Question

From time to time, the CDC committee that makes recommendations about vaccines (ACIP) decides to “change their minds” about the use of a particular vaccine, even though we might have been using it for a long time. Each time they do this, there is something about the “old” vaccine they didn’t like, and something about the “new” vaccine that fixes the problem. For each of the following, explain (1) the difference between how the old and the new vaccines function, and (2) how the new vaccine avoids some problem with the old 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 the polysaccharide capsules from 23 different Strep pneumoniae strains, and was used for elderly people. But in 2015 the ACIP recommended switching to a 13-valent polysaccharide-protein conjugate vaccine (Prevnar-13).

B. In 1997 the recommendation was made to switch from a whole-cell Pertussis vaccine, which had been in use since 1949, to an acellular subunit vaccine.

C. In 1961 we switched from an inactivated Polio vaccine (developed in 1955) to a live attenuated one. Then in 2000 we switched back to the inactivated one. Explain both ACIP decisions. D. In the near future, the decision may be made to switch from the current Flu vaccine (either the live attenuated or the inactivated one) to a DNA-based flu vaccine.

Answer 1

A. The 13-Valent pneumococcal polysaccharide vaccine was actually developed for administring to and protecting children below 2 years of age. The reason this was so is because the 23-valent pneumococcal polysaccharide vaccine does not elicit a protective immune response in children below 2 years of age. The 23-valent pneumococcal polysaccharide vaccine triggers a T-cell independent immune response and this is not possibe in children below 2 years of age. Thus the need for 13-Valent pneumococcal polysaccharide vaccine .

B.Whole-cell pertusis vaccines cause redness and swelling at the site of the injection when administered to adolescents and adults and the reaction actually is age dependent and it increase as the person ages. Therefore, to mitigate these adverse reactions Pertusis sub unit vaccine was developed and used. These vaccinces contain purified components of B.pertussis.

C.IPV was replaced by OPV as it was easier to administer for an entire population through mass vaccination campaigns, it elicited a superior induction of mucosal immunity in the gut as well as costed less to produce. But OPV was reintroduced in routine administration because IPV resulted in vaccine-associated paralytic poliomyelitis in certain individuals of the population.

D. There is constant antigenic drift in HA proteins that creates susceptibility in humans to fall sick with this virus. Therefore cell culture based vaccines are the future in terms of HA where in cell subtrate DNA are being researched to produce them into vaccines.