#  From Moon Shot to Arm Shot: The Story of the Measles Vaccine 

 





In downtown Boston, you can walk the Freedom Trail and witness the sites that led to the birth of a revolution and a country. In the Boston Commons, you can walk the many well-tended paths of America’s oldest public park. And here in Longwood, the central hub of the Virology Ph.D. program, you can walk the busy sidewalks in front of Boston Children’s Hospital, the birthplace of the measles vaccine.



 

August 31, 2026

 

 

 [ Ashley Tseng ](/people/ashley-tseng) 

Measles is a highly infectious childhood disease caused by the measles virus (MeV). Symptoms include [fever, cough, and the infamous blotchy red rash](https://www.ncbi.nlm.nih.gov/books/NBK448068/). The cough is doubly dangerous, as it can transmit the virus through respiratory droplets where the virus can remain viable in the air or on surfaces for several hours. Measles is so contagious that one symptomatic patient can [infect up to 12-18 people](https://www.who.int/news-room/fact-sheets/detail/measles). Once a childhood scourge, measles was finally brought to heel in 1963 by the release of a live-attenuated vaccine thanks to the untiring efforts of multiple scientists, including Dr. Thomas Peebles and Dr. John Enders.

A live-attenuated vaccine is a type of vaccine that introduces a weakened version of the pathogen, like measles, to your immune system. This allows your immune system to recognize the pathogen, fight it off, and develop a memory without severe complications. If you encounter the actual virus in future infections, your immune response is primed to react much quicker. But what does it take to wrangle a highly infectious agent into a harmless shadow of itself?

The first hurdle facing scientists was the question of growing measles in a lab. How can one even begin to study measles if there is no simple, systematic way to culture it? In [a landmark paper](https://pubmed.ncbi.nlm.nih.gov/13177653/) published in 1954, Drs. Peebles and Enders demonstrated that, after infecting human and monkey cell cultures with blood or throat washes from measles patients, they could isolate the virus. In human kidney cells, the authors observed what virologists call a *cytopathic effect*, a phenomenon where cells are abnormally enlarged, become rounder, and even fuse with neighboring cells. Now that scientists could grow the virus, how would they weaken it? To do so, the scientists used a technique called serial passaging.

[Serially passaging](https://pdf.sciencedirectassets.com/314764/3-s2.0-C20130069216/3-s2.0-B9780128009468000040/main.pdf?X-Amz-Security-Token=IQoJb3JpZ2luX2VjEEQaCXVzLWVhc3QtMSJHMEUCIC3X41DHop5VGBkOMpTdtOAKvmXs38mvI%2BsOKlTxgBJoAiEApUfBeG3E9kzHxQ0Iru6A3ZlZEY%2Fyz3PM98Zp3nvdhx8qsgUIDRAFGgwwNTkwMDM1NDY4NjUiDHTQ7LcjSsFOWxC62SqPBTFZ%2F5gnEWMB%2FbG%2BKbtvgT2JgdLZ9fTC8R58GruNvE7HVp21gkQGOzGFi9W%2B0DWRFQhW%2FAw%2FujwzQGamjobUOQmpRwL5JrVcXl6zZ9xxkW1F189DGgK3p%2F2zVSwmoAB0FoiFsLIap4DDAxqntca4fRzX%2BwcwA8BHgZVGoKMjCq9s8g8WSJ7wUPt%2BFYQKF9VrZjgi5bP84OswdvR34w5Pda%2Bothyh4X78XzDjGrzNeoot2OP38Hkj0naWDqQpkRzx3onjpVpvGdzG6RBwAGFz70CuRsV2HjwYNmpkBRIUFNjvwQ7nFhnbRl6IeBFg2ln6a%2F%2FG8dhBVSuCBfs%2BlB4yxNW1WawxL6ngARv8kIVqmZavsZfp4ef9pAJ%2BQhCOHu7leW8Mq5nqHIkMGDrsdgcHeEyanu6L6Sxi3oNufZv8ql2WiVepzOw40xfI1zrcwXkuR9tpDgwtx%2FnvLb501zBNJiekUyuI1usu%2Fc6eSGpru5vdnUijfK5prEasvhdUgTGAJY0q6nA5dJcuxxhsJYWIS3EjIutqWCy4ueRfCWv11qztLRFEu6Wz8GlCusSOhn4q2r97%2BvbTwJ%2Br4l4tdpKyRTHagDa27bft9puFg3LgIOEPUzmtjsdHbZnu%2BipWccxCI38bPinDp0xSfN7wSwV9TORdVRjwR72vO6Y0%2BBlddI1ygcIIW02TetrYLrIpynNsa7KBS80bj3TqKG%2B5RGX98JbB4d8AUcUL5H9Zrfy%2FK9oQxW70tvEAbdcNm%2BtrKx7zhtaOz8MLddyscEAg0sWO0XpiWtwj2pEfoGxXnLOIk%2BHCbOx2BTc1p%2B3xpdKmbsko0E2PrdUr5bYaktRzS57%2FO8PotmUpZL5wEQmxIFNzdfwwpv%2BO0wY6sQEAFIttzjKoWLQOMwa2ygnsh5F0%2FQHxJofSU5AfdMBrwNx9J2OoHswemZQ8FG%2BDGbhDmYPYZVG6mXqtPLymvXfTF0e1lkH1DE9Z0h8owduNUv3NlNyVWj9jwpN6ftGEfOA%2F4t9OA6e6SV%2FgYlSvv7gxhj05MhAcDDjJ7LtQlTRqE9XxIjj9VLEp%2FbdrnAqo0WdXTirIXsdIx8DAgpadvK3gz663mUR1N2QQA26VA9xmkeA%3D&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260724T203103Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=ASIAQ3PHCVTYUR4XHCR7%2F20260724%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=f2543c2877a83e33ff7a980f4b164338883f65ff1dcfa927102539c215be7c52&hash=315732f5e68e408166c3190e006fe0252e3ae40db3249337cfdcffd1a1080498&host=68042c943591013ac2b2430a89b270f6af2c76d8dfd086a07176afe7c76c2c61&pii=B9780128009468000040&tid=spdf-ed839117-2d70-493b-9fb8-c12fef9516e7&sid=d4ef2860724e464dd65815d13fe6c14ab1cdgxrqa&type=client&tsoh=d3d3LnNjaWVuY2VkaXJlY3QuY29t&rh=d3d3LnNj) a virus is like driving the natural selection of viruses. First, the virus is grown on a population of cells, say human kidney cells, and then isolated. The isolated virus is plated on a fresh set of human kidney cells again. We call this a passage, and it is repeated multiple times. Each time the virus replicates, there is the possibility that mutations arise that can alter pathogenicity, virulence, or infectivity. Over successive passages, virus variants that replicate most efficiently under laboratory conditions are enriched.

