Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 28, Number 1—January 2022
Research Letter

Cluster of SARS-CoV-2 Gamma Variant Infections, Parintins, Brazil, March 2021

Juliana F. da SilvaComments to Author , Roberto J. Esteves, Charlene Siza, Elaine P. Soares, Tatyana C. Ramos, Evelyn C. Campelo, Cristiano F. da Costa, Leila C. de Alencar, Rafaela P. Cavalcante, Clerton R. Florêncio, Tirza P. Mattos, Maria G. Bonecini-Almeida, Luciana Silva-Flannery, Barbara J. Marston, Juliette Morgan, Mateusz Plucinski, Felipe Naveca, and CDC Brazil Investigation Team1
Author affiliations: US Centers for Disease Control, Atlanta, Georgia, USA (J.F. da Silva, C. Siza, L. Silva-Flannery, B.J. Marston, M. Plucinski); US Centers for Disease Control and Prevention, Brasilia, Brazil (R.J. Esteves, J. Morgan); Secretaria Municipal de Saúde de Parintins, Parintins, Brazil (E.P. Soares, R.P. Cavalcante, C.R. Florêncio); Fundação de Vigilância em Saúde do Amazonas, Manaus, Brazil (T.C. Ramos, E.C. Campelo, C.F. da Costa, L.C. de Alencar); Laboratório Central de Saúde Pública do Amazonas, Manaus (T.P. Mattos); Fundação Oswaldo Cruz, Rio de Janeiro, Brazil (M.G. Bonecini-Almeida); Instituto Leônidas and Maria Deane, Manaus (F. Naveca); Team members are listed at the end of the article.1

Main Article


History of previous infection among 81 persons infected with SARS-CoV-2 Gamma variant, infected with SARS-CoV-2 non–Gamma variant, or not infected with SARS-CoV-2, Parintins, Brazil, March 2021*

Infection status No. (%)
p value (Gamma . negative)‡
Gamma variant, n = 31 Non–Gamma variant, n = 14 Negative, n = 36†
Previous infection according to clinical history
Yes 4 (13) 4 (29) 18 (50) 0.0016
27 (87)
10 (71)
18 (50)
IgG result at time of investigation
Positive 5 (16) 10 (71) 25 (69) <0.0001
26 (84)
4 (29)
11 (31)
Previous infection according to clinical history and positive IgG at time of investigation
Yes 0 3 (21) 16 (44) <0.0001
No 31 (100) 11 (79) 20 (56)

*9/90 patients refused nasopharyngeal swab sampling and were not included in the analysis. SARS-CoV-2, severe acute respiratory syndrome coronavirus 2. †By PCR. ‡By Fisher exact test.

Main Article

Page created: November 10, 2021
Page updated: December 20, 2021
Page reviewed: December 20, 2021
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.