Study registration: *
Publication Marti-nez Baz I, Euro surveillance, 2021
Dates: 2020-12-21 to 2021-09-13
Funding: Public/non profit (Horizon 2020 program of the European Commission; Carlos III Institute of Health / European Regional Development Fund )
Conflict of interest: no COI (None declared. )

Methods

Study design:Cohort
Description of participants: Close contacts of COVID-19 cases from 1 April to 31 August 2021 in Navarre, Spain.
Inclusion criteria:
  • Adults (≥ 18 years old)
  • close contact of a COVID-19 case (defined as any person who had had high-risk exposure to a confirmed COVID-19 case within a timeframe ranging from 2 days before the onset of symptoms in the case to 10 days after the onset of symptoms
  • or in the 2 days before the sample, which led to confirmation was taken, to 10 days after the sample was taken for asymptomatic cases) from 1 April to 31 August 2021.

Exclusion criteria:
  • Close contacts with a positive test for SARS-CoV-2 before January 2021, nursing home residents and those who did not complete the testing protocol
  • received the first dose <14 days before testing

Follow-up duration (months): 8.9
Vaccines:
  • 1 or 2 doses of ChAdOx1-S
  • 1 or 2 doses of mRNA-1273
  • 1 or 2 doses of BNT162b2
  • 1 dose of Ad26.COV2.S
Variant description :
Variant name: Delta
Evidence: Direct evidence (effectiveness determined by sequencing cases)
Documents
available

Protocol

NR

Statistical plan

No

Data-sharing stated: NR
Data accessibility: Correspondence: Jesús Castilla (jcastilc@navarra.es)

General comment Concerns over the lack of adjustment for important confounders, and no pre-defined statistical plan available.