From time to time, the CDC committee that makes recommendationsabout vaccines (ACIP) decides to “change their minds†about the useof a particular vaccine, even though we might have been using itfor a long time. Each time they do this, there is something aboutthe “old†vaccine they didn’t like, and something about the “newâ€vaccine that fixes the problem. For each of the following, explain(1) the difference between how the old and the new vaccinesfunction, and (2) how the new vaccine avoids some problem with theold one. If the new vaccine introduces some problem of its own,describe that, too.
A. In 1983 a 23-valent pneumonia vaccine was developed using thepolysaccharide capsules from 23 different Strep pneumoniae strains,and was used for elderly people. But in 2015 the ACIP recommendedswitching to a 13-valent polysaccharide-protein conjugate vaccine(Prevnar-13).
B. In 1997 the recommendation was made to switch from awhole-cell Pertussis vaccine, which had been in use since 1949, toan acellular subunit vaccine.
C. In 1961 we switched from an inactivated Polio vaccine(developed in 1955) to a live attenuated one. Then in 2000 weswitched back to the inactivated one. Explain both ACIP decisions.D. In the near future, the decision may be made to switch from thecurrent Flu vaccine (either the live attenuated or the inactivatedone) to a DNA-based flu vaccine.