The next step is to take the adapted virus and move it into increasingly different cell types and serially passage the virus again. The new cell types may come from a different tissue or species. By introducing the virus into a new environment, it can select for mutations that allow the virus to survive. However, by adapting to the new environment, the virus can become less fit in its original environment. This is known as attenuation of a virus for vaccine purposes. The ultimate goal of a live attenuated vaccine is a high-wire act in which the virus must still be able to replicate and induce a protective immune response, but weak enough to not elicit severe illness.

The measles virus was serially passaged [through human kidney cells, human amnion cells, and finally chicken embryo cells](https://pmc.ncbi.nlm.nih.gov/articles/PMC1522581/?page=1). In [multiple studies](https://www.nejm.org/doi/10.1056/NEJM196007282630408) in monkeys and later children, vaccinated patients did not develop severe disease. The final test was to determine the presence of protective antibodies, Y-shaped molecules that can prevent the MeV from infecting human cells, an indication of immune memory. Sera from vaccinated patients were collected and mixed with MeV, and the mixture plated onto cells susceptible to the virus. If the cells stayed alive, an effective immune response had been mounted. With protective antibodies detected and successful trials, the Edmonston B measles vaccine, named after the boy the original virus was isolated from, was licensed for use in 1963. Today, some measles, mumps, rubella (MMR) vaccines still use [a modified version of the Edmonston B strain](https://www.chop.edu/vaccine-update-healthcare-professionals/newsletter/what-should-i-know-about-new-mmr-vaccine-priorix) of measles.

 ![Measles Vaccine](/sites/g/files/omnuum5516/files/2026-08/Ashley_Tseng_SciComm.jpg)

 

Figure 1| Measles was first isolated from a sick patient and then serially passaged on human kidney cells. It was then moved to different cell types to attenuate it. The final product is a live-attenuated vaccine. *Image credit: Ankita Chopde.*

While serially passaging a virus can lead to the development of a successful vaccine, it is a laborious process that also makes it difficult to elucidate the role of each mutation in the virus. Multiple viral proteins may have multiple changes. This makes it challenging to pinpoint the specific molecular mechanisms that have been handicapped, details that would be useful for the development of future therapeutics. Today, across Harvard and in the Virology Ph.D. program, many labs are performing cutting-edge research on vaccine development using the [rational design](https://pmc.ncbi.nlm.nih.gov/articles/PMC7108399/) philosophy. Decisions about everything from antigen selection to the delivery method are intentionally designed and informed by a combination of structural work, immunology, and virology rather than a process of trial and error.

Today, the measles vaccine has re-entered the spotlight. In 2026 alone, there have been [2,318 confirmed cases of measles](https://www.nytimes.com/2026/07/24/well/measles-record-united-states-numbers.html?smid=url-share), a major public health setback for a disease that was declared eliminated in the US in 2000. The number of cases this year have already smashed last year’s record of 2,289 cases. The US’ elimination status, [a distinction where measles transmission has been interrupted for 12 months or more](https://www.kff.org/other-health/measles-elimination-status-what-it-is-and-how-the-u-s-could-lose-it/), is up for review by an international board in November.

The resurgence of the disease has been [traced to a national pullback](https://pmc.ncbi.nlm.nih.gov/articles/PMC9037455/) from measles vaccination. The national *average* vaccination rate hovers at around 93%, a touch below the [recommended 95% rate](https://www.immunizationagenda2030.org/images/documents/measles_rubella_initiative_Digital3.pdf) to limit transmission. However, in pockets around the country, vaccination rates can dip far lower, allowing the virus to gain a foothold and spread. The Centers for Disease Control (CDC) has reported [35 measles outbreaks](https://www.cdc.gov/measles/data-research/index.html) alone this year. The US is now on the back foot in its fight against an old and familiar enemy. However, that does not diminish the success that is the measles vaccine. Rather, it is a testament to the power and ingenuity of the American research enterprise. The measles vaccine is proof that a persistent disease has met its match in even more persistent scientists.

*Interested in following the recent measles outbreaks? You can track local cases with the* [*Measles Tracker*](https://publichealth.jhu.edu/ivac/resources/us-measles-tracker) *from John Hopkins to stay updated.*



 

 

 



 

 See also:- [ Viruses in Focus ](/blog-topic/viruses-focus)
 
 

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