AsianScientist (May 29, 2020) – Wearing face masks, disinfection and social distancing in households might help limit the spread of COVID-19 infection among family members, suggests an observational study of 124 Chinese families published today in BMJ Global Health.
To date, the World Health Organization has not endorsed the wearing of face masks indoors or outdoors, on the grounds that there is little good quality evidence to warrant recommending this. In China, figures suggest that most of the person-to-person transmission of COVID-19 has occurred in families.
To explore if the wearing of face masks might help curb household transmission rates, a research team led by Zhang Ruiguang at the Union Hospital in Wuhan, China, questioned 460 people from 124 families in Beijing on their household hygiene and behaviors during the pandemic.
Each family had at least one laboratory confirmed case of COVID-19 infection between late February and late March 2020. The average family size was four, but ranged from two to nine, and usually comprised three generations. Family members were defined as those who had lived with the infected person for four days before and more than 24 hours after that person’s symptoms first appeared.
The researchers wanted to identify what factors might heighten or lessen the risk of subsequently catching the virus within the incubation period, defined as 14 days from the start of that person’s symptoms. During this time, secondary transmission—spread from the first infected person to other family members—occurred in 41 out of the 124 families. A total of 77 adults and children were infected in this way, giving an ‘attack rate’ of 23 percent, or around one in four.
Four behavioral and hygiene factors were significantly associated with secondary transmission of the virus. Diarrhea was associated with a quadrupling in risk; while close daily contact, such as eating meals round a table or watching TV together, was associated with an 18-fold increased risk.
Conversely, frequent use of bleach or disinfectants for household cleaning was 77 percent effective at stopping the virus from being passed on, and the wearing of a face mask at home before symptoms emerged, including by the first person to have them, were associated with a 79 percent reduction in transmission risk.
The authors acknowledge some key limitations with their study: telephone interviews are subject to recall and the strength of household disinfectants and bleach used was not recorded. Nevertheless, they suggest the findings back universal face mask use, not just in public spaces, and may be particularly relevant for families living with healthcare workers or quarantined family members.
“Household transmission is a major driver of epidemic growth,” the authors wrote, adding that their findings could be used to “inform precautionary guidelines for families to reduce intrafamilial transmission in areas where there is high community transmission or other risk factors for COVID-19.”
The article can be found at: Wang et al. (2020) Reduction of Secondary Transmission of SARS-CoV-2 in Households by Face Mask Use, Disinfection and Social Distancing: A Cohort Study in Beijing, China .
Source: British Medical Journal; Photo: Pexels.
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