In 2023, there were a total of 58 cases of measles in the United States. Around 72 percent of measles cases that year were attributed to unvaccinated individuals. Meanwhile, those with two doses of vaccination only accounted for just three percent of cases. This statistic shows the number of measles cases reported in the United States from 2020 to 2024, by vaccination status.

There were 285 new cases of measles in the U.S. in 2024. Measles, also known as rubeola, is an infectious disease that is highly contagious and affects mostly children. Common symptoms of measles include fever, runny nose, sore throat, cough, and a rash. Although death rates from measles have decreased around the world, it is still responsible for around 81,000 deaths worldwide per year. Measles vaccination The main reason for the decrease in measles cases and deaths is due to high vaccination rates. The widely used MMR vaccine protects against measles, mumps, and rubella and is safe and effective. In 2023, around 91 percent of adolescents in the U.S. aged 13 to 17 years had received an MMR vaccination. However, in recent years there has been a rise in measles cases in many parts of the world due to vaccine hesitancy. Vaccine hesitancy Vaccine hesitancy refers to a refusal or reluctance to have children vaccinated, despite the overwhelming evidence that vaccines are safe and effective. This hesitancy comes from a misunderstanding of the ingredients in vaccines and how they work, a mistrust of doctors and pharmaceutical companies, and belief in the unfounded associations of vaccines with other diseases and disorders.

In 2024, there were a total of 285 cases of measles in the United States, with 120 of these cases among children aged under five years. From January 1 to April 3, 2025, there were 607 cases of measles. There were also two reported deaths from the disease during this time, the first since 2015. Measles is a highly contagious disease that can be especially dangerous for young children. Vaccines against measles resulted in a significant decrease in cases in the United States over the last few decades; however, increasing vaccine hesitancy and skepticism has been blamed for recent outbreaks.

Project Tycho datasets contain case counts for reported disease conditions for countries around the world. The Project Tycho data curation team extracts these case counts from various reputable sources, typically from national or international health authorities, such as the US Centers for Disease Control or the World Health Organization. These original data sources include both open- and restricted-access sources. For restricted-access sources, the Project Tycho team has obtained permission for redistribution from data contributors. All datasets contain case count data that are identical to counts published in the original source and no counts have been modified in any way by the Project Tycho team. The Project Tycho team has pre-processed datasets by adding new variables, such as standard disease and location identifiers, that improve data interpretabilty. We also formatted the data into a standard data format. Each Project Tycho dataset contains case counts for a specific condition (e.g. measles) and for a specific country (e.g. The United States). Case counts are reported per time interval. In addition to case counts, datsets include information about these counts (attributes), such as the location, age group, subpopulation, diagnostic certainty, place of aquisition, and the source from which we extracted case counts. One dataset can include many series of case count time intervals, such as "US measles cases as reported by CDC", or "US measles cases reported by WHO", or "US measles cases that originated abroad", etc. Depending on the intended use of a dataset, we recommend a few data processing steps before analysis:

Analyze missing data: Project Tycho datasets do not inlcude time intervals for which no case count was reported (for many datasets, time series of case counts are incomplete, due to incompleteness of source documents) and users will need to add time intervals for which no count value is available. Project Tycho datasets do include time intervals for which a case count value of zero was reported. Separate cumulative from non-cumulative time interval series. Case count time series in Project Tycho datasets can be "cumulative" or "fixed-intervals". Cumulative case count time series consist of overlapping case count intervals starting on the same date, but ending on different dates. For example, each interval in a cumulative count time series can start on January 1st, but end on January 7th, 14th, 21st, etc. It is common practice among public health agencies to report cases for cumulative time intervals. Case count series with fixed time intervals consist of mutually exxclusive time intervals that all start and end on different dates and all have identical length (day, week, month, year). Given the different nature of these two types of case count data, we indicated this with an attribute for each count value, named "PartOfCumulativeCountSeries".

In 1970, there were 22.79 new cases of measles per 100,000 population in the United States. However, this rate dropped to .08 in the year 2024. This statistic shows the number of new cases of measles per 100,000 population in the United States from 1919 to 2024.

Project Tycho data include counts of infectious disease cases or deaths per time interval. A count is equivalent to a data point. Project Tycho level 1 data include data counts that have been standardized for a specific, published, analysis. Standardization of level 1 data included representing various types of data counts into a common format and excluding data counts that are not required for the intended analysis. In addition, external data such as population data may have been integrated with disease data to derive rates or for other applications.

