Boosting vaccination uptake using wastewater surveillance: a county-randomized controlled trial

Vaccines are one of the most powerful tools humanity has developed to stop disease, yet their success depends entirely on people choosing to get them. When large numbers of people hesitate to vaccinate, communities become vulnerable to outbreaks of illnesses that could otherwise be prevented. This hesitation often stems from a lack of trust, a feeling that the disease is not a real threat, or simply the difficulty of finding a convenient place to get a shot. Public health officials have long tried to overcome these barriers by telling people why vaccines are safe and effective, but finding the right moment to deliver that message has always been a challenge. The core idea behind this new research is that people are more likely to act when they feel a risk is immediate and personal. If a community could see clear, local evidence that a virus is spreading right now, perhaps that sense of urgency would be enough to tip the scales toward vaccination.

To test this idea, a team of researchers in New York State launched a large experiment involving forty counties across the state. They wanted to see if a social media campaign, driven by real-time data from local wastewater, could encourage more people to get their seasonal COVID-19 and flu shots. The logic was straightforward: wastewater surveillance acts as an early warning system. By testing the sewage in a community, scientists can detect rising levels of viruses like SARS-CoV-2 and influenza before hospitals even see a spike in patients. The researchers hypothesized that if they took this local data and turned it into a simple, direct message on social media—telling residents, "The virus is rising in your town right now, and here is how you can protect yourself"—it would make the threat feel more real and the solution more accessible. They set up a randomized trial where twenty counties received these targeted ads, while the other twenty counties did not, allowing for a direct comparison of what happened in each group.

The campaign ran for eleven weeks during the fall of 2024, a critical time when respiratory viruses typically begin to circulate. In the counties that received the ads, the messages appeared on Facebook, Instagram, and NextDoor, platforms where many adults spend their time. The ads featured videos and images with a clear headline: "Trust your gut, trust your data." They explained that wastewater testing showed the virus was increasing in the local community and urged residents to get up to date on their vaccines. Each advertisement included a link that took people directly to a website where they could see the specific data for their area and find locations to get vaccinated. The campaign was extensive, reaching more than 16.6 million views and generating over 77,000 clicks on the link to get more information, showing that the public was indeed paying attention to the message.

When the researchers looked at the results, the picture was mixed. During the weeks the campaign was running, the counties that saw the ads did administer significantly more doses of the COVID-19 vaccine compared to the counties that did not see the ads. Specifically, there were about 77 additional doses given per 100,000 residents each week in the intervention group. However, the story was different for the flu vaccine. During the same period, the counties with the ads actually saw a smaller increase in flu shots compared to the counties without the ads. When the researchers stepped back to look at the entire season rather than just the weeks of the campaign, the differences disappeared entirely. By the end of the season, the total number of people who got vaccinated in the counties with the ads was not statistically different from the total in the counties without them, for either the COVID-19 or the flu vaccine.

This outcome suggests that while the wastewater-based messaging was successful at creating a short-term spike in activity for one type of vaccine, it did not fundamentally change the overall behavior of the community over the long term. The campaign proved that people would engage with the message and click the links, but that engagement did not translate into a lasting shift in vaccination rates for the whole season. The researchers noted that changing how people make health decisions is incredibly difficult, and simply knowing that a virus is present in the local sewage might not be enough to overcome other barriers, such as fear of side effects, lack of time, or confusion about which vaccine is needed. The study did not find evidence that this specific approach could solve the broader problem of vaccine hesitancy, but it did demonstrate that wastewater data can be used to create timely, local public health messages that capture the public's attention. The findings suggest that while this tool is promising for generating immediate interest, it may need to be part of a larger, more comprehensive strategy to truly boost vaccination rates across a community.