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

Definition of immunize

transitive verb

: to make (someone or something) immune to something : to provide with protection against or immunity from something … the investigation has been slowed by the refusal of seven former and current Hughes officials to cooperate unless immunized from prosecution.— Andy Pasztor and Rick Wartzman Budding novelists immunize themselves against rejection by recalling rebuffs endured by even the most successful novelists …— Edwin McDowell specifically : to make (a living organism) immune or resistant to a disease or pathogenic agent especially by inoculation : to create immunity in (as with a vaccine) Measles can be almost completely controlled when adequate numbers of people within a population are immunized. Scientific American Medicine immunizing as many citizens as possible before an outbreak makes sense … — Shannon Brownlee

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Examples of immunize in a Sentence

Many people had to be immunized after being exposed to the disease.
Recent Examples on the Web The Health Ministry embarked on a vaccination campaign in late November 2018 and, within five days, immunized more than 17,000 people. Anchorage Daily News, "Deadly measles outbreak hits children in Samoa after anti-vaccine fears," 27 Nov. 2019 Women who have been infected by or immunized against measles pass the protection their immune systems develop — known as maternal antibodies — to their fetuses during pregnancy. Helen Branswell, STAT, "Measles immunity passed from mother to baby may erode quicker than believed, study says," 21 Nov. 2019 Roughly 90% of those not immunized against measles contract the disease seven to 21 days after exposure, according to the LA County Health Department. Scott Craven, azcentral, "Disneyland visitors may have been exposed to measles," 23 Oct. 2019 These recent outbreaks have been put down to the growth of the anti-vaccination movement, which has spread via social media and discourages parents from immunizing their children against measles and other diseases. Jessie Yeung, CNN, "Measles wipe immune system's memory of other illnesses, studies find," 1 Nov. 2019 But the results are another good reason to immunize children against the virus, the studies' authors and other infectious disease experts say. Eva Frederick, Science | AAAS, "How measles causes the body to ‘forget’ past infections by other microbes," 31 Oct. 2019 Ethan Lindenberger, 18, who had never been vaccinated, had begun to question his parents’ decision not to immunize him. Robert Mckeever, Quartz, "How pro-vaccine parents can help stop the rise of the anti-vaxxer movement," 8 Oct. 2019 The law is already encouraging parents on the fence about vaccination to immunize their children, and is sending a message to public and private schools that the days of selective vaccination are over. Sharon Otterman, New York Times, "Get Vaccinated or Leave School: 26,000 N.Y. Children Face a Choice," 3 Sep. 2019 According to the Oregon Department of Education, 96% of Grant High students have been immunized for pertussis. oregonlive, "Case of whooping cough confirmed at Grant High School," 31 Oct. 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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Time Traveler for immunize

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The first known use of immunize was in 1889

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Last Updated

10 Dec 2019

Cite this Entry

“Immunize.” The Dictionary, Merriam-Webster Inc., Accessed 13 December 2019.

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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


How to pronounce immunize (audio)

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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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
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

Comments on immunize

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easily led, controlled, or managed

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