Version 1.0.0 of level 1 data includes counts at the state level for smallpox, polio, measles, mumps, rubella, hepatitis A, and whooping cough and at the city level for diphtheria. The time period of data varies per disease somewhere between 1916 and 2011. This version includes cases as well as incidence rates per 100,000 population based on historical population estimates. These data have been used by investigators at the University of Pittsburgh to estimate the impact of vaccination programs in the United States, published in the New England Journal of Medicine: http://www.nejm.org/doi/full/10.1056/NEJMms1215400. See this paper for additional methods and detail about the origin of level 1 version 1.0.0 data.

Level 1 version 1.0.0 data is represented in a CSV file with 7 columns:

• epi_week: a six digit number that represents the year and epidemiological week for which disease cases or deaths were reported (yyyyww)
• state: the two digit postal code state abbreviation that represents the state for which a count has been reported
• loc: the name of a state or city for which a count has been reported, capitalized
• loc_type: the type of location (STATE or CITY) for which a count has been reported
• disease: the disease for which a count has been reported: HEPATITIS A, MEASLES, MUMPS, PERTUSSIS, POLIO, RUBELLA, SMALLPOX, or DIPHTHERIA
• cases: the number of cases reported for the specified disease, epidemiological week, and location
• incidence_per_100000: the number of cases per 100,000 people, computed using historical population counts for cities and states as reported by the US Census Bureau

In the period from January 1, 2023 to June 29, 2025, the week starting March 30, 2025 had the highest number of measles cases, with 114 reported cases. Measles is a highly contagious disease that can be especially dangerous for young children. Vaccines against measles resulted in a significant decrease in cases in the United States over the last few decades; however, increasing vaccine hesitancy and skepticism has been blamed for recent outbreaks.

NNDSS - TABLE 1V. Malaria to Measles, Imported - 2019. In this Table, provisional cases* of notifiable diseases are displayed for United States, U.S. territories, and Non-U.S. residents.

Notice: The total numbers of measles cases in Table 1v for weeks 1-51 in the 2019 data are correct but counts for imported and indigenous categories are incorrect. Measles data for week 52 (in Table 1v) were updated on 02-28-2020 to correct the classification of imported and indigenous. Please see week 52, 2019 data for the correct breakout of imported and indigenous measles cases.

Note: This table contains provisional cases of national notifiable diseases from the National Notifiable Diseases Surveillance System (NNDSS). NNDSS data from the 50 states, New York City, the District of Columbia and the U.S. territories are collated and published weekly on the NNDSS Data and Statistics web page (https://wwwn.cdc.gov/nndss/data-and-statistics.html). Cases reported by state health departments to CDC for weekly publication are provisional because of the time needed to complete case follow-up. Therefore, numbers presented in later weeks may reflect changes made to these counts as additional information becomes available. The national surveillance case definitions used to define a case are available on the NNDSS web site at https://wwwn.cdc.gov/nndss/. Information about the weekly provisional data and guides to interpreting data are available at: https://wwwn.cdc.gov/nndss/infectious-tables.html.

Footnotes: U: Unavailable — The reporting jurisdiction was unable to send the data to CDC or CDC was unable to process the data. -: No reported cases — The reporting jurisdiction did not submit any cases to CDC. N: Not reportable — The disease or condition was not reportable by law, statute, or regulation in the reporting jurisdiction. NN: Not nationally notifiable — This condition was not designated as being nationally notifiable. NP: Nationally notifiable but not published — CDC does not have data because of changes in how conditions are categorized. Cum: Cumulative year-to-date counts. Max: Maximum — Maximum case count during the previous 52 weeks. * Case counts for reporting years 2018 and 2019 are provisional and subject to change. Cases are assigned to the reporting jurisdiction submitting the case to NNDSS, if the case's country of usual residence is the US, a US territory, unknown, or null (i.e. country not reported); otherwise, the case is assigned to the 'Non-US Residents' category. For further information on interpretation of these data, see https://wwwn.cdc.gov/nndss/document/Users_guide_WONDER_tables_cleared_final.pdf. † Previous 52 week maximum and cumulative YTD are determined from periods of time when the condition was reportable in the jurisdiction (i.e., may be less than 52 weeks of data or incomplete YTD data).

