PUBH 3100 Week 6 Prevention Argument Example

Vaccinate Before Infection or Scan After It? A Prevention Argument Setting Hepatitis B Vaccination Against Ultrasound Surveillance for Liver Cancer, Each Fixed to the Stage It Can Reach

Student Name

Walden University

PUBH 3100: Human Disease and Prevention

Instructor Name

Month Day, Year

Vaccinate Before Infection or Scan After It? A Prevention Argument Setting Hepatitis B Vaccination Against Ultrasound Surveillance for Liver Cancer, Each Fixed to the Stage It Can Reach

The Question

Hepatocellular carcinoma, the cancer that most often arises in liver cells themselves, often develops after years of chronic hepatitis B infection. Two kinds of prevention are available. Primary prevention stops the infection before it starts, through hepatitis B vaccination. Secondary prevention looks for cancer early in people who are already infected, through regular liver ultrasound, so that tumors can be treated while small. This paper argues that primary prevention should be the main public health priority, fixes each action to the stage of the disease it can reach and then gives the strongest counterargument a full hearing.

The Course of the Disease

Infection with hepatitis B virus can be cleared or can become chronic. Chronic infection is far more likely when infection happens at birth or in early childhood than in adulthood. Over years and often decades, chronic infection can cause liver inflammation, scarring and cirrhosis, and it raises the risk of liver cancer even without cirrhosis. A global review estimated that 3.61% of the world's population carried the hepatitis B surface antigen, the marker of current infection, with prevalence above 8% in the African region (Schweitzer et al., 2015). The stages relevant here are susceptibility before infection, chronic infection without cancer and early cancer that has not yet caused symptoms.

Primary Prevention: Vaccination Reaches the First Stage

What It Does

Hepatitis B vaccine, given to infants starting at birth, prevents infection and therefore prevents the chronic infection that leads to most hepatitis B-related liver cancer. It acts at the stage of susceptibility, before the disease process begins.

The Evidence

Taiwan began universal infant hepatitis B vaccination in 1984. Among children aged 6 to 14, the average annual incidence of liver cancer fell from 0.70 per 100,000 in 1981 to 1986 to 0.36 per 100,000 in 1990 to 1994, and among children aged 6 to 9 it fell from 0.52 for those born between 1974 and 1984 to 0.13 for those born between 1984 and 1986 (Chang et al., 1997). Because the study compared birth cohorts before and after the program rather than randomizing children, other changes over time could contribute, but the size and timing of the decline, matching vaccinated cohorts, make vaccination the most plausible explanation.

Secondary Prevention: Surveillance Reaches the Third Stage

What It Does

Surveillance offers people with chronic hepatitis B regular ultrasound, sometimes with a blood test for alpha-fetoprotein, so that tumors are found while small and can be removed. It cannot prevent infection or cancer; it acts on cancer already present but not yet causing symptoms.

The Evidence

A randomized trial in China assigned people with chronic hepatitis B, or a history of chronic hepatitis, to be screened every six months or not. Despite only 58.2% completing the offered screening, the screened group had a liver cancer death rate of 83.2 per 100,000 compared with 131.5 in the control group, a rate ratio of 0.63, and far more cancers were found small enough to remove (Zhang et al., 2004). That is real benefit, measured as deaths, which is immune to lead time.

Why the Stages Decide the Comparison

The comparison between the two actions is not a contest between two equally placed tools. Vaccination works before the first stage of the disease process, so it prevents infection, chronic disease, cirrhosis and cancer together. Surveillance works only at the last stage before symptoms, so it cannot reduce the number of people who develop cancer, only the number who die of it, and only among those already identified as infected and willing to return every six months. A third point matters as well: the 58.2% completion rate in the trial shows how hard it is to keep people in a lifelong surveillance program. Fixing each action to its stage explains why their effects differ in kind, not only in size, and why their costs and demands on people differ too.

The Argument for Primary Prevention

Vaccination reaches the whole population before infection and removes most future cases entirely. Surveillance reaches only people already known to be infected, which requires testing to find them, and it reduces deaths among those whose cancers it finds, not the number who develop cancer. Vaccination is given once in infancy; surveillance requires lifelong scans twice a year. For a population, preventing infection prevents more cancer at lower cost, and it also prevents the cirrhosis and liver failure that chronic infection causes even when cancer never appears.

The Counterargument

The strongest objection is time. Vaccinating infants today prevents liver cancers that would have appeared decades from now. Hundreds of millions of adults already carry chronic hepatitis B, and vaccination does nothing for them. For those adults, surveillance, along with antiviral treatment, is the only prevention available, and the Chinese trial shows it reduces deaths. A public health program that invested only in vaccination would accept preventable deaths among people already infected for the next forty years.

Answering the Counterargument

The objection is correct, and it changes the position from "vaccination instead of surveillance" to "vaccination first, surveillance for the already infected." The two actions do not compete for the same people, and they need not compete for the same budget line either: vaccination serves those not yet infected, surveillance serves those who are. The priority claim holds for a population's future, because only vaccination shrinks the pool of people who will ever need surveillance. But a program that ignored current carriers would fail the people the counterargument names, so surveillance belongs in the plan as the action fixed to their stage.

Summary

Hepatitis B vaccination acts before infection and has been followed by large declines in childhood liver cancer. Ultrasound surveillance acts after infection and reduces liver cancer deaths among those screened. Vaccination should come first because it prevents the disease for whole cohorts, while surveillance remains necessary for people already infected, who vaccination cannot reach.

References

Chang, M.-H., Chen, C.-J., Lai, M.-S., Hsu, H.-M., Wu, T.-C., Kong, M.-S., Liang, D.-C., Shau, W.-Y., & Chen, D.-S. (1997). Universal hepatitis B vaccination in Taiwan and the incidence of hepatocellular carcinoma in children. The New England Journal of Medicine, 336(26), 1855-1859. https://doi.org/10.1056/NEJM199706263362602

Schweitzer, A., Horn, J., Mikolajczyk, R. T., Krause, G., & Ott, J. J. (2015). Estimations of worldwide prevalence of chronic hepatitis B virus infection: A systematic review of data published between 1965 and 2013. The Lancet, 386(10003), 1546-1555. https://doi.org/10.1016/S0140-6736(15)61412-X

Zhang, B.-H., Yang, B.-H., & Tang, Z.-Y. (2004). Randomized controlled trial of screening for hepatocellular carcinoma. Journal of Cancer Research and Clinical Oncology, 130(7), 417-422. https://doi.org/10.1007/s00432-004-0552-0