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Understanding the Risks Versus the Myths of Vaccines

Understanding the Risks Versus the Myths of Vaccines

The anti-vaccine movement that first took hold in the U.S. and spread globally has undermined advances against preventable infectious diseases such as measles and whooping cough. Now, so-called vaccine hesitancy is seen as a threat to the effective roll out of shots to prevent Covid-19, in the event they are developed. Certainly there are risks with new vaccines. But the belief among some people that well-established immunizations against childhood diseases are more dangerous than beneficial is based on a fraud.

1. What are the signs of Covid-19 vaccine hesitancy?

In a poll conducted for CNN in May, a third of people in the U.S. said they would not try to get a vaccine if one existed. One in six respondents in the U.K. said they definitely or probably would not get a Covid-19 vaccine in a YouGov survey in June.

2. What are the roots of vaccine hesitancy?

While opposition to immunizations has been around for as long as the shots, the most recent anti-vaccine movement took off after the medical journal The Lancet published what turned out to be a fraudulent study in 1998 linking the measles, mumps and rubella vaccine to autism, a developmental disorder associated with difficulties in speech or social interactions. The Lancet retracted the study in 2010 and the U.K.’s General Medical Council stripped its author, Andrew Wakefield, of his medical license for “dishonest” and “irresponsible” work. By then many parents had latched on to the idea that vaccines were to blame for a rise in autism diagnoses.

3. What does the evidence say?

Researchers have concluded that much if not all of the increase in autism prevalence is a result of greater awareness of the disorder and changes in how it’s diagnosed. While a true increase hasn’t been ruled out, repeated studies have debunked any connection to vaccines. The myth of a link expanded in 2005 with claims that the vaccine preservative thimerosal causes autism. Numerous studies have shown that vaccines containing thimerosal are safe.

4. What impact has the anti-vaccination movement had?

The number of children going unprotected from a variety of contagious illnesses has grown amid grassroots campaigns to convince parents incorrectly that immunizations often trigger side effects including autism. Fears that infants’ immune systems may be overwhelmed by multiple immunizations given at once has led some parents to space them out, though studies show they are safe when given simultaneously. The result is delayed protection and in some cases vulnerability when doses are missed entirely. Communities where anti-vaccine sentiment spreads can lose herd immunity, which occurs when so many people are protected a pathogen can’t take hold and dies out. That protection is essential for those who can’t get vaccinated, such as very young infants and people with certain medical conditions. Herd immunity can even benefit those who got vaccinated, since no immunization is perfectly effective.

5. What’s been the effect on public health?

Vaccine-preventable diseases are making a comeback in the U.S. and Europe, while efforts to slow them in poorer countries have stalled. Although vaccination eliminated measles from the U.S. in 2000, international travelers have brought the virus back each year since and sparked outbreaks among the unprotected. The situation is worse in Europe. Measles is on the rise throughout the world, with outbreaks reported in every region. The number of deaths rose to 140,000 globally in 2018, up from less than 90,000 in 2016. And it’s not just measles. Whooping cough, which can be lethal for babies, has remained at elevated levels since 2012, when it killed 20 people in the U.S. and 10 in the U.K.

6. What are the risks of new vaccines?

Before regulatory authorities license a new vaccine, it must be tested both for safety and efficacy in thousands of human volunteers. Still, there have been cases where safety issues have arisen after licensure. European regulators in 2011 recommended restricting the use of a new swine-flu vaccine from GlaxoSmithKline Plc after it was linked to rare cases of narcolepsy. A vaccine against Lyme disease developed by the same company, then called SmithKline Beecham, was pulled in 2002 amid concerns about links to arthritis. Some vaccines have been shown to do the opposite of what they’re designed to do by inducing unwanted immune responses. In the 1960s, an experimental vaccine for RSV, a common respiratory virus, not only failed to protect children, but made them more susceptible. Two toddlers died. In recent years, Sanofi’s dengue vaccine was found to exacerbate symptoms in some who received it.

7. How do authorities watch out for such cases?

Most advanced countries have established systems for reporting adverse side effect of vaccines. In the U.S., anyone can submit a report to the Vaccine Adverse Event Reporting System, which serves as an early warning system to identify side effects. The U.K. has a similar program, called the Yellow Card Scheme.

The Reference Shelf

  • A related QuickTake on the race to develop Covid-19 vaccines.
  • A U.S. Institute of Medicine report provides evidence for actual vaccine side effects.
  • This World Health Organization paper documents benefits of vaccination.

©2020 Bloomberg L.P.