Stories of adverse events from vaccines matter – explained @ConversationUS

Stories of vaccine-related harms are influential, even when people don’t believe them

Laura Scherer, University of Missouri-Columbia; Brian Zikmund-Fisher, University of Michigan; Niraj Patel, University of Missouri-Columbia, and Victoria Shaffer, University of Missouri-Columbia

In 2013 a boy who was given the HPV vaccine died almost two months later.

Two quick questions: First, does this worry you? And second, do you believe that the vaccine caused the boy’s death?

This is a real case reported in the Vaccine Adverse Event Reporting System (VAERS). VAERS is monitored by health experts at the Centers for Disease Control and Prevention and Food and Drug Administration to detect very rare or emergent harms that may be caused by vaccines. The vast majority of adverse events reported in VAERS are mild (such as fever), but a few are serious, like death and permanent disabilities. Staff follow up on certain cases to better understand what happened.

A growing number of parents are refusing to vaccinate their children, and one reason they often state is that they do not trust that doctors and government agencies sufficiently research the potential harms of vaccines. Given that, we wanted to find out whether telling people about VAERS and the information it gathers could influence their beliefs about vaccine safety.

Vaccine refusal and the importance of trust

It’s important to stress that just because a case like the one mentioned above is reported to VAERS doesn’t mean that the vaccine caused the problem. That’s because VAERS is an open-access reporting system.

Health care providers are required to report certain adverse events, but they are not the only ones who can contribute to the database. Anyone can make a report in VAERS for any reason. Similarly, anyone can access VAERS reports and data. In fact, advocates both for and against vaccines refer to VAERS data as evidence of either the existence of harms or the rarity of harms.

This open-access feature makes VAERS a potentially rich source of information about possible vaccine-related harms. It also means, however, that the events reported in VAERS often turn out to have nothing to do with a vaccine.

Take for example, the boy who died less than two months after receiving the HPV vaccine. Here’s what the full VAERS report says: “Sudden death. He was perfectly healthy. The vaccination is the only thing I can think of that would have caused this. Everything else in his life was normal, the same.”

The fact that there were no reported problems for almost two months between the vaccine and the child’s death might make you, like us, skeptical that the vaccine was the cause. Yet, it is important that the death was reported so that it can be followed up.

Being transparent about risks is critical to building trust. In fact, that’s part of the reason that VAERS data is available to everyone.

Does VAERS make people trust vaccine safety?

It seems plausible that describing VAERS in depth could build trust. Doing so would demonstrate that every effort is being made to collect information about potential vaccine harms, and that even with such a comprehensive effort very few serious events are reported. Further, transparency would also show that these few serious events are not necessarily caused by the vaccine, and this information is available for anyone to view and evaluate.

We decided to test this idea in a recent internet survey. We surveyed over 1,200 people, who were divided into three groups.

One group received the standard CDC Vaccine Information Statement for the HPV vaccine. We chose the HPV vaccine because this vaccine is particularly underutilized. The second group was given detailed information about VAERS – what it is, what it is for and what it contains – as well as the number of serious adverse event reports received about HPV. To be specific, this group was told that there were seven deaths and 24 permanent disabilities reported for the HPV vaccine in 2013 out of a total of approximately 10 million vaccine doses given that year. A third group received all of that information and then also read the actual adverse event reports in detail. We hoped that reading these reports would show this group that not all of these deaths and permanent disabilities were caused by the vaccine.

We found that telling participants about VAERS, without having them read the actual reports, improved vaccine acceptance only very slightly. Even worse, when participants read the detailed reports, both vaccine acceptance and trust in the CDC’s conclusion that vaccines are safe declined significantly.

What we found next surprised us: The vast majority of our survey respondents, the same ones who were less accepting of vaccines and less trusting of the CDC, said that they believed the vaccine caused few or none of the reported deaths and disabilities. This means that the individual stories of perceived vaccine harms were highly influential, even when people didn’t believe they were true.

We are influenced by information even when we don’t believe it

Think back to your reaction to reading about the tragic death we described earlier. Our data suggest that just learning about this death may have caused you to feel more negatively toward the HPV vaccine, even if you believed that the vaccine did not cause the death.

While we can’t say that everyone reacted to the stories the same way or to the same degree, it seems clear that at least some people didn’t believe that the vaccine caused the reported harms, but they were nonetheless negatively influenced by those reports.

Systems like VAERS are essential for public health, providing an opportunity to learn about and investigate every possible case of potential harm caused by vaccines. But the power and emotion evoked by the stories of VAERS reports may influence us and undermine trust in vaccines, no matter what our rational mind might think.

The Conversation

Laura Scherer, Assistant Professor, Psychology, University of Missouri-Columbia; Brian Zikmund-Fisher, Associate Professor of Health Behavior and Health Education, University of Michigan; Niraj Patel, Graduate Student, University of Missouri-Columbia, and Victoria Shaffer, Associate Professor of Psychology, University of Missouri-Columbia

This article was originally published on The Conversation. Read the original article.

Rob Knell considers the relationship of monogamy and STDs @ConversationUK

How sexually transmitted diseases might have driven the evolution of monogamy

Rob Knell, Queen Mary University of London

Exactly why so many humans choose monogamous pair bonds over juggling multiple partners has long been a mystery to scientists. After all, having several partners at the same time should lead to more offspring – an outcome you’d think evolution would favour. Now a new study has linked the phenomenon to sexually transmitted diseases, arguing that monogamy could have evolved because it offered protection against the threat of infection.

