Introduction

In the previous article, I discussed some aspects of pandemic containment and mitigation. This is the first article in a series that will discuss various non-pharmacological interventions for pandemic mitigation.

Non-pharmacological interventions (NPIs) include all measures or actions, other than the use of vaccines or medicines, that can be implemented to slow the spread of pandemic in a population.

In the early stage of viral epidemics and pandemics, NPIs are often the most accessible interventions, because of the time it takes to make specific vaccines available and because most locations do not have large stockpiles of antiviral drugs. Therefore, these mitigation measures will play a major role in reducing transmission in community settings. They are the only set of pandemic countermeasures that are readily available at all times and in all countries. The NPIs that will be discussed in this series include (not necessarily in this order):

1. Hand hygiene
2. Respiratory etiquette
3. Face masks for symptomatic persons
4. Isolation of sick individuals
5. Travel advice
6. Contact tracing
7. Quarantine of exposed individuals
8. Surface and object cleaning
9. School measures and closures
10. Face masks for public
11. Avoiding crowding
12. Internal travel restrictions
13. Border closure
14. Entry and exit screening
15. Workplace measures and closures
16. Lockdown  

Most of the strategies and interventions in use against COVID-19 were developed to deal with influenza epidemics and pandemics. In many respects, the current COVID-19 pandemic is similar to an influenza pandemic:

• