Vaccination can protect individuals from infectious disease.
Rotavirus is a highly contagious virus that causes severe gastroenteritis, particularly in infants.
Suggest the primary biological component of a typical rotavirus vaccine.
Describe the role of T-lymphocytes in the development of immunity against a viral pathogen such as the rotavirus.
The table below shows the recorded annual number of rotavirus cases in a certain region around the time a national vaccination programme was introduced:
YearNumber of cases201218,0002013 (vaccine introduced)15,00020146,00020162,700\begin{array}{|c|c|} \hline \text{Year} & \text{Number of cases} \\ \hline 2012 & 18,000 \\ \hline 2013 \text{ (vaccine introduced)} & 15,000 \\ \hline 2014 & 6,000 \\ \hline 2016 & 2,700 \\ \hline \end{array}Year20122013 (vaccine introduced)20142016Number of cases18,00015,0006,0002,700Calculate the percentage decrease in recorded cases of rotavirus between 2013 and 2016.
A student wants to use the percentage decrease from (b)(i) to draw conclusions about the effectiveness of the rotavirus vaccine. Another student argues that 2014 would be a better starting year for the calculation.
Suggest two reasons why 2014 might be a better starting year than 2013.
In the late 2020s, the number of rotavirus cases in this region fell to fewer than 10 per year. Suggest one way in which the yyy-axis scale of a trend graph covering 2012 to 2030 could be changed so that fluctuations in both high-case and low-case years are visible.
