Module 2 of 5
Core principles of disease prevention. Vaccines, hygiene, and community-level protective behaviors.
This content is for educational purposes only. It does not constitute medical advice, diagnosis, or treatment. All health decisions — especially regarding pregnancy, child health, medications, and mental health — should be made in consultation with a qualified healthcare professional. If you or someone you know is experiencing a medical emergency, seek care immediately.
Samuel is a primary school teacher in Kakamega, Western Kenya. Every rainy season, his school loses students for weeks at a time to diarrheal disease, malaria, and respiratory infections. He has started to think of it as inevitable — 'that is just how things are when the rains come.' His neighbor, a community health worker named Beatrice, disagrees. She has been tracking which households have the highest rates of illness. Almost without exception, they are the same households: the ones with uncovered water storage, no latrines, children who have missed vaccines, and no habit of handwashing before eating.
Samuel's school does not have a disease problem. It has a prevention gap. This module is about closing it.
Prevention is not a single action — it is a layered strategy. Public health professionals organize prevention into three tiers, and understanding all three helps community health workers identify where to focus their energy.
Primary Prevention stops disease before it begins. Vaccination, safe water, sanitation, bed nets for malaria, handwashing — these are primary prevention tools. They work at the population level. When everyone in a community practices good hand hygiene, the overall disease burden drops for everyone — including those who occasionally forget.
Secondary Prevention catches disease early, before it becomes severe. Screening for hypertension, antenatal care visits that detect complications, tuberculosis contact tracing, and community-level monitoring of child growth are all secondary prevention. The goal is to find problems when they are still small and treatable.
Tertiary Prevention manages existing disease to prevent it from worsening or causing additional harm. Medication adherence for HIV or diabetes, rehabilitation after injury, and mental health support for chronic illness all fall here. This is largely the work of clinics — but community health workers play a critical role in supporting adherence and follow-up.
The most cost-effective prevention is always primary — stopping disease before it happens. But primary prevention requires community-wide behavior change, and behavior change requires trust, relationships, and sustained engagement. That is exactly what community health workers provide.
Every $1 invested in vaccination generates $54 in economic returns when including the full cost of illness, lost productivity, and premature death.
Source: WHO — The Immunization Agenda 2030; published in Health Affairs (2021)
Kenya's Expanded Programme on Immunization (KEPI) is one of the most important public health tools in the country. It provides free vaccines at all government health facilities. As a community member or CHW, knowing this schedule is not optional — it is essential knowledge that can save a child's life.
The core vaccines on the Kenya routine immunization schedule include:
At birth: BCG (tuberculosis protection) and OPV-0 (polio)
6 weeks: OPV-1, Pentavalent-1 (protects against diphtheria, pertussis/whooping cough, tetanus, hepatitis B, and Hib meningitis), PCV-1 (pneumococcal/pneumonia), and Rotavirus-1 (diarrheal disease)
10 weeks: OPV-2, Pentavalent-2, PCV-2, Rotavirus-2
14 weeks: OPV-3, Pentavalent-3, PCV-3, IPV (inactivated polio)
6 months: Vitamin A supplementation begins
9 months: Measles-Rubella vaccine (MR1) and Yellow Fever (in endemic counties)
18 months: MR2 booster
A community health worker who knows this schedule can identify unvaccinated children during home visits, educate parents who are hesitant, and link families to the nearest facility offering free vaccines. This is not complicated. It is enormously impactful.
This is not an exaggeration. Handwashing with soap at critical moments prevents 30-40% of diarrheal illnesses and approximately 20% of respiratory infections. In communities where diarrheal disease kills children and respiratory infections fill clinics, handwashing is not a basic hygiene tip — it is a clinical-grade intervention.
The critical moments for handwashing are:
After using the toilet or latrine
After cleaning a child who has defecated
Before preparing food
Before eating
Before and after caring for a sick person
After handling animals or animal waste
The technique matters. Wetting hands, applying soap, scrubbing for at least 20 seconds (including the backs of hands, between fingers, and under nails), rinsing thoroughly, and drying with a clean cloth or air-drying — each step reduces pathogen transmission. Water alone removes approximately 23% of bacteria. Soap and water removes more than 99%.
