covid-19

Key Risk Factors for COVID May Have Changed in Massachusetts

Racial disparities in COVID incidence among Black communities in the Commonwealth may have decreased in the first eight months of the pandemic, but Latinx residents and essential workers remained at an elevated risk for exposure and infection.

Massachusetts was one of the hardest-hit states during the first wave of the pandemic in the US, and it soon became clear that COVID-19 exposure, cases, hospitalizations, and deaths disproportionately impacted certain populations, including Black and Latinx residents, low-income families, and essential workers. But few studies have explored whether and how case incidences among these groups have changed since the pandemic began.

Now, a new study by School of Public Health researchers has found that the magnitude of certain sociodemographic and economic risk factors among Massachusetts communities have changed since the outbreak first swept through the Commonwealth in March 2020.

Published in the journal BMC Infectious Diseases, the first-of-its-kind study found decreasing associations between town-level COVID-19 cases and the percentage of Black residents, as well as long-term care facility beds per capita, during the first several months of the pandemic. Conversely, the researchers found sustained elevated case incidence among towns with higher percentages of Latinx residents and essential workers.

“Throughout the pandemic, we’ve observed different patterns arising in case incidence, so we wanted to see if the communities with the most cases in the beginning of the pandemic still had higher numbers later in the year,” says Koen Tieskens, study lead author and a postdoctoral associate of environmental health.

The study findings indicate that early assumptions about COVID-19 vulnerability may not be accurate at all points of time, and that key predictors such as race, occupation, and housing density should be assessed regularly as human behavior, mitigation strategies, and policies continue to shift. The analysis also helped inform the Massachusetts Department of Public Health’s vaccination rollout, as the agency determined which populations should receive priority access to the vaccine given concerns about equity.

“Although we were unable to make statements of causality, collecting data at the community level provided a finer resolution at which we were able to observe notable and potentially actionable patterns of change in risk factors over distinct phases of the pandemic,” says Prasad Patil, co-author of the study and an assistant professor of biostatistics. “Our findings suggest that the relationship between individual exposure and factors that capture risk and vulnerability is variable and should be reevaluated regularly in the context of larger-scale shifts in overall case rates.”

For the study, the researchers analyzed publicly available COVID-19 case data for all 351 cities and towns in the Commonwealth from March 2020 to October 2020. They also reviewed sociodemographic, occupational, economic, and mobility datasets, and examined the data across five time periods, reflecting different waves of new cases during this time.

The data showed that before April 2020, towns with higher percentages of Black residents were associated with a 10 percent increase in COVID cases—but that association decreased over the next few months, and became null between September and October 2020. Similarly, the association between case incidence and proportion of town residents older than 80 years was stronger in spring 2020, and steadily decreased through the summer and early fall.

While the strength of the association between case rates and percentage Latinx residents fluctuated at times, it remained elevated throughout the study period. The researchers observed a significant positive association between COVID incidence and towns with more essential workers throughout all five periods.

Household transmission could potentially be a factor that is contributing to increased case levels among Latinx communities. The results showed that higher percentages of Latinx residents lived in towns with more occupants per household.

“Our key takeaway from this study is that social and demographic risk factors are modifiable in some circumstances, but there are some groups who remain at high risk,” says Jessica Leibler, corresponding author and assistant professor of environmental health.

“The decreasing association among towns with a greater number of Black residents may reflect the targeted outreach in Massachusetts within these communities,” Leibler says. “This could suggest that communication and collaboration at the community level are really powerful, but there are still groups who are at higher risk for exposure—and we might expect them to remain at higher risk to the current delta variant, especially in environments of uneven vaccination.”

The researchers say that this town-level data can help determine which community-level interventions are most effective, as well as inform future mitigation efforts, particularly for groups who are at elevated risk of exposure.

“As it relates to the risk of essential workers, our results give us reason to think that previous measures to protect them haven’t worked,” says Tieskens. “These people need to be at work, and it’s really important that policies address that. From a moral perspective, if we depend on people to do essential services, at least we can make sure that they’re the most protected.”

The study was co-authored by several faculty, students, and staff in the Department of Environmental Health at SPH, including chair and professor Jonathan Levy, doctoral students Paige Brochu and Beth Haley, assistant professor Kevin Lane, associate professor Patricia Fabian, and postdoctoral associate Keith Spangler.