Models Show WNY Already Benefiting From Vaccinations

Distribution problems including weather delays have prevented as robust a rollout of the vaccinations as many would prefer, but even the current slow rate of vaccinations in Western New York is cause for cautious optimism, say the UB scientists.

“I was surprised that the vaccine effect shows up so quickly in our models,” says Peter Winkelstein, MD, executive director of UB’s Institute for Healthcare Informatics and clinical professor of pediatrics in the Jacobs School of Medicine and Biomedical Sciences.

He leads the UB team that has been modeling the spread of the SARS-CoV-2 virus since the start of the pandemic last March.

Like all models, the UB models rely on a number of assumptions, including that public health behaviors, such as masking, social distancing and hand hygiene, will continue at the same level, behaviors that Winkelstein says are “absolutely critical” to continuing to see these benefits.

There is reason for some optimism, he says, “so long as we don’t take our foot off the gas and we continue to engage in all the safety and public health measures.”

Epidemiological models of COVID-19 transmission developed by the UB data scientists have significantly expanded the parameters that such models typically reflect. The additional parameters range from behavioral factors to the level of vaccinations and potential scenarios that could result once new variants of the SARS-CoV-2 virus arrive.

While experts have warned that it could take longer than a year to vaccinate most people in Western New York, Winkelstein says there are factors to consider.

“Even though some estimates say it’ll take 15 months to vaccinate everybody, that’s not the critical number,” he says. “The question is, how many people need to be vaccinated in order to have an effect on spread in the community?”

And surprisingly, it’s already happening. While different endpoints can be used to demonstrate the effect of vaccinations, the UB models utilize the hospital census — the number of patients who are sick enough to be hospitalized with COVID-19 — as the key endpoint.

The UB models show that even 2,000 vaccinations a day, the level achieved in Western New York by mid-February, was sufficient to reduce hospitalizations.

“From the vaccine trial data, it looks like most of the vaccinations come close to 100 percent in preventing hospitalizations. We use 90 percent as the endpoint, meaning 90 percent of those who get vaccinated do not progress to significant illness,” Winkelstein says.

Another assumption that the models use is that the vaccines are 90 percent effective at preventing someone who’s been vaccinated from being contagious.

“The data are still preliminary on this, but there is good reason to believe that, too,” he says. “We think the vaccines are 90 percent effective in preventing disease and 90 percent effective in preventing transmission.”

“The vaccine effect seems to occur early,” he adds. “You don’t have to vaccinate everybody before you see a significant effect, even with the relatively slow rollout.”

He notes that the surges that began last fall and that caused cases locally and nationally to increase are now over and cases are on the decline. “That is really good news,” he says.

At the same time that the vaccinations are having an effect, Winkelstein concedes that the new variants, most prominently the B117 variant known as the UK variant, will begin to exert the opposite effect because of its increased transmissibility and the potential to cause more infections.

“The first sign that a variant is affecting a community,” Winkelstein says, “is when the positivity rate — the percentage of total COVID-19 tests that are positive — stops declining and starts going back up again.”

But the UB models also show a significant effect from vaccinations even once the variants arrive. To estimate that effect, the model assumed that the new variant will likely affect half of COVID-19 cases locally and will be 40 percent more transmissible than the original virus.

Even in that scenario, vaccines which are at least 50 percent effective against the variant — and the data suggest that they are likely more effective than that — will still reduce the impact on hospitalizations in Western New York.

The UB team has been doing presentations for the Erie County Department of Health on local transmission of the virus since last March. 

The team began with the classic Susceptible-Exposed-Infected-Recovered (SEIR) epidemiological models and has continually revised them based on changes in the rates of transmission and factors affecting transmission. Since last fall, the team made significant revisions to the models, dramatically expanding the parameters that the models reflect.

“We tuned the models for Western New York,” Winkelstein says. “We’ve taken the classic SEIR models and dramatically expanded them to deal with COVID-19 and our community, and added modeling of face mask use, social distancing, vaccine effects and variant effects. We think that’s unique.”

The addition of the effects of vaccines and the virus’ variants combine to make the UB models more sophisticated and significantly even more useful to the community.

In addition to Winkelstein, other members of the UB team include:

• Matthew R. Bonner, PhD, associate professor of epidemiology and environmental health in the UB School of Public Health and Health Professions
• Gabriel Anaya, MD, a trainee in the clinical informatics fellowship program, and Sarah G. Mullin, a student in the doctoral program in biomedical informatics, who both work under the supervision of Peter L. Elkin, MD, professor and chair of biomedical informatics