Individual measures to limit transmission
In this article, Emilio Hornsey gives an overview of methods to reduce individual risk of infection.
Infection prevention advice to individuals has the potential to reduce transmission of SARS-CoV-2 causing COVID-19, and if the advice is timely, clear and easy to understand it may also improve confidence in the response and give individuals a sense of control. It is important therefore that any advice to individuals is considered, evidence based, rational and coherent1.
Here follows some of the individual measures to protect against infection with SARS-CoV-2, that have been consistently recommended by WHO2 and others. In practice, most of these interventions are bundled together, so it is hard to know which are most effective.
Cough hygiene: A cough should be caught in a single use tissue, or the crook of the elbow. The tissue should be immediately disposed of and hand hygiene performed. Coughing into bare hands means they can become heavily contaminated; unless immediate and thorough hand hygiene is performed, they can become a vehicle for transmission. Cough hygiene can reduce, but not totally eliminate, droplets being released by a cough or sneeze3, 4.
Avoiding face touching: Avoiding face touching is a self-protective measure. The risk is that contaminated hands can contact mucosal surfaces and cause an infection. The extent of its role in transmission of infection has not been thoroughly investigated. People have been observed to touch their face 23 times per hour5 and more in times of stress and in some social groups6.
Social distancing: Social distancing is a series of measures which include minimising social contact of large groups of people in crowded spaces. It may also involve minimising physical contact through actions like hand shaking and kissing as a greeting, depending on social norms, which are culturally specific. Social distancing can protect both the individual and others around them. While the principle behind the intervention(s) is sound, it is difficult to calculate the impact of each element7.
Self-isolation: Self isolation is a more extreme form of social distancing, it has been recommended for high-risk contacts and for those with mild symptoms who do not require medical care. The isolation of asymptomatic high-risk contacts is rational if there is strong evidence of pre or asymptomatic infection8. However mass isolation may have major social and economic effects9 so the risks and benefits should be balanced, and may be tailored according to risk, or consequences of, infection.
Hand hygiene: Frequent hand hygiene with either soap and water, or alcohol-based hand rub. Key moments are after using the toilet, coughing or sneezing, before preparing food or eating, after touching communal surfaces such as door handles and before touching your face. Hand hygiene should be thorough, to decontaminate all areas of the hands10.
Face masks: The value of wearing these outside health care settings is controversial11 but it is one of the most visible features of the response in many areas. The evidence for the protective effect of asymptomatic individuals wearing masks is weak12 and facemasks may change face touching behaviour if they become uncomfortable and need adjusting13. There is evidence that wearing a mask reduces the droplet spray if individuals cough or sneeze1. Social distancing and cough hygiene are other measures that can be instituted to control the effect of droplet spread.
Other advice (less consistently seen) includes:
Avoiding wet/live meat markets: This is only relevant in areas where these exist. Many early cases were associated with the Huanan seafood market for this outbreak14 but it is not clear that this is where zoonotic transmission (spread from animals to humans) occurred. Without evidence of multiple events where zoonotic transmission of SARS-CoV-2 has occurred in wet/live meat markets, this measure won’t affect the course of this outbreak, but it could reduce the risk of a similar future emergence.
Active monitoring of health after travel to areas with transmission:15 As areas of ongoing transmission shift this advice will need regular updating.
Avoiding close contact with anyone who is sick:16 This is the other side of self-isolation but will be harder to adhere to for people with caring responsibilities.
Not spreading rumours:17 This advice acknowledges the risks associated with misinformation, as described in the article on risk communication and community engagement in Week 1.
Regular household surface disinfection:18
Avoiding spitting in public:19 In some cultures public spitting is much less socially acceptable in general so a specific injunction isn’t required.
The same interventions may be presented in different ways20, 21. For example, in more individualised cultures the explanation may be more rooted in self-protection, whereas in collectivist cultures the justification may be rooted in protection of others.
© London School of Hygiene & Tropical Medicine 2020