An Analysis in Measles Outbreak of 2014: The Role of Personal Beliefs Exemptions.

FELIX SHIH

GEOGRAPHY490

CALIFORNIA STATE UNIVERSITY, NORTHRIDGE

DEPARTMENT OF GEOGRAPHY

Measles, Mumps, and Rubella (MMR) vaccination.

A viral infection that's serious for children, it is one of the leading causes of death among young children. Before the introduction of the vaccination in 1980s, measles caused an estimated 2.6 million deaths each year.

the modern vaccination of Measles, Mumps, and Rubella (MMR) vaccination has two doses of vaccine recommended for children: the first dose is administered at 12-15 months of age and the second dose at 4-6 years of age.

The measles component in the MMR vaccine has been in use since 1968. The vaccine is so effective that the United States eliminated measles in 2000.

In general, the safety record of the MMR vaccine is good. Most

children who get the vaccine do not have any side effects. So far

the MMR vaccine has been linked with a very small risk of

seizures that lead to a fever and this risk increases as infants get

older. Other risks with the vaccine that include joint pain,

temporary arthritis, and a disorder that decreases the blood

platelet count are rarer.

Andrew Wakefield

The safety of the vaccine only became a controversy after Andrew Wakefield’s paper was published in 1998.

The paper showed a false link to autism from the MMR vaccine by using only 12 cases as evidence.

This flawed information was distributed widely by non-scientific journalism and mass media. As the result, many parents still do not believe the vaccine is safe even it has been further tested for safety.

Religious and Personal Belief Exemptions

Religious and personal belief exemptions for vaccination are allowed in all states in the U.S. except Mississippi and West Virginia.

California does not clearly recognize religion as a reason for claiming an exemption, however, the non-medical exemption in the state of California has Philosophical (Personal) Exemption can be use, so the reason of use exemption can be both religious and personal belief.

Research Question

This research proposes to examine vaccination and immunization rates according to different factors: Ethnicity (Caucasians or Hispanics)

Median household income (High - Low)

Personal belief rate (High - Low)

Religious belief rate*

*Since there has no data for religious belief rate, I use the number of churches instead.

Study Area Los Angeles County, with an

approximate population of ten thousands (Estimate in 2014: 10,116,705). There are 1672 kindergartens located within in Los Angeles County.

Data

On September 3, 2014, The Los Angeles Times released a list of thousands of kindergartens within the county containing each schools’ MMR vaccination rate and exemption rates. Original data is from California Department of Public Health

Number of population with ethnicity data and median household income in census 2013 data from U.S. Census Bureau.

Distribution of churches in Los Angeles County is provided by the USA churches from ArcGIS online.

Method and Analysis

ArcGIS to make spatial join and selection: Join churches with census tracts.

Select the tracts that contains kindergartens

Statistical analysis tool on Microsoft Excel

Due the skewness exists on all data, conversion is needed.

Analysis: Correlation

Analysis: Correlation (cont.)

Personal believe rate (2014) : positive correlation with personal belief exemptions, Caucasian

population, age and income

negative correlation with MMR vaccination rate and immunization rate

Hispanic population has quite strong positive correlation with vaccination rate.

Churches have very weak correlation with all variables except density of population.

Analysis: RegressionThis regression analysis used 2014 personal belief rates as a dependent variable.

32.4% of the variation in personal belief rates can be explained by the independent variables in table.

The significance F is far less than 0.05, H0 is rejected at significance level 0.05 so this regression is statistically significant.

Analysis: Regression cont.

Significance P-values in four independent variables; 2013 personal belief exemption rate, 2013 MMR vaccination rate, Caucasians and Hispanics are far lower than 0.05 significant level.

For every percentage of increased in the Caucasian population, their personal belief rates are increase by about 76%.

For every percentage increase in the Hispanic population, personal belief rates are decreased about 53.3.

For each percentage of vaccination rate increase, about 9% decrease in personal belief rate.

17.1% increase in personal belief rate for each percentage of median household income

Immunization and number of churches have p-value higher than 0.05 significance level so the relationship with personal belief rate are not clear.

Conclusion

This model has good explanation for the relationship between personal belief / exemption, vaccination and ethnicity population, however, the impact on the measles immunization is unclear.

Personal belief exemptions are very likely used by Caucasians

People with high median income in population is likely to use personal belief exemptions.

Hispanics and low income are unlikely to use personal belief exemptions, so they are likely to be vaccinated.

ACKNOWLEGEMENTS

Professor Julie Laity for research essay guidance

Professor Steven M. Graves for statistical analysis

Los Angeles Times for data (Plunge in kindergartners' vaccination rate worries health officials, September 3, 2014)