Public Trust in Vaccine Information, Misrepresented Vaccine Studies, and HIV and PrEP Stigma

Flu Vaccine Study Misrepresented Online Amid Severe Season

Influenza deaths in the United States during the 2024-2025 flu season are higher than in previous years. Although the flu vaccine can prevent severe illness, hospitalization, and death, rates of vaccination have declined since 2020. The effectiveness of seasonal flu vaccines can vary year-to-year based on how similar the vaccine is to the circulating virus, but vaccines can offer protection against severe outcomes even when they are not well-matched to circulating strains. Data from the CDC supports the effectiveness of this season’s vaccine to protect against serious outcomes, and past data show that protecting against these outcomes is a primary benefit of the flu vaccine. As influenza deaths rise, the CDC continues to recommend that everyone 6 months of age and older receive a flu vaccine every season, with rare exceptions.

But some social media posts are sharing findings from a preprint study from researchers at the Cleveland Clinic to suggest that the flu vaccine is unsafe or ineffective without sharing context about the outcomes evaluated. The study, which has not yet been peer-reviewed, looked at more than 53,000 healthcare workers during the 2024-2025 flu season and found a higher rate of infection among those who were vaccinated. However, the authors explain that flu vaccine effectiveness depends on how closely the vaccine strains match the circulating virus in a given year. The study also did not evaluate the severity of illness, such as hospitalization or death, which are the primary outcomes vaccines are intended to prevent. Protection against infection with the flu can vary, but vaccines are consistently shown to reduce the risk of serious illness. After the study was posted online, a Cleveland Clinic spokesperson clarified to PolitiFact that the study did not represent the general public and does not suggest that flu vaccination increases the risk of flu.

After the study appeared on medRxiv, social media posts began circulating with misleading claims that the flu vaccine is ineffective or harmful. For example, one account that has previously shared false claims about vaccines online wrote, “Just like the COVID jabs and pretty much any other ‘vaccine’ it appears that the flu shot is an abject failure. In a preprint study from the Cleveland Clinic, employees that got the flu shot had a 27% HIGHER chance of contracting the flu.” Another post called for the removal of the flu vaccine from the market, “pending large prospective studies of their safety and effectiveness.” These posts do not acknowledge that the study did not evaluate severe outcomes. Their claims about the vaccine’s effectiveness, therefore, are misleading and unsupported by the study’s findings.

Despite these claims, most Americans remain confident in the flu vaccine’s safety. KFF’s latest April Tracking Poll on Health Information and Trust shows that most of the public (74%) is at least “somewhat confident” in the safety of the flu vaccines. While majorities across partisans express confidence in the safety of the flu vaccines, Democrats are more likely than Republicans to say they are “very” or “somewhat confident” vaccines for the flu are safe (88% v. 68%).

Misleading Claims About HIV and PrEP Resurface Amid Preventive Care Challenge

Stigmatizing claims about HIV and PrEP, a medication that can be taken to prevent HIV, continue to circulate online, reinforcing barriers to prevention. Such rhetoric has resurfaced in response to the Supreme Court case Kennedy v. Braidwood Management last month. The case challenges the Affordable Care Act’s preventive services mandate, which requires PrEP (as a highly rated preventive service) be covered without cost-sharing for most people with private insurance.

In their filings, the plaintiffs argue that requiring insurers to cover PrEP violates their religious beliefs “by making them complicit in facilitating homosexual behavior, drug use, and sexual activity outside of marriage between one man and one woman,” and that it promotes “homosexual behavior, prostitution, sexual promiscuity, and intravenous drug use.” A 2021 scoping review published in AIDS and Behavior found that PrEP-related stigma is common, often focusing on judgments about having sex without a condom or having multiple sex partners. Such beliefs may contribute to low uptake: in 2023, only 31.3% of people aged 16 and older with indications for PrEP were prescribed the drug.

However, the body of research around PrEP use and sexual risk behaviors is mixed as limitations make it difficult to draw generalizable conclusions. A 2018 systematic review found no conclusive evidence that PrEP use leads to increased sexual risk behaviors. On the contrary, the review found that offering PrEP services provides an opportunity for at-risk populations to access sexual health care, testing, treatment, and counseling that they would not otherwise receive. Multiple studies have shown that when taken as prescribed, PrEP reduces the risk of acquiring HIV through sex by about 99% and through injecting drug use by at least 74%. 

Fast Track Designation for Bird Flu Vaccine Contributes to Claims that Threat of Bird Flu is Manufactured

Online conversations about bird flu spiked on April 10 after a vaccine manufacturer announced that the FDA had granted Fast Track designation to its mRNA vaccine candidate. The designation is meant to speed up the development and review process for promising vaccines targeting major public health threats. In this case, it will help accelerate clinical trials for the vaccine, which began Phase 1 in November 2024 with federal funding.

The day before the announcement, a self-described news account with over 369,000 followers on X posted that Pfizer and Moderna were in talks with the government to develop bird flu vaccines. Although HHS had previously awarded $590 million to Moderna to support development, Pfizer has not received the same designation or funding. Still, among the more than 10,000 comments on the post, many of the most-engaged-with responses amplified the idea that preparing for a potential outbreak suggests the threat is exaggerated or manufactured. Others have misrepresented the meaning of “fast track,” falsely suggesting that the vaccine is being rushed without proper safety testing, when, in reality, the designation allows for more frequent communication with the FDA and eligibility for priority and rolling review—it does not mean safety protocols are bypassed.

AI-Generated Messages Show Mixed Results in Correcting Vaccine Misinformation

A study from a researcher at the University of Michigan explored how generative AI can help public health communicators craft messages tailored to specific audiences. The experiment tested AI-generated corrections for vaccine misinformation, customized to match personality traits like extraversion or beliefs in pseudoscience. Participants rated their agreement with vaccine misbeliefs before and after receiving a correction, which was either AI-generated or drawn from real-world examples.

Messages tailored to extraversion performed as well as high-quality generic messages, especially among those who scored high in extraversion. But, messages aimed at people with strong pseudoscientific beliefs were ineffective and, in some cases, backfired, reinforcing skepticism. The study’s author concluded that while well-targeted AI-generated messages show promise, some messages may be counterproductive, underscoring the need for human oversight. The study adds to research examining the use of AI in public health communication. A 2023 systematic review in Journal of Medical Internet Research found that conversational AI tools can be effective in vaccine communication, especially when messages are personalized.

The findings highlight both the potential and limitations of using AI in public health messaging. KFF polling has shown that trust in AI-generated content remains low: most of the public (56%) – including half of adults who use AI — are not confident that they can tell the difference between what is true and false when it comes to information from AI chatbots.