Transmission from vaccinated individuals in a large SARS-CoV-2 Delta variant outbreak

Abstract

An outbreak of over one thousand COVID-19 cases in Provincetown, Massachusetts, in July 2021—the first large outbreak mostly in vaccinated individuals in the US—prompted a comprehensive public health response, motivating changes to national masking recommendations and raising questions about infection and transmission among vaccinated individuals. To address these questions, we combined genomic and epidemiological data from 467 individuals, including 40% of known outbreak-associated cases. The Delta variant accounted for 99% of outbreak-associated cases in this dataset; it was introduced from at least 40 sources, but 83% of cases derived from a single source, likely through transmission across multiple settings over a short time rather than a single event. Genomic and epidemiological data supported multiple transmissions of Delta from and between fully vaccinated individuals. However, despite its magnitude, the outbreak had limited onward impact in MA and the US, likely due to high vaccination rates and a robust public health response.

Omicron variant of SARS‐CoV‐2: Genomics, transmissibility, and responses to current COVID‐19 vaccines

“…41 Moreover, multiple Delta transmissions from and between completely vaccinated persons were confirmed using genomic and epidemiological data. 42 As vaccine-induced immunity is targeted through the spike proteins of the virus, heavily mutated Omicron variant spike protein is capable of reducing the neutralization activity of sera of vaccinated individuals that indicated less protection from Omicron variant. 26 Only 20% and 24% of BNT162b2 recipients had detectable neutralizing antibodies against the Omicron variants HKU691 and HKU344-R346K, respectively, but none of the Coronavac recipients did.…”

Vaccine Breakthrough Infection with the SARS-CoV-2 Delta or Omicron (BA.1) Variant Leads to Distinct Profiles of Neutralizing Antibody Responses

“…Breakthrough infection following SARS-CoV-2 vaccination has been observed since the rollout of vaccines 1,2 and has been associated with specific variants including Beta 3 , Delta 4 , and Omicron 5 . The predisposing factors to breakthrough infection and the consequences of breakthrough infection for SARS-CoV-2 immunity are poorly understood.…”

We Can Dance If We Want To (with Safety Measures)

“…For many who participate in social dance, it is a primary form of social interaction and exercise, so its absence has potential to impact both mental and physical health. The media have covered a number of social events that led to a high degree of SARS-CoV-2 transmission ( 5 , 6 ; and as reported by the Norwegian Institute of Public Health, https://www.fhi.no/en/news/2021/preliminary-findings-from-outbreak-investigation-after-christmas-party-in-o/ ). However, those cases did not require both vaccination and consistent mask wearing; thus, dancers did not have information available to weigh their risks.…”