§ Measles is considered imported if the disease was acquired outside of the United States and is considered indigenous if the disease was acquired anywhere within the United States or it is not known where the disease was acquired.

NNDSS - TABLE 1V. Malaria to Measles, Indigenous - 2020. In this Table, provisional cases* of notifiable diseases are displayed for United States, U.S. territories, and Non-U.S. residents. Notice: Data from California published in week 29 for years 2019 and 2020 were incomplete when originally published on July 24, 2020. On August 4, 2020, incomplete case counts were replaced with a "U" indicating case counts are not available for specified time period. Notice: Measles data for weeks 1-4 (in Table 1v) were updated on 02-28-2020 to correct the classification of imported and indigenous. For all weeks, measles is considered imported if the disease was acquired outside of the United States and is considered indigenous if the disease was acquired anywhere within the United States or it is not known where the disease was acquired. Note: This table contains provisional cases of national notifiable diseases from the National Notifiable Diseases Surveillance System (NNDSS). NNDSS data from the 50 states, New York City, the District of Columbia and the U.S. territories are collated and published weekly on the NNDSS Data and Statistics web page (https://wwwn.cdc.gov/nndss/data-and-statistics.html). Cases reported by state health departments to CDC for weekly publication are provisional because of the time needed to complete case follow-up. Therefore, numbers presented in later weeks may reflect changes made to these counts as additional information becomes available. The national surveillance case definitions used to define a case are available on the NNDSS web site at https://wwwn.cdc.gov/nndss/. Information about the weekly provisional data and guides to interpreting data are available at: https://wwwn.cdc.gov/nndss/infectious-tables.html. Footnotes: U: Unavailable — The reporting jurisdiction was unable to send the data to CDC or CDC was unable to process the data. -: No reported cases — The reporting jurisdiction did not submit any cases to CDC. N: Not reportable — The disease or condition was not reportable by law, statute, or regulation in the reporting jurisdiction. NN: Not nationally notifiable — This condition was not designated as being nationally notifiable. NP: Nationally notifiable but not published. NC: Not calculated — There is insufficient data available to support the calculation of this statistic. Cum: Cumulative year-to-date counts. Max: Maximum — Maximum case count during the previous 52 weeks. * Case counts for reporting years 2019 and 2020 are provisional and subject to change. Cases are assigned to the reporting jurisdiction submitting the case to NNDSS, if the case's country of usual residence is the U.S., a U.S. territory, unknown, or null (i.e. country not reported); otherwise, the case is assigned to the 'Non-U.S. Residents' category. Country of usual residence is currently not reported by all jurisdictions or for all conditions. For further information on interpretation of these data, see https://wwwn.cdc.gov/nndss/document/Users_guide_WONDER_tables_cleared_final.pdf. †Previous 52 week maximum and cumulative YTD are determined from periods of time when the condition was reportable in the jurisdiction (i.e., may be less than 52 weeks of data or incomplete YTD data). § Measles is considered imported if the disease was acquired outside of the United States and is considered indigenous if the disease was acquired anywhere within the United States or it is not known where the disease was acquired.

Measles Case and Genetic Metadata, Operation Allies Welcome

  Description

The table contains metadata variables used to execute compartmental and genetic modeling on measles cases investigated as a component of Operation Allies Welcome.

  Dataset Details

Publisher: Centers for Disease Control and Prevention Last Modified: 2023-07-28 Contact: Nina Masters (rhv2@cdc.gov)

  Source

Original data can be found at: https://data.cdc.gov/d/b8tp-jsmh

  Usage… See the full description on the dataset page: https://huggingface.co/datasets/HHS-Official/measles-case-and-genetic-metadata-operation-allies.

Once-eliminated vaccine-preventable childhood diseases, such as measles, are resurging across the United States. Understanding the spatio-temporal trends in vaccine exemptions is crucial to targeting public health intervention to increase vaccine uptake and anticipating vulnerable populations as cases surge. However, prior available data on childhood disease vaccination is either on too rough a spatial scale for this spatially-heterogeneous issue, or is only available for small geographic regions, making general conclusions infeasible. Here, we have collated school vaccine exemption data across the United States and provide it at the county-level for all years available. We demonstrate the fine-scale spatial heterogeneity in vaccine exemption levels, and show that many counties may fall below the herd immunity threshold. We also show that vaccine exemptions increase over time in most states, and non-medical exemptions are highly prevalent where allowed. Our dataset also highlights the need for greater data sharing and standardized reporting across the United States.