Monogamy is, of course, the norm in Western societies. But there are many cultures where a husband can have more than one wife (polygyny) or, less commonly, a wife can have more than one husband (polyandry). This diversity of human mating systems is also hard to explain. What we do know, however, is that many hunter-gatherer societies, living in small groups, were most often polygynous (and many remaining groups still are). But with the rise of agriculture, societies tended to become more complex – and less polygynous. In the most strictly monogamous societies, there was often a social punishment for polygynists, either informally or, as in many modern societies, through a legal system.

Many explanations for this evolution have been put forward, including changes to the way that women chose their partners, such as being faithful to men who invested in provisioning for them. Another possibility is that groups of monogamists may have performed better than groups of polygynists. But the new research adds a further option: could an increased risk of infection from sexually transmitted infections associated with polygyny have contributed to – or even driven – the overall move from polygyny to monogamy?

Sexually transmitted diseases have been infecting humans for a long time. Prior to modern medicine, they also often caused significant harm – especially to the reproductive system. Clearly, these diseases infect polygynists more than monogamists, and it has been argued that when a polygynist and a serial monogamist have the same number of partners overall, the polygynist is more likely to pick up a dose of something nasty than the monogamist. According to computer modelling, this is because contact networks are more connected when you have concurrent partners than when you have serial partner change. Either way, overall, these effects could have had a big enough impact on the well-being of polygynists to allow monogamous individuals to take over a population.

The challenges of modelling

It’s certainly a good argument. But it’s hard to assess how likely it is to be true. This is because we know very little about the risk of sexually transmitted diseases in hunter-gatherer societies or historical societies transitioning to agriculture. This is a common problem in science: we can only make progress when we can test an idea, but plausible ideas are sometimes very hard to evaluate without massive effort.

One option in these cases is to do your experiment in the form of a computer simulation. This is what the researchers behind the new study did, modelling the impact of a bacterial sexually transmitted disease similar to gonorrhoea or chlamydia. Their results strongly back the hypothesis that such diseases could have triggered monogamy.

In their model, sexually transmitted diseases tend to “fade out” from small groups such as polygynist hunter-gatherers. This occurs because of random chance events that are more likely to be important in small groups, such as all the infected people suddenly getting better or dying. In larger, agricultural groups, however, such fade-out is much less likely, so sexually transmitted diseases tend to persist, damaging the health and reducing the birth rates of polygynists while allowing monogamists to take over.

What’s more, the monogamists that are most likely to take over a group for a long period are those that follow a “punishment strategy”, which fits with what we observe in many societies today.

So is the puzzle solved? Not quite yet. Computer simulations are useful and can tell us important things, but they are always limited and necessarily simplify the real world. In this case, for example, the researchers assumed that the disease they were modelling had similar pathological effects on men and women, whereas in reality many sexually transmitted diseases affect women more severely than men, potentially changing the effect of the disease on polygynists.

Further questions are raised by research into sexually transmitted diseases in animals, which hasn’t really found a clear relationship between promiscuity and disease. In fact, computer modelling work focused on animals has found that promiscuous and monogamous individuals can coexist even in the presence of a dangerous disease. What’s more, there are examples of highly promiscuous animals which are heavily infected with sexually transmitted diseases yet carry on regardless (two-spot ladybirds in Continental Europe are one example, believe it or not).

As the researchers themselves point out, there are indeed some challenges associated with this idea. More detailed simulations or better data on sexually transmitted infections in societies where people live in small groups would make the picture clearer. For now, it remains an intriguing and plausible suggestion that we should explore further. Given the continuing threats posed by sexually transmitted diseases today it’s surprising that it’s taken this long for someone to put two and two together and suggest that the advent of monogamy may have served a very practical purpose.

The Conversation

Rob Knell, Senior Lecturer, Queen Mary University of London

This article was originally published on The Conversation. Read the original article.

Measles and Pertussis outbreaks tied to vaccine refusal @NIHDirector #science

Parents have a responsibility not only to their own children, but to their communities—it’s only by achieving a very high level of population immunity that outbreaks can be prevented. Vaccination is particularly crucial for children with cancer and other diseases that cause immunosuppression. They cannot be vaccinated safely, but are at high risk of severe consequences if they are infected—and, thus, they depend on the community’s so-called “herd immunity” for protection against a potentially fatal illness.

While some parents continue to express concern about a possible link between vaccines and autism spectrum disorders, the original report claiming this connection has been debunked and retracted.  A large number of carefully designed follow up studies have been carried out, and the overwhelming weight of scientific evidence shows no evidence for such a link. That’s why it continues to be so important to get the word out to parents: Have your kids vaccinated.

Top 6 #GMO news stories from @GeneticLiteracy #GLPTop6!


  1. Moms Across America claims GM salmon not kosher, but Jewish law, tradition say otherwise by Stephan Neidenbach

  2. Cellular clock may help improve cancer treatment, forensic science by Nicholas Staropoli

  3. Genetic engineering in Africa: Part 1: Bananas and Cassavas  || Part 2: Cautious embrace of biotechnology by Steven Cerier

  4. Enviro activists reject synbio solution for Indonesian palm oil-orangutan crisis by Nicholas Staropoli

  5. Life without allergies? Detecting genetically-based food allergies at birth by Meredith Knight

  6. Knowledge of genetic risks from personal DNA tests may not help in changing behavior by Arvind Suresh