Dengue: Study reveals drastic fall in the vaccine’s confidence, safety and efficacy

Publicação: 9 de November de 2018

Fast dissemination of misinformation is undermining the confidence in vaccines crucial to public health, warns Dr. Heidi Larson

Findings emphasize the importance of identifying gaps or collapses in the general public’s confidence in vaccines, so trust can be reestablished before pandemic strikes

A recent study led by the London School of Hygiene and Tropical Medicine (LSHTM) measured the impact of the Dengvaxia dengue vaccine crisis, on overall confidence before and after the manufacturer disclosed the risk associated with the vaccine and the related political consequences. According to the research published in Human Vaccines & Immunotherapeutic, the highly politicized response of the Philippines government to the risks reported regarding the vaccine led to a drastic decrease of public trust in vaccines.

The Vaccine Confidence Project TM measured the impact of this crisis, comparing the confidence levels from 2015, before the incident, to the recent 2018 levels. According to the results, the confidence of those who agree vaccines are safe decreased from 82% in 2015 to only 21% in 2018. Similarly, confidence on vaccine efficacy decreased from 82% in 2015 to only 22%. The numbers also showed a drop when assessing the importance of vaccine, decreasing from 93% in 2015 to 32% in 2018.

The main author, Professor Heidi Larson, Director of the Vaccine Confidence Project at the LSHTM and her co-author Ken Hartigan-Go stress that the results demonstrate not only the need for an effort to rebuild public confidence in vaccines, but also to build confidence in health authorities who became victims during this drama in the Philippines. “The public seems to forget that there was a serious outbreak of dengue fever and a new vaccine approved by the Philippines, was released to solve this serious public health problem”, says Dr. Larson.

Now the goal is to rebuild public confidence. The research’s authors claim to be optimistic that this is possible. For such, according to them, the first step is to monitor social networks spreading false information that scare the public. Secondly, politicians must ensure impartial investigations. Thirdly, the government’s health agency, along with the WHO, can be more proactive in the disclosure of education campaigns warning about the risks. Finally, the scientific community must ensure that only experts with proven experience are allowed to give their assessments.

Noise in the media can be a threat to public health

Dr. Larson explains that when conflicting of manipulated data are not adjusted, but rather repeated, they may become absolute truths.  This way, rumors, false information or misinformation can lead people to wrong decisions, for example, refusing to be vaccinated, allowing the spread of infectious diseases, because if there are not enough vaccinated people, viruses can spread more easily. “When society and decision makers choose the wrong information, they might make dangerous decisions, such as rejecting well-informed health programs and policies and rejecting preventive health care”, she adds.

Still according to the author, a well-informed society is a critical society able to distinguish where and which information are correct, i.e., in case of a possible epidemic, misinformation will not be propagated. Social media campaigns play a key role in spreading accurate information to stop or contest negative or harmful information. Dr. Larson points out that perhaps social media platforms need to re-examine their critical role in influencing the public, this can be a valuable tool to mobilize the public for health improvements.

“It is very important to build social networks of informed and critical thinkers and supporting the systems before another pandemic. If there were a pandemic next month in the Philippines, it would be difficult to gain full public trust and cooperation if, for example, an influenza vaccine campaign was launched. Now it is time to build – and rebuild – confidence networks, before another pandemic”, she alerts.

Vaccine Confidence Project prepares people to face the results of confidence crisis

The Vaccine Confidence Project continuously monitors media, public concerns surveys and globally gathered information for a collaborative network to help predicting and approaching vaccine confidence issues before they explode in refusal crisis. Situations and experiences similar to those in the Philippines help to train and prepare others for any confidence crisis outcomes.

“Those groups and individuals who are undermining valuable and proven interventions for public health, such as vaccines, must be held accountable. A line that needs to be drawn. Individuals must, of course, ask questions and have the opportunity to discuss any concerns with their doctor or other health care professional, but those who impose false information to purposely divert people to a life-saving intervention should be held accountable”, concludes Dr. Larson.

Dengvaxia case, the dengue vaccine

The investigation was started by the Philippine Congress, immediately after the Sanofi Pasteur announcement, on November 29, 2017. In the sequence, the immunization program conducted by the Philippine Health Department was suspended in four regions in the country. The vaccine was still available in private clinics. In January 2018 the Philippine FDA General Director revoked the vaccine´s marketing authorization, making it unavailable even in private clinics.

The first country to use the vaccine in the public sector was the Philippines, initially in three pilot regions in the Country, where the dengue load was greater from 2012 to 2015. The Country was not entirely vaccinated, i.e., only some regions received the vaccine (mass vaccination was not the terminology used in the Philippines). Everything points to the fact that the vaccination campaign was not interrupted after the report by the WHO, but by Sanofi Pasteur and the consequent Congress investigation that lead the Philippine Health Department to suspend the public immunization program.

The Philippine Health Department has fined Sanofi in USD 2 thousand. The measure was a consequence of the information disclosed by the company, in November, 2017, where, according to preliminary studies, individuals who had not acquired the disease previously developed the most severe forms of the disease.

The Philippines vaccinated over 700 thousand children above 9 years-old since 2016.

Dengvaxia in Brazil

Dengvaxia marketing in Brazil, by Sanofi Pasteur, is still allowed, but its use is no longer indicated for those who never had the disease, and the product’s leaflet has been modified.  The Brazilian Ministry of Health, however, has not yet promoted mass vaccination campaigns with the substance, which is available in private vaccination clinics.

Until today, it is the only vaccine against dengue released for sale in Brazil, and is not a consensus among doctors, organs and specialists. In a joint note, the Brazilian Society of Tropical Medicine (SBMT), the Brazilian Society of Immunizations (SBIm), the Brazilian Society of Pediatrics (SBP), the Brazilian Society of Infectiology (SBI) and the Brazilian Federation of Associations of Gynecology and Obstetrics (Febrasgo) have reported that assessing the use of the vaccine in public programs is worthy of another look – that of risk and benefit assessment – and that the introduction of the dengue vaccine into public programs becomes even more challenging. Read the document.

The Brazilian Society of Collective Health (ABRASCO) said there were doubts regarding the vaccine’s effectiveness and remembered the Philippines was the first country to use it for mass vaccination, but suspended it after the WHO report. The association also questioned which measures were taken by the Unified Health System (SUS) regarding this fact. Find here the public notice. 

Sanofi Pasteur Medical Director, Sheila Homsani, sent the company’s formal statement regarding dengue vaccine Dengvaxia®. The document states that Sanofi Pasteur held an exploratory study, presented to the regulatory agencies, that confirmed that Dengvaxia is a vaccine with important role in the public health systems of endemic countries, such as Brazil, since it kept the efficacy along the 72-month study period. Find the notice

The Ministry of Health also issued a notice in response and clarified that while all studies are not finalized, it will not take the decision to include a vaccine against dengue in the National Vaccination Calendar, and accordingly, there are no elements to introduce Dengvaxia® in the SUS vaccination services. Find the document.

The vaccine is indicated for patients from 9 to 45 years-old who already had dengue. Test is performed with Fingerstick Whole Blood but is not available at the SUS nor is sold in drugstores. Three doses of the vaccine are needed, one every six months.