Halloween 2020 COVID Cases: How Will They Predict 2021?

Despite the availability of vaccines, Halloween may contribute to already-high COVID transmission rates

At the beginning of November 2020, the CDC reported, nationally, an 11.9 percent increase in COVID-19 cases between week 45 of the pandemic (ending Nov. 7) and week 46 (ending Nov. 14)—during the two weeks following Halloween.  Additionally, both hospitalizations and mortality surveillance remained above the epidemic threshold. Between week 45 and 46, numerous states reported several outbreaks due to Halloween gatherings.

This year, with vaccines now widely available, many are looking forward to in person Halloween gatherings. Studies find the mRNA COVID-19 vaccines (Pfizer and Moderna) reduce the risk of infection by 91 percent in those who are fully vaccinated. In regards to the Delta variant, the CDC states, “Fully vaccinated people with Delta variant breakthrough infections can spread the virus to others. However, vaccinated people appear to spread the virus for a shorter time.”

Due to the Delta variant, it is still recommended that everyone wear masks in public indoor spaces. However, unvaccinated people remain the greatest concern for both strains of the virus. Due to this, it is expected that that large, unmasked Halloween gatherings could lead to an increase in COVID cases among both the vaccinated and unvaccinated.

Last year, The Denver Channel reported on students at the University of Colorado Boulder “partying like it’s 2019.” Over the Halloween weekend, the Boulder Police Department issued at least 22 public health order violations, breaking up eight properties around University Hill.

The Denver Post then reported a surge in hospitalizations statewide, with around 13,799 infections reported during that following week. However, these numbers were not reported directly in relation to large Halloween gatherings.  

After seeing a mass spike in cases surrounding Halloween parties in Missouri, Kelley Vollmar, the health director for Jefferson County, Missouri, told ABC News, “Informal social gatherings, like Halloween parties, are ideal transmission sites for the virus because people let their guard down…They usually don’t social distance or wear a mask because they are with people they know and presume to be safe exposures.”

Each state released a set of guidelines in preparation for Halloween 2020. Colorado’s Department of Public Health and Environment originally released their guidelines early October 2020, but guidelines for this year’s holiday have since been updated. They encourage small indoor events, improving ventilation, organizing events outdoors if possible, and wearing proper facial coverings.

In June 2021, Colorado reported a “Third Wave of Covid.” This wave saw a mass spike in cases, hospitalizations, and death in the following weeks. Further, Colorado is ranked 7th worst in the increase in cases over the past two weeks as of Oct. 20 of this year as reported by Denver CBS4. They further reported that, according to a New York Times analysis, “Colorado stands out as one of only 10 states that saw infections increase during the past two weeks.” Considering the spike in cases seen following Halloween last year, conditions may worsen in the upcoming weeks. For more information go to Covid19.colorado.gov.