Vaccines - Sociological aspects

The readings for class 3 discussed some important reasons for the controversies that surround childhood vaccinations, highlighting issues such as vaccine ingredients, allergies and grouping these into nine pertinent categories. The readings also traced the roots of the problem and laid bare the theme at the center of it all : human nature.

With regard to the malarial vaccines, human social behaviour has been refined. Since there has been no vaccine commercially available so far, there has been no hue and cry yet.

The only malarial vaccine that has ever reached phase III clinical trials is the RTS,S, a subunit vaccine containing pre erythrocytic circumsporozoite protein (RTS) fused to the Hepatitis B surface antigen (B)  (Lell B et al., 2009; WHO, 2009).

INTENDED TARGET GROUPS
The vaccine when commercially available will be primarily used in countries where malaria is endemic. In countries like the United States, where malaria is not endemic, the vaccine will probably be made available to people intent on travelling to international locations that are endemic.

WILL VACCINE EFFICACY PLAY A ROLE IN ITS ACCEPTABILITY ?

The vaccine at the heart of the childhood vaccine controversy , the MMR vaccine, has an efficacy of >90 percent. In phase II clinical trials conducted in Kenya and Tanzania, the RTS, S ,vaccine had an efficacy of only 52.9 % in children aged 5 to 17 months , who had been given a primary dose and two boosters.  That is, only 53 people out of every 100 who are vaccinated could fight off an infection with wild type parasite. One could think that this could play a role in the acceptance of the vaccine by communities. It appears however that parents, in countries that are the intended target groups for the vaccine, perceive the risk of vaccination as being  lower than the risk of contracting the disease itself.

Studies in central Ghana suggest that parents prefer the vaccine over prophylactic malarial drugs and that they are willing to add malarial vaccines to the myriad of other vaccines their children receive (Febir L et al., 2013).

AWARENESS GAPS ....  WHERE EXPECTED, NONE EXIST !

Contrary to established narrow-minded expectations, field work in Mombazique showed that awareness about malaria and vaccines were very high.  To quote Bingham et al., 2012, "Vaccines are seen as means to reduce the threat of childhood illnesses and to keep children and the rest of the community healthy"

Properly disseminated knowledge and the experience that stems from facing the deadly disease have made the target population wise. They do not seem to have fallen prey to their own intellect like the few in developed nations who reject childhood vaccinations.

THE THING WITH DOSES AND INGREDIENTS

So far, three doses of the vaccine are required to achieve effective immunity. If newer more efficacious adjuvants are not available soon, the cost of protection could be extraordinarily high. This can result in policy constraints in immunizing adults as well as children.

Also, since the vaccine has subunit antigens there will be no multiplication inside the vaccinated human and no spread of immunity (the spread of live vaccine poliovirus  conferred immunity on exposed people as well). Herd immunity can be established only by vaccinating every individual.

To date, the adjuvant AS01, which contains monophosphoryl lipid A from LPS of Salmonella minnesota (Mata E. et al.,2013), has had a safe track record. But, if any adverse effect ever occurs, it can well be expected that the first ingredient in the vaccine that will be considered worthy of blame will be the adjuvant, since the proof of concept of using the RTS has been validated by use with other adjuvants such as AS02.

In conclusion, malarial vaccines will be well received when they are approved and marketed.

References

Lell B, Agnandji S, von Glasenapp I, Haertle S, Oyakhiromen S, Issifou S,
Vekemans J, Leach A, Lievens M, Dubois MC, Demoitie MA, Carter T, Villafana T,
Ballou WR, Cohen J, Kremsner PG. A randomized trial assessing the safety and
immunogenicity of AS01 and AS02 adjuvanted RTS,S malaria vaccine candidates in
children in Gabon. PLoS One. 2009 Oct 27;4(10):e7611.

Febir LG, Asante KP, Dzorgbo DB, Senah KA, Letsa TS, Owusu-Agyei S. Community
perceptions of a malaria vaccine in the Kintampo districts of Ghana. Malar J.
2013 May 7;12:156.

Bingham A, Gaspar F, Lancaster K, Conjera J, Collymore Y, Ba-Nguz A. Community
perceptions of malaria and vaccines in two districts of Mozambique. Malar J. 2012
Nov 28;11:394.

Mata E, Salvador A, Igartua M, Hernández RM, Pedraz JL. Malaria vaccine
adjuvants: latest update and challenges in preclinical and clinical research.
Biomed Res Int. 2013;2013:282913. doi: 10.1155/2013/282913. Epub 2013 Apr 23.
PubMed PMID: 23710439; PubMed Central PMCID: PMC3655447.