor purchases the bond.

The higher reinvestment rate increased the amount of interest the investor earned on the coupon payments. However, the price of the bond fell more than enough to offset this gain. The net result was a decrease in total return. Now compare this to what would have happened if reinvestment rates fell to 8% instead.

In this example, the low reinvestment rate reduced the interest earned on the coupon payments. But the bond price rose, offsetting some of this loss. The net result was an increase in total return. Thus, the yin-yang relationship between interest rates and bond prices also creates a tradeoff between reinvestment risk and interest rate risk.

The trick to immunization therefore is to find bonds where the change in interest on interest exactly offsets the change in price when rates change. This can be done by setting the duration of the portfolio equal to the investor’s time horizon and making sure the initial present value of the bond equals the present value of the liability in question. In our previous example, we assumed the investor intended to hold the bond for two years, presumably because he intends to use the money to fund some obligation. Thus, to immunize the portfolio, the investor should set the duration to two years. Six months later, the investment horizon will be 1.5 years, and the investor should rebalance the portfolio’s duration to equal 1.5 years, and so on. The intended result: an income portfolio that has an assured return for a specific time horizon regardless of changes in interest rates.

Why It Matters

A dedicated-portfolio strategy, and immunization in particular, is most appropriate when an investor needs to fund a future liability. When executed well, it can provide terrific returns (and tremendous peace of mind) to investors. But immunization is not without risks. It requires investors to calculate and time future liabilities, which isn’t always easy or accurate. Immunization also assumes that when interest rates change, they change by the same amount for all types of bond maturities (this is called a parallel shift in the yield curve). This, of course, rarely happens in the real world and it therefore makes duration matching more difficult. Thus, the immunization strategy does not ensure the expected return when interest rates change (this deviance is called immunization risk).

One way to control immunization risk is to invest solely in zero-coupon bonds that have maturities matching the investor’s time horizon. Portfolios with high immunization risk, on the other hand, include high-coupon securities that mature at regularly spaced intervals over the course of the portfolio’s time horizon (this is called laddering). This constant maturing means frequent reinvestment, which means a high sensitivity to changes in interest rates and thus high immunization risk.

Source: Investing Answers



English Language Learners Definition of immunize

: to give (someone) a vaccine to prevent infection by a disease


im·​mu·​nize | \ ˈi-myə-ˌnīz How to pronounce immunize (audio) \
immunized; immunizing

Kids Definition of immunize

: to make immune especially by vaccination

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transitive verb
variants: also British immunise \ ˈim-​yə-​ˌnīz How to pronounce immunise (audio) \
immunized also British immunised; immunizing also British immunising

Medical Definition of immunize

: to make immune


transitive verb
im·​mu·​nize | \ ˈi-myə-ˌnīz How to pronounce immunize (audio) \
immunized; immunizing

Legal Definition of immunize

: to grant immunity to the ultimately ill-fated effort to immunize state judges from the burdens of the federal income tax— J. K. Owens

Other Words from immunize

immunization \ ˌi-​myə-​nə-​ˈzā-​shən How to pronounce immunization (audio) \ noun

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More from Merriam-Webster on immunize

Rhyming Dictionary: Words that rhyme with immunize

Spanish Central: Translation of immunize

Nglish: Translation of immunize for Spanish Speakers

Britannica English: Translation of immunize for Arabic Speakers

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