A-LevelBiologyInfectious diseases9700/23 · Oct/Nov 2021 · Q511 Marks

Measles is a highly infectious disease. The World Health Organization (WHO) has coordinated a programme for controlling this disease by using vaccination.

(a)(i)Name the pathogen that causes measles.[1]
(a)(ii)Explain how the measles pathogen is transmitted.[3]
(b)Fig. 5.1 shows the number of cases of measles globally each month between January 2015 and March 2019. [Figure 5.1] Describe the pattern of measles cases as shown in Fig. 5.1.[3]
(c)Explain why measles has not yet been eradicated even though a vaccine has been available since the 1960s.[4]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[1] Morbillivirus ;
[3] any three from:
1 (pathogen is transmitted) in airborne droplets / as an aerosol ; A droplet infection / aerosol infection
2 breathed / sneezed / coughed / AW, out by infected person ;
3 (droplets) breathed in by, healthy / uninfected, person ;
4 touching surface with virus and, breathing into lungs / puts fingers in, nose / mouth ;
[3] any three from:
1 increase and decrease / fluctuates / AW; A between 2015 and 2019, over some of the years or just one year A increase, decrease and then increase for any one year 2015 to 2018
2 use of data to support mp1;
3 numbers for January 2019 are, highest / higher than other years or numbers for March 2019 are, lowest / lower than other years;
4 use of data to support mp3;
[4] ignore mutation and vaccine evasion / vaccine resistance ignore refs to cost any four from:
transmission and susceptibility (from mp1 to mp7)
1 infected person can infect many people / spreads easily in crowded conditions ;
2 measles spreads to children before they are vaccinated ;
3 vaccine cannot be given soon after birth because of passive immunity ;
4 immunisation rates do not reach 100% / ref to difficulty in reaching herd immunity / herd immunity is not achieved ;
5 herd immunity needed for protection of, unvaccinated people / babies ;
6 some people have, no / poor, response to vaccine ; A vaccine not always effective
7 ref. to malnutrition / ref. to lack of vitamin A ;
reasons for low immunisation rates (from mp8 to mp12)
8 difficult to reach all people, with example ; e.g. in rural areas areas of poor housing in big cities
9 collapse of vaccination programmes as a result of war / AW ;
10 lack of, trained professionals / health facilities;
11 many children do not receive boosters ;
12 reluctance to be vaccinated / ref. to anti-vaccination campaigns / ref to MMR or triple vaccine / lack of awareness about beneficial effects of vaccine / ref. to cultural or religious reasons / AW;
13 AVP; (for either section of the answer) e.g. ref. to any specific difficulty with contact tracing ref. to thermostability of vaccine and maintaining a cold chain migrants, with measles / from an area with an outbreak of measles