Lesson 4 Disease Outbreaks

The best way to ensure the safety of the population against a disease is by vaccination.

Various threatening illnesses that are characterized as vaccine preventable are still around us.

Smallpox is the only vaccine preventable illness that has completely disappeared

Polio is close to vanishing however it is still present in some countries.

However, as the vaccination rates increase the chances of a vaccine-preventable outbreak increase.

Other factors that can increase the chances of an outbreak are overcrowding, lack of proper sanitation, malnourishment and constant movement.

According to the WHO’s epidemics database, it was expressed that 400 outbreaks took place between 2005-2014 excluding measles which could have been prevented via vaccination.

An outbreak takes place when the levels of the illness exceed the expected ones.

Unfortunately, the greatest challenge for the protection against such illnesses is anti-vaccination sentiments. A number of immunization plans are negatively affected  by false or lack of information, personal, religious and other types of reasons that discourage them from getting vaccinated.

Since some diseases have become quite uncommon due to vaccinations , people forget how dangerous it can be if an outbreak takes place.

A high protection level must be acquired among the population in order to avoid transmission of infectious diseases. For example, because measles is very infectious a 95% of immunization among the population is needed to avoid outbreaks.

If the level of immunity is lower than 95%, it is very easy for an infected person to spark an outbreak in the population.


  • An outbreak of measles made a comeback in 2019.
  • In 1996, the highest number of measles cases was recorded however, this number was exceeded after 23 years.
  • In 2019, WHO reported a total of 869 770 cases in all of its regions.An increase in cases was detected up to 2019.
  • However, since 2016 the deaths caused by measles almost increased by 50%, estimating that 207 500  people died only in 2019.
  • it is suggested that the rise of measles cases and deaths has been due to the lack of vaccination of children with the MCV1 and MCV2 vaccines.
  • In order to avoid outbreaks, the level of vaccination must be at 95% to protect people from possible illness or even death. However, vaccination rates for MCV1 remained steady between 84 % & 85% for a decade, while MCV2 coverage has risen but only up to 71%
  • It is important to note that even though the COVID-19 pandemic has dominated the measles outbreak has not been resolved