Methods We collected data from all US states where school vaccine exemption information was freely available from the Department of Health website in any format. We were able to locate that data in 24 states. Within these states, the number of years available varied relatively widely, between 19 years in California and a single year in 6 states. The most represented year in our dataset was 2017 (corresponding to school year 2017-2018). Because the dataset was compiled in June-July 2019, we note that it is possible that additional data for recent years may not be available, or that data may have become available in additional states not included in our dataset.

The data format varied widely between states, and exemptions were reported either as a number of exemptions or as a percentage of the enrolled students. We have elected to use number of students rather than percentages, and have transformed data as needed. For most states included in our dataset, the data are provided at the county level. In several states (Arizona, Colorado, Illinois, Maine, Michigan, South Dakota, Tennessee, Vermont, Oregon, and Washington), the data was provided at the school level, which we aggregated to the county. Additional data processing was necessary in some cases. In Virginia, data was provided by school name, but county or city information was not included. We used a list of public and private schools to match school names with their respective county using fuzzy matching (with the fuzzywuzzy Python package) with an 80\% matching requirement. Our algorithm was unable to find a suitable match for between 3.8\% and 6.8\% of schools (depending on year), and these schools were not included in the final counts at the county level. Similarly, in Idaho, data at the school level included city information but county was not provided. We first matched city and county names, before aggregating the exemption data at the county level. Finally in New York state, exemptions were provided as percentages at the school level but enrollment information was not included. We obtained enrollment for public and private schools separately from the New York State Education Department, and used the school unique code to calculate exemption number from enrollment and exemption percentages. We then aggregated these numbers at the county level.

States reported data for exemptions based on varying definitions, so we selected data records based on data availability to make the data comparable cross states. We aimed to achieve parsimonious definitions of total medical exemptions, total non-medical exemptions, and total exemptions, which includes both types of exemptions. We define medical exemptions as reported total medical exemptions. In Florida, permanent medical exemptions were reported separately from temporary medical exemptions, so permanent medical exemptions was chosen to represent total medical exemptions. To define total non-medical exemptions, we considered the state law regarding non-medical exemptions and the data availability. If the state reported total aggregated non-medical exemptions, that was selected as total non-medical exemptions. If the state reported only religious exemptions and only allows religious exemptions, that was selected as total non-medical exemptions. If the state reported only religious exemptions, but also allows philosophical exemptions, that was considered missing data. If the state allows philosophical exemptions and only reports philosophical exemptions, that was selected as total non-medical exemptions, as the state may not differentiate religious from philosophical. If the state allows philosophical exemptions and reports both religious and philosophical exemptions separately, these values were summed for total non-medical exemptions. To define total exemptions, if the state reported a total exemptions value, this value was used. If the state did not report a total exemptions value, but reported values for total medical exemptions and total non-medical exemptions, as defined above, these were summed for total exemptions. If the state was missing either medical or non-medical exemptions, but reported the total number of students with completed vaccinations, the total exemptions was the difference between the number of students enrolled and the number of students completed.

We also considered disease-specific exemptions reports. If a state reported the number of exemptions for a vaccine specific to a given infection, that value was used. If the state did not report exemptions, but did provide the total number complete for that disease, the difference between the enrolled students and the completed students was used. For pertussis-specific vaccination, we used DTaP exemptions where available, and TDaP exemptions where DTaP was not available. For measles-specific vaccination, if separate reports were available for measles, mumps, and rubella, the value for measles was used. If measles was not available, then the mumps or rubella exemptions were used, if available.

The data in the figures is only data reported for kindergartens in states where kindergarten-specific data was available, or K-12 data in states where kindergarten-specific data was not reported. States reported age groups heterogeneously, and data by other age groups is available in the data file.

In 2023, there were 11 reported cases of measles in Canada, compared to over two thousand cases in 1995. This statistic shows the number of reported cases of measles in Canada from 1930 to 2023.

The global measles vaccine market is a significant sector within the broader pharmaceutical landscape, characterized by substantial growth driven by increasing vaccination campaigns and heightened awareness of the disease's potential severity. The market size in 2025 is estimated at $5 billion, reflecting a robust Compound Annual Growth Rate (CAGR) of approximately 7% from 2019 to 2024. This expansion is fueled by several key factors. Firstly, global initiatives aimed at eradicating measles, spearheaded by organizations like the World Health Organization (WHO), have significantly increased vaccination rates in many developing nations. Secondly, a rising incidence of measles outbreaks in certain regions highlights the persistent threat of the disease and necessitates sustained vaccination efforts. Thirdly, advancements in vaccine technology, leading to improved efficacy and safety profiles, contribute to increased market demand. However, challenges remain. Vaccine hesitancy and misinformation pose significant hurdles to achieving complete measles eradication. Furthermore, logistical constraints, particularly in resource-limited settings, impede effective vaccine distribution and administration. Segmentation within the market is primarily driven by application, with hospitals and clinics representing the largest consumer base. Major players like Novartis, Abbott, Johnson & Johnson, Sanofi, and Merck dominate the market, leveraging their extensive distribution networks and research capabilities. Regional analysis reveals North America and Europe as mature markets with high per capita consumption, while significant growth opportunities exist in Asia-Pacific and other developing regions. The forecast period (2025-2033) anticipates continued growth, albeit potentially at a slightly moderated CAGR, as the global vaccination rate progressively improves, but challenges related to vaccine hesitancy and equitable access remain a factor. The projected market expansion hinges on the continued success of global vaccination initiatives and the ability to overcome existing barriers to access. The market's geographical distribution reflects global health disparities. While developed regions maintain high vaccination coverage, significant investments are required in developing nations to enhance cold-chain infrastructure and public health campaigns. Furthermore, future market dynamics will be shaped by advancements in vaccine technology, potentially leading to multi-dose formulations or novel delivery systems. Competition among pharmaceutical companies will remain intense, driving innovation and pricing strategies. Long-term market success will depend on the strategic partnerships between governments, international organizations, and pharmaceutical companies to guarantee widespread and equitable access to measles vaccines.

Analysis of ‘NNDSS - TABLE 1V. Malaria to Measles, Indigenous’ provided by Analyst-2 (analyst-2.ai), based on source dataset retrieved from https://catalog.data.gov/dataset/05c56409-0de5-4e64-81d3-c82ba82cd092 on 11 February 2022.

--- Dataset description provided by original source is as follows ---

NNDSS - TABLE 1V. Malaria to Measles, Indigenous - 2022. In this Table, provisional cases* of notifiable diseases are displayed for United States, U.S. territories, and Non-U.S. residents.

Notes:

• These are weekly cases of selected infectious national notifiable diseases, from the National Notifiable Diseases Surveillance System (NNDSS). NNDSS data reported by the 50 states, New York City, the District of Columbia, and the U.S. territories are collated and published weekly as numbered tables available at https://www.cdc.gov/nndss/data-statistics/index.html. Cases reported by state health departments to CDC for weekly publication are subject to ongoing revision of information and delayed reporting. Therefore, numbers listed in later weeks may reflect changes made to these counts as additional information becomes available. Case counts in the tables are presented as published each week. See also Guide to Interpreting Provisional and Finalized NNDSS Data at https://www.cdc.gov/nndss/docs/Readers-Guide-WONDER-Tables-20210421-508.pdf. • Notices, errata, and other notes are available in the Notice To Data Users page at https://wonder.cdc.gov/nndss/NTR.html. • The list of national notifiable infectious diseases and conditions and their national surveillance case definitions are available at https://ndc.services.cdc.gov/. This list incorporates the Council of State and Territorial Epidemiologists (CSTE) position statements approved by CSTE for national surveillance.

Footnotes:

*Case counts for reporting years 2021 and 2022 are provisional and subject to change. Cases are assigned to the reporting jurisdiction submitting the case to NNDSS, if the case's country of usual residence is the U.S., a U.S. territory, unknown, or null (i.e. country not reported); otherwise, the case is assigned to the 'Non-U.S. Residents' category. Country of usual residence is currently not reported by all jurisdictions or for all conditions. For further information on interpretation of these data, see https://www.cdc.gov/nndss/docs/Readers-Guide-WONDER-Tables-20210421-508.pdf. †Previous 52 week maximum and cumulative YTD are determined from periods of time when the condition was reportable in the jurisdiction (i.e., may be less than 52 weeks of data or incomplete YTD data). U: Unavailable — The reporting jurisdiction was unable to send the data to CDC or CDC was unable to process the data. -: No reported cases — The reporting jurisdiction did not submit any cases to CDC. N: Not reportable — The disease or condition was not reportable by law, statute, or regulation in the reporting jurisdiction. NN: Not nationally notifiable — This condition was not designated as being nationally notifiable. NP: Nationally notifiable but not published. NC: Not calculated — There is insufficient data available to support the calculation of this statistic. Cum: Cumulative year-to-date counts. Max: Maximum — Maximum case count during the previous 52 weeks.

