A health message that reaches everyone may change no one

Nok (a fictional character) is a district public health officer. Every rainy season she puts up dengue posters, sends messages to the village LINE group and speaks at the monthly meeting. This year more people saw her messages than ever. But when she walks round the houses, there are as many larvae in the water jars as before.

Many health communicators face the same question: if messages reach more people, why does behaviour not change? The four studies brought together here answer it from several angles.

Media reach rose every year, but knowledge and action did not follow

A study by Assoc. Prof. Dr Smith Boonchutima and colleagues (published in 2017, data collected 2013–2015) surveyed 7,772 people in 25 provinces over three years. How often people saw dengue information in the media rose every year, but the share of correct answers about the mosquito went up for one year and then fell back, from 73.6% to 81.5% and then 73.3%.

Action fared worse. The share eliminating breeding sites every week, as recommended, fell from 61.2% in 2014 to 48.3% in 2015. And the most stubborn misconception was about water: only about a third knew that the dengue mosquito does not lay eggs in dirty water. It survived two years of rising exposure, which suggests the messages sent out never confronted it directly.

Different groups want different messages

A study by Assoc. Prof. Dr Smith Boonchutima, Asst. Prof. Dr Teerada Chongkolrattanaporn and colleagues (published in 2020) surveyed 1,074 working women in 13 organisations. Women in private companies wanted animated video and infographics clearly more than the other groups, while women in government agencies and factories wanted plain text more than private-sector women did.

A study by Wechprasith and Asst. Prof. Dr Teerada Chongkolrattanaporn (published in 2022) of 400 retirees in Bangkok points the same way. Retirees met salt-reduction campaigns most on Facebook and least on radio and posters. Of eight demographic characteristics, only education and main source of income made a difference to health beliefs, and seeing the campaign more often was associated with beliefs only weakly or very weakly.

Knowing what to do is not the same as knowing why

A forum-theatre project on antibiotics in a peri-urban Yangon community (published in 2020), co-authored by Dr Phyu Hnin Hlaing, gives the clearest picture. Ten performances reached 1,175 people, and 36 of them stepped on stage to change the story. Afterwards most could say that antibiotics kill bacteria. But what happened on stage said more: most who stepped up simply told the sick character to see a doctor, without being able to explain why buying antibiotics over the counter is a problem, and those playing younger family members could barely persuade the elders.

Four points for the next health campaign

1. 1

   Find the misconception before making materials

   Ask the audience briefly what they get wrong, then write messages that correct that point directly, such as dengue mosquitoes and dirty water, instead of repeating general information every year.

2. 2

   Vary the format by group

   The same content should come in several forms: animation for people who prefer visuals, short readable text for those who still prefer to read, placed in the channels that group actually uses.

3. 3

   Let people try saying it themselves

   Activities in which the audience tries to persuade someone else, such as theatre or role play, reveal which reasons they still lack, something questionnaires rarely see.

4. 4

   Measure action, not just exposure

   Set indicators on behaviour, such as weekly larva control, alongside reach, because the two numbers can move in opposite directions.

Reading this evidence with care

The dengue data were collected in 2013–2015, before the centre was founded. Each year's respondents were a different group and the knowledge questions were not identical, so year-to-year comparisons show only rough direction. The working-women and retiree studies were conducted in Bangkok and its vicinity and are not nationally representative; the retiree study used an online questionnaire and so reached only internet users. The theatre project was evaluated through focus groups of 40 people on the day of the performance and did not follow behaviour over time.

Reach people first, then ask whether they changed

Reach is the first condition, not the destination. Health campaigns that work start by knowing what the audience thinks, tell the story in the form they want, and measure what they do.

If your organisation is planning health communication with hard-to-reach groups, the Center of Excellence in Communication Innovation at Chulalongkorn University's Faculty of Communication Arts would be glad to talk and share what we have learned.