World Immunization Week and vaccine confidence

The dengue vaccine scare that erupted last November prompted a fierce political and public reaction in the Philippines – yet another dengue immunization program in a Brazilian state has been unaffected. A leading vaccine confidence expert has drawn contrasts between outrage in Manila and relative calm in Parana state.

Vaccine scare stories are as old as vaccination itself. Public health experts shudder at the painful memory of the MMR vaccine catastrophe where a now-disgraced former doctor falsely linked the vaccine to developmental problems in children. Vaccination rates fell and measles outbreaks followed.

More recently, HPV vaccines – which prevent several cancers, including cervical cancer – are in the firing line. Concerns were raised that a small number of teenagers who had the shot later suffered chronic fatigue syndrome. This was not, initially, an unreasonable worry: parents naturally want to protect their kids from cancer but are equally careful to protect them from any side effects of medication or vaccines.

The issue was thoroughly investigated by the best experts in the world. They found that the rate of chronic fatigue symptoms in teenagers was the same before – and after – the vaccine was introduced. Yes, some adolescents were ill but it was not related to the HPV shot.

While vaccines are among the safest and most effective public health interventions in history, the public remains wary of an injection given to otherwise healthy people. And, when we make decisions for others – such as our kids or elderly relatives – the pressure to get it right is particularly acute.

So, the public is somewhat primed to overreact at the first whiff of a safety issue with any vaccine.

Suspension of a vaccine program

In late November 2017, dengue vaccine-maker, Sanofi Pasteur publicly shared data showing that people with prior dengue infections were best-suited to the dengue vaccine. There are four types of dengue and a second infection is often worse than the first. Because the body responds to vaccination in the same way as it would to an initial infection, it may not be advisable to vaccinate those who have never been infected by dengue.
Read why a second dengue infection is often worse than the first

In Parana, Brazil, where a public vaccination campaign had run for more than a year, authorities updated the vaccine’s label and got on with the job. In the Philippines, all hell broke loose. The government swiftly suspended the vaccination program and blamed its political predecessor for introducing the scheme in the first place.

‘The Philippines made headlines with public outrage and a suspension of the vaccine program, as well as threats to sue the manufacturer,’ says Dr. Heidi Larson of the Vaccine Confidence Project. ‘Brazil has stood by scientific evidence and, recognizing that the vaccine still has benefits although it carries some risk, it is facing this risk with resolve.’

Larson runs the Vaccine Confidence Index – a 67-country survey of attitudes to vaccination. She is a world-renowned expert on the factors that influence public perceptions, attitudes, and actions on vaccination. Larson told Break Dengue that the dengue vaccine scare has prompted her team to rerun their vaccine confidence survey in the Philippines.

‘One of the main things about the dengue vaccine story is that, compared to Brazil, the Philippines was much more fertile ground [for a vaccine scare],’ she said. ‘We look at some of the factors that can predict problems with vaccine confidence. They include low levels of underlying social trust, low trust in the political or health system, previous issues with vaccines – the kinds of things that historically have been amplifiers.’

Political issues have been part of the problem in the Philippines with the government keen to prosecute their rivals and criticise big business.

‘You have to appreciate the position politicians and leaders are in when faced with serious dengue outbreaks,’ notes Larson. ‘Dengue can have a real health impact and cause stresses on the overall health system. The vaccine was a source of hope but, for now, that opportunity seems to be lost in the Philippines.’

Spill-over effect

Now, the situation has taken another turn: the Philippines is suffering a measles outbreak. Spill-over from one vaccine panic to another is not uncommon.

‘There’s always a risk that anxiety or a loss of confidence in the system can have a knock-on effect,’ says Larson. The MMR scare somewhat dented uptake of other vaccines; a case of fraud in China that involved reselling out-of-date vaccines undermined confidence in pharmacies and immunization generally. ‘This creates generalized anxiety about vaccines. People wonder whether they are safe, whether the system is reliable, and may not be sure which vaccines were involved.’

Measles outbreaks are, unfortunately, occurring in many countries around the world despite the availability of a cheap, safe and effective vaccine. However, the Philippines epidemic appears to be linked to the dengue vaccine scare.

‘The people I’m in touch with on the ground feel that some of the reasons that people are refusing vaccines are linked to general anxiety following dengue vaccine,’ Larson says. ‘The outbreaks are in areas where the dengue vaccine was given.’

How did the dengue vaccine scare affect Brazil?

Given the reaction of authorities in the Philippines, it is somewhat surprising that other governments were not affected by contagion from the panic. Information spreads quickly online so the public and politicians in Parana, Brazil, will have been aware of events in Manila.

‘There are other contextual issues that can shape how society reacts,’ explains Larson. ‘Brazil has been through so much with Zika and yellow fever that they may have had panic fatigue. I think there is a threshold for public anxiety. There is only so much any country and any public can take.’

For now, it appears unlikely that people in the Philippines will have the option of getting the dengue vaccine. However, if public dengue immunization programs elsewhere deliver a clear reduction in dengue death rates – and reduced spending on hospitalization – then public opinion may turn. For the Philippines, this is unlikely to occur any time soon.

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