key: cord-0939582-a6ftybkw
authors: Parker, Arifa; Dawood, Halima
title: SARS-CoV-2 transmission: time to rethink public health strategy
date: 2022-03-14
journal: Lancet Infect Dis
DOI: 10.1016/s1473-3099(22)00137-2
sha: c9b4e8945ff15e3c81048dd747399384bffc0667
doc_id: 939582
cord_uid: a6ftybkw

nan

As we enter the third year of the COVID-19 pandemic, many key questions about SARS-CoV-2 transmission dynamics remain unclear. 1, 2 In The Lancet Infectious Diseases, Cheryl Cohen and colleagues explore the nuances involved in SARS-CoV-2 household transmission. 3 Current evidence supports transmission between household contacts as a substantial driver of SARS-CoV-2 spread. 4, 5 Increased transmission in household settings is likely to be due to nonuse of personal protective equipment and close prolonged contact during daily activities within the household. 2 Although evidence shows that people with asymptomatic COVID-19 can transmit SARS-CoV-2, the exact extent of this transmission was not known. 1 The prospective household cohort study of SARS-CoV-2, influenza, and respiratory syncytial virus community burden, transmission dynamics, and viral interaction in South Africa (PHIRST-C) by Cohen and colleagues comprehensively investigated the incidence, reinfection, and transmission dynamics within urban and rural households in South Africa. 3 Novel study methodology included intensive symptom screening, midturbinate nasal swabs twice a week for testing of SARS-CoV-2 with real-time RT-PCR (RT-rtPCR; irrespective of symptoms), and anti-SARS-CoV-2 antibody testing every 2 months. The study period coincided with three COVID-19 waves in South Africa, which were driven by original wild-type variant in the first wave, the beta variant in the second wave, and the delta variant in the third wave.

The study reports that 749 (62·4%) of 1200 participants were infected with SARS-CoV-2, based on RT-rtPCR and serology combined, and 87 (11·6%) of 749 were reinfected. The prevalence of asymptomatic infection was high (565 [85·3%] of 662 RT-rtPCR-confirmed episodes with available data), even in older participants (≥19 years; 220 [76·1%] of 289), when compared with a previous systematic review of 79 studies (1287 [19·5%] of 6616). 6 In contrast to existing evidence, 5 7 Therefore, strengthening of antiretroviral treatment programmes is urgently needed, so that patients with advanced immunosuppression are prioritised for effective antiretroviral treatment and COVID-19 vaccination.

We think this study provides unique insights into the epidemiology of household transmission of SARS-CoV-2, in a largely unvaccinated population. The high prevalence of asymptomatic infection with similar transmission potential as symptomatic cases, and the need for frequent testing to detect transient infections, highlights the limitations and complexities of current screening and testing protocols. Symptom and temperature screening at entry points (eg, restaurants, schools, airports) might not have the public health infection containment benefit that was expected. Similarly, attempting to prevent nosocomial COVID-19 transmission by symptom and PCR screening on admission to hospital might miss transient infections if tests are not repeated regularly, given that patients with COVID-19 might not have symptoms, and transmission might have already occurred, despite a negative PCR test.

Current public health approaches encourage a combination of vaccination and non-pharmacological measures such as wearing a face mask, social distancing, hand sanitation, and ventilation strategies to prevent COVID-19 transmission. 1 

COVID-19): how is it transmitted?

Transmission of SARS-CoV-2: implications for infection prevention precautions

SARS-CoV-2 incidence, transmission, and reinfection in a rural and an urban setting: results of the PHIRST-C cohort study

Report of the WHO-China joint mission on coronavirus disease 2019 (COVID-19)

Factors associated with household transmission of SARS-CoV-2: an updated systematic review and meta-analysis

Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections: a living systematic review and meta-analysis

SARS-CoV-2 prolonged infection during advanced HIV disease evolves extensive immune escape