In communities without reliable clean water or soap, ash or sand can provide minimal protection, but the promotion of accessible handwashing stations — tippy taps made from locally available materials cost less than 50 Kenyan shillings to build — is a practical community health intervention that any CHW can facilitate.
Foodborne illness is dramatically underreported and underappreciated as a disease burden. In East Africa, contaminated food causes an estimated 91 million illnesses and 137,000 deaths annually — disproportionately affecting children under 5.
The WHO Five Keys to Safer Food provide a simple, evidence-based framework:
Keep clean — wash hands, surfaces, and utensils before and during food preparation. Keep cooking and serving areas free from insects and pests.
Separate raw and cooked — never use the same knife or surface for raw meat and ready-to-eat food without washing thoroughly in between. Store raw meat away from other foods.
Cook thoroughly — heat food to at least 70°C internally. This kills most pathogens. In practice: make sure meat juices run clear, boil soups and stews to a rolling boil.
Keep food at safe temperatures — bacteria multiply rapidly between 5°C and 60°C. Eat food while still hot or reheat thoroughly. Do not leave cooked food at room temperature for more than 2 hours.
Use safe water and raw materials — use clean water for drinking and food preparation. Wash fruits and vegetables with clean water. Avoid food with mold or unknown origin.
M-TIBA is a mobile health savings platform developed by PharmAccess Foundation in partnership with Safaricom. It allows users to save money specifically for healthcare costs using M-Pesa, with contributions from family members, employers, or development partners.
By 2022, M-TIBA had registered over 3 million users across Kenya — the majority of them in low-income urban and peri-urban settings where out-of-pocket health costs routinely prevent people from seeking preventive care. Analysis showed that M-TIBA users were significantly more likely to attend antenatal care visits, seek care early rather than waiting until illness was severe, and complete treatment courses.
The insight: financial barriers to prevention are as important as knowledge barriers. A community health worker who knows that a family cannot afford clinic transport can use tools like M-TIBA as part of their prevention toolkit — not just education, but practical financial navigation.
In Kenya, only 56% of children under 1 year old are fully immunized according to the national schedule — meaning nearly half of infants are partially or completely unprotected from preventable diseases.
Source: Kenya Demographic and Health Survey (KDHS) 2022, Kenya National Bureau of Statistics
Conduct a simple prevention assessment using the checklist below.
You can do this for your own household first, then use it as a template for community visits. Ask these yes/no questions: Is the water source covered and protected from contamination? Is there a latrine or toilet, and is it used by all household members? Is there soap and water available at the handwashing point? Are all children under 5 up to date on the KEPI vaccination schedule (check the Road to Health booklet)? Is food stored covered and away from animals? Is there a mosquito net, and is it used every night?
Score the household and identify the top priority gap.
Six yes answers = strong prevention. Four or fewer = significant risk. Write down the single biggest gap and the simplest action that would address it. Not a comprehensive plan — one action. That specificity is what makes community health work effective.
Research where the nearest free vaccination point is for your community.
Go to the Kenya Ministry of Health website (health.go.ke) or ask at your nearest dispensary. Write down: the facility name, distance from your community, and days/times vaccines are available. This is the piece of information that converts a hesitant parent from 'I should vaccinate' to 'I know exactly where and when to go.'
Prevention is not a luxury — it is the highest-return investment in health that any community can make. A CHW who prevents one case of cholera has done more than a clinic that treats ten.
Want to go further? These free resources are the next step:
Kenya Expanded Programme on Immunization (KEPI) — Official vaccination schedule and facility finder health.go.ke/immunization
WHO Five Keys to Safer Food — Free poster, training materials, and videos — available in Swahili who.int/news-room/feature-stories/five-keys-to-safer-food
WASH in Schools — UNICEF Kenya — Practical resources for community-level sanitation and hygiene promotion unicef.org/kenya/water-sanitation-and-hygiene
Answer this question before completing the module
Think about the most common illness or health problem in your household or immediate community. Write a short prevention plan — at least three specific actions people could take before that illness occurs — and explain why each action matters.
Score 2 out of 3 to complete this module
1. Which of the following is an example of primary prevention?
2. Kofi washes his hands carefully with soap and water after using the toilet and before preparing food. Why is this habit especially important in communities where clean water access is limited?
3. A community health worker wants to reduce malaria cases in her village. Which combination of prevention measures is most likely to be effective?