Recommended citation: Lopes H, Middleton J. ASPHER statement on the strategic use of masks. ASPHER (2020). DOI:10.13140/RG.2.2.25528.70403

The COVID-19 pandemic has raised debate on the use or non-use of masks by the general public in almost all European countries. Decision-making should be based on scientific knowledge, but where knowledge is incomplete as in the current pandemic, principles of precaution, and pragmatism, become increasingly important; political and professional judgements have played an increasing role.

ASPHER, follows the principle that decisions that affect the health of whole populations should be based on the best scientific evidence available. Our aim is to contribute a critical reading of the evidence so that decisions made by National or International Health Authorities may be more informed and effective with these contributions.

Public Health science is not exclusively a clinical or epidemiological enterprise. It involves also social, psychological and behavioural sciences in understanding individual and collective behaviours and beliefs. It recruits as well from ethics, economics and political science. In the context of mask use, we need to understand industrial processes, production, procurement and fairness in distribution. Public health insight and practice is central to an effective response to the threat posed by COVID-19 (SARS-COV-2 virus).

The ASPHER COVID-19 Task Force has concluded:

1. The use of masks is not a panacea to prevent viral transmission during an epidemic. It only makes sense as one element alongside other non-pharmaceutical measures (NPMs) (personal hygiene, physical distancing, and so on).

2. The need and function of masks differs at various phases of the epidemic. What is available from the evidence suggests that recommended mask use should change over the course of an epidemic:

• The widespread use of masks has not been verified prior to community transmission when it is still possible to identify the active transmission chains.
• Use of masks in the epidemic growth phase may mitigate viral transmission by asymptomatic patients and thus limit the epidemic’s growth rate. However, at this point in the outbreak, isolation and physical distancing are most important to control transmission; social mixing with masks should be discouraged.
• After the consolidated start of the decline in contagion processes and if economic activity is intended to re-start by the end of the confinement period, we do recommend use of masks. This is due to the intensification of the number of people in circulation and the return of citizens to living with older family members and populations at higher risk. At this stage, we recommend that, in addition to the portability of masks in public spaces, protective materials should be used when in contact with social groups vulnerable to COVID-19.
• No evidence was found for the widespread use of masks in the final phase of the epidemic.

3. ASPHER calls for the principle of a hierarchy of access to masks to be respected according to the degree of exposure risk. Namely by reserving FFP2 and FFP3 masks for health professionals caring for COVID-19 patients, other health professionals who may contact the virus and other workers playing critical roles to combat the epidemic

4. There is a worldwide shortage of professional masks. Non-medical grade “social” masks will have to be used,if the aim is to recommend or require mask use for the entire population. If not, there will be an aggravated shortage for health and other critical service workers and others at high risk, who need masks of adequate quality.

5. Imposing the use of masks has implications beyond viral transmission. Covering the face has sociological, personal image, religious and human rights implications. In taking a decision on mandatory or recommended use in public places, policymakers must evaluate freedoms and guarantees, aggravation of social inequalities and loss of normal human social interaction.

6. The use of masks does not prevent viral transmission by other means, namely through the hands when touching a contaminated mask. If widespread use of masks is implemented,this decision must be accompanied by a strong public training campaign by health authorities with quality assurance processes.

7. Only adequately produced masks can provide protections outweighing the risks of use. The option to use social masks requires immediate training for the public regarding which masks can present a barrier to viral transmission. Especially in homemade/DIY masks, clear instructions on the mask’s technical requirements must be made available and respected.

8. Non-clinical advantages can be invoked in favor of the use of social masks by the population, such as reduced demand for professional masks directed at health services; visual reinforcement of the need for physical distance; potential anticipation of economic activity. 

9. Personal Protective Equipment (PPE) has become an element of potential geopolitical interest and even national security. It is essential that lessons are learned and shared, and that countries and economical regions adequately strengthen manufacturing capacities, productive scalability, storage and distribution. In Europe, there is a risk for the pandemic to worsen if the few current PPE suppliers are unable or unwilling to continue supplying PPE. Masks are among the critical materials to safeguard.

10. States and Health Authorities must guarantee that legal and distribution control mechanisms are created to ensure the best and fairest possible use of the available masks at all times.

11. The public health community is heavily involved in seeking to address inequalities in health. The COVID-19 pandemic is widening inequalities and creating greater health problems for people in poorer social circumstances. The use of social masks may help to relieve situations of great poverty and social and mental distress.In countries without the capacity to have extended periods of confinement, the use of social masks can support, to some extent, a survival driven economic recovery by freeing up more activities.

12. There is a considerable absence of research and scientific knowledge on many analytical dimensions related to masks, including: 

1. Knowledge of the physical and mechanical properties of non-medical grade “social” masks.
2. Availability of new classes of masks produced using new materials or new technologies.
3. Psychological aspects related to the use of masks, including persuasion, impact, stigmatization, etc.
4. Clinical effectiveness and efficiency of the use of masks alone and in conjunction with other NPMs.
5. Specificities related to the use of masks in non-hospital practice/activities, with people with dementia or other psychological problems, and with young children.

ASPHER calls on the Faculties and Research Centers throughout Europe to contribute to fill the knowledge gaps that have been identified in almost every aspect relating to masks and their use.

ASPHER Statement on Masks in the press:

The Conversation: Distanciation sociale, masques, flot de données: les informations sont-elles pertinentes ? (In French)

Visão: Podemos lavar as máscaras sociais com o resto da roupa? Quantas vezes? E reutilizar as cirúrgicas? Guião para o uso correto das máscaras (In Portuguese) 

Bibliography of recent resources 
(Disclaimer: There is currently a great deal of work being undertaken to inform on various aspects of the COVID-19 epidemic. In an effort to keep up to date on the most recent developments, we will be listing recent publications that have became available since the publication of the ASPHER Mask Report. This is not an official endorsement of any one study or publication.) 

Advani S, Smith B, Lewis S, et al. Universal Masking in Hospitals in the COVID-19 era: Is it Time to consider Shielding? This is an Accepted Manuscript for Infection Control & Hospital Epidemiology as part of the Cambridge Coronavirus Collection. DOI: 10.1017/ice.2020.179 

Chu, Derek KChu, Derek K, et al. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. The Lancet. 2020. DOI:https://doi.org/10.1016/S0140-6736(20)31142-9