--- Original source retains full ownership of the source dataset ---

In 2024, there were a total of 285 cases of measles in the United States. Around 89 percent of these cases were among those who were unvaccinated or whose vaccination status was unknown. From January 1 to July 1, 2025, there were 1,267 cases of measles, with those who were unvaccinated or with an unknown vaccination status accounting for 92 percent of these cases. Measles is a highly contagious disease that can be especially dangerous for young children. Vaccines against measles resulted in a significant decrease in cases in the United States over the last few decades; however, increasing vaccine hesitancy and skepticism has been blamed for recent outbreaks.

NNDSS - TABLE 1V. Malaria to Measles, Imported - 2019. In this Table, provisional cases* of notifiable diseases are displayed for United States, U.S. territories, and Non-U.S. residents. Note: This table contains provisional cases of national notifiable diseases from the National Notifiable Diseases Surveillance System (NNDSS). NNDSS data from the 50 states, New York City, the District of Columbia and the U.S. territories are collated and published weekly on the NNDSS Data and Statistics web page (https://wwwn.cdc.gov/nndss/data-and-statistics.html). Cases reported by state health departments to CDC for weekly publication are provisional because of the time needed to complete case follow-up. Therefore, numbers presented in later weeks may reflect changes made to these counts as additional information becomes available. The national surveillance case definitions used to define a case are available on the NNDSS web site at https://wwwn.cdc.gov/nndss/. Information about the weekly provisional data and guides to interpreting data are available at: https://wwwn.cdc.gov/nndss/infectious-tables.html. Footnotes: U: Unavailable — The reporting jurisdiction was unable to send the data to CDC or CDC was unable to process the data. -: No reported cases — The reporting jurisdiction did not submit any cases to CDC. N: Not reportable — The disease or condition was not reportable by law, statute, or regulation in the reporting jurisdiction. NN: Not nationally notifiable — This condition was not designated as being nationally notifiable. NP: Nationally notifiable but not published — CDC does not have data because of changes in how conditions are categorized. Cum: Cumulative year-to-date counts. Max: Maximum — Maximum case count during the previous 52 weeks. * Case counts for reporting years 2018 and 2019 are provisional and subject to change. Cases are assigned to the reporting jurisdiction submitting the case to NNDSS, if the case's country of usual residence is the US, a US territory, unknown, or null (i.e. country not reported); otherwise, the case is assigned to the 'Non-US Residents' category. For further information on interpretation of these data, see https://wwwn.cdc.gov/nndss/document/Users_guide_WONDER_tables_cleared_final.pdf. † Previous 52 week maximum and cumulative YTD are determined from periods of time when the condition was reportable in the jurisdiction (i.e., may be less than 52 weeks of data or incomplete YTD data).

Although there has been an overall decline in a number of vaccine-preventable diseases in the U.S., the number of pertussis cases has increased since 1980. This statistic shows the number of reported cases of select vaccine-preventable diseases in the U.S. from 1980 to 2022.

In 2024, there were a total of 285 cases of measles in the United States. That year, around half of measles cases among children aged under five years were hospitalized for isolation or for management of measles complications. From January 1 to July 1, 2025, there were 1,267 cases of measles, with 21 percent of cases among children under five needing hospitalization. Measles is a highly contagious disease that can be especially dangerous for young children. Vaccines against measles resulted in a significant decrease in cases in the United States over the last few decades; however, increasing vaccine hesitancy and skepticism has been blamed for recent outbreaks.

Rank, number of deaths, percentage of deaths, and age-specific mortality rates for the leading causes of death, by age group and sex, 2000 to most recent year.

The layout is analogous to Table 1. Although the ‘None’ model, has a within two (i.e. our chosen threshold for statistical significance) of the best model, our analysis still suggests that is statistically different for the United States and Canada, because both of these models have distinct values for the two countries. Thus the model (bold cell) is our preferred model. There were a total of 336 cases in the United States among 166 chains and a total of 274 cases in Canada among 49 chains.Inference results for comparing the transmissibility of measles in the United States (1997–1999) and Canada (1998–2001).