Dr. Jillian Irwin, medical director and deputy director for clinical services at the Allegheny County Health Department. (Courtesy of the Allegheny County Health Department)
Vaccines remain one of the most effective tools for preventing the spread of infectious diseases. But in recent years, social media misinformation and flawed science have fueled skepticism, contributing to declining vaccination rates
According to the CDC, vaccination coverage among 2-year-olds born in 2020-21 declined 1 to 2 percentage points for several routine childhood vaccines compared with children born in 2019-20. Flu shots dropped 7.4 percentage points. The measles, mumps and rubella vaccine coverage rate among that same population sat at 90.8%, which falls below the 95% threshold needed for community immunity
Dr. JillianIrwin, medical director and deputy director for clinical services at the Allegheny County Health Department, explained why we’re seeing some of these trends and why it’s important to reverse them
Q: Why is it important to get vaccines widely recommended by the medical community?
A: When physicians and public health experts recommend a vaccine, that recommendation reflects years — sometimes decades — of scientific research. Vaccines undergo laboratory testing, multiple phases of clinical trials involving thousands of participants and continued safety monitoring after they become available to the public. Recommendations are not static; they are continually reassessed as new evidence emerges
The central question is always the same: Does the benefit of vaccination outweigh the risk for the population being vaccinated? For vaccines that are routinely recommended, the answer is overwhelmingly yes
Many infectious diseases spread from person to person. When enough people are immune, transmission slows, helping protect those who are most vulnerable, including infants, older adults, people undergoing chemotherapy, transplant recipients and others whose immune systems may not respond well to vaccines
One of the challenges we face today is that vaccines have been so successful that many people have never seen the diseases they prevent. Most younger physicians have never cared for a patient with polio. Many parents have never seen a baby hospitalized with whooping cough or a child develop brain inflammation from measles. As these diseases become less visible, it’s understandable that the benefits of preventing them become less tangible
Q: What do vaccines do for the body?
A: Rather than waiting until someone is infected, a vaccine safely introduces the immune system to part of a virus or bacterium, or, in the case of newer technologies like mRNA vaccines, the instructions to temporarily make a harmless piece of it. This allows the immune system to develop antibodies and immune memory without experiencing the disease itself
If you’re exposed later, your immune system recognizes the threat much more quickly and can respond before the infection becomes severe. Depending on the disease and the vaccine, that may prevent infection entirely or significantly reduce the risk of hospitalization, serious complications or death
Q: What happens if people don’t get a tested and approved vaccine?
A: The answer depends on the disease, but in general when vaccination rates decline, infectious diseases have more opportunities to spread
We’ve seen this happen repeatedly throughout history. Measles is one of the clearest modern examples. Although it was declared eliminated from the United States in 2000, we’ve seen outbreaks return in communities where vaccination rates have fallen. Similar trends have occurred with pertussis, or whooping cough
Public health isn’t about eliminating every risk — that isn’t possible. It’s about reducing preventable illness while respecting people’s ability to make informed decisions
Q: When is skepticism of a given vaccine warranted?
A: Patients should ask questions about any medical intervention, including vaccines. It’s appropriate to ask how well a vaccine works, what side effects have been observed, whether there are alternatives and whether a recommendation applies to their specific health situation
Science doesn’t aim to create permanent recommendations. Good science is inherently flexible: It involves adjusting recommendations, if appropriate, as additional, high-quality evidence becomes available. We’ve seen examples where vaccine recommendations have changed because new safety data emerged or because the disease itself became less common. That’s evidence that the system is working, not that it failed
Q: Why do some believe some approved, tested and widelyused vaccines are unsafe?
A: Different people arrive at vaccine concerns for many different reasons. Some have had difficult experiences with the healthcare system. Others have concerns about pharmaceutical companies or government institutions. Social media has also made it much easier for inaccurate information to spread quickly, especially when it’s tied to emotionally powerful personal stories
We do not aim to be dismissive of those concerns or even assume people are acting in bad faith. Asking questions about medical care is completely reasonable. At the same time, it’s important to distinguish between personal experience and rigorous scientific evidence. Public health recommendations are not based on one story or one study. They are based on the totality of evidence collected from millions (and in some cases, billions) of people over time
Q: Have any vaccines been linked to autism by legitimate studies?
A: No. This particular question has been studied extensively for more than two decades. Large studies involving hundreds of thousands of children in multiple countries have consistently found no evidence that vaccines cause autism. Much of the concern originated from a small study published in 1998 by Andrew Wakefield that was later found to contain serious scientific and ethical problems. The paper was ultimately retracted, and its conclusions have not been supported by subsequent research
Q: What are the currently recommended vaccines for kids? Adults?For thosetraveling?
A: The answer depends on a person’s age, medical history, occupation and travel plans
Children routinely receive vaccines that protect against measles, mumps, rubella, polio, whooping cough, meningitis, hepatitis, HPV, influenza, covid and others according to the CDC immunization schedule
For adults, recommendations include annual influenza vaccination, tetanus boosters every 10 years, shingles vaccination beginning at age 50, pneumococcal vaccination for older adults and certain medical conditions, RSV vaccination for eligible older adults, hepatitis B vaccination for many adults, and covid-19 vaccination for those who choose it after discussing current recommendations with their healthcare provider
Travel medicine is highly individualized. Depending on where someone is traveling, additional vaccines — such as yellow fever, typhoid, Japanese encephalitis or rabies — may be recommended or even required. That’s why we encourage international travelers to meet with a travel medicine provider at least four to six weeks before departure
Q: What side effects might I commonly experience after receiving a vaccine?
A: Most vaccine side effects are mild and short-lived. The most common are soreness at the site where the shot was given, fatigue, headache, muscle aches or a low-grade fever for a day or two. Those symptoms are actually signs that the immune system is responding appropriately to the vaccine. Serious side effects are uncommon, and severe allergic reactions are very rare
Q: What are some new and exciting developments in vaccines?
A: We are entering an exciting period in vaccine science. The success of mRNA technology has accelerated research into vaccines that may be developed more quickly and updated more efficiently as viruses change
Researchers are also working on next-generation flu vaccines that could provide more agile, longer-lasting protection, as well as vaccines for diseases like HIV, Lyme disease and certain cancers
One of the most exciting developments is the possibility of personalized cancer vaccines, which use a patient’s own tumor to train the immune system to recognize and attack cancer cells. While this work is still evolving, early studies have been very encouraging
About the Writer
Josh Ewers is a TribLive staff writer
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