Katherine E. Gallagher & Joyce Nyiro, Charles N. Agoti, Eric Maitha, James Nyagwange, Angela Karani, Christian Bottomley, Nickson Murunga, George Githinji, Martin Mutunga, Lynette Isabella Ochola-Oyier, Ivy Kombe, Amek Nyaguara, E. Wangeci Kagucia, George Warimwe, Ambrose Agweyu, Benjamin Tsofa, Philip Bejon, J. Anthony G. Scott, David James Nokes 

We estimated the secondary attack rate of SARS-CoV-2 among household contacts of PCR-confirmed cases of COVID-19 in rural Kenya and analysed risk factors for transmission. We enrolled incident PCR-confirmed cases and their household members. At baseline, a questionnaire, a blood sample, and naso-oropharyngeal swabs were collected. Household members were followed 4, 7, 10, 14, 21 and 28 days after the date of the first PCR-positive in the household; naso-oropharyngeal swabs were collected at each visit and used to define secondary cases. Blood samples were collected every 1–2 weeks. Symptoms were collected in a daily symptom diary. We used binomial regression to estimate secondary attack rates and survival analysis to analyse risk factors for transmission. Households in our setting experienced a lower 7-day attack rate than a recent meta-analysis indicated as the global average (23%–43% depending on variant), and infection is mostly asymptomatic in our setting.

Influenza & other Respiratory Diseases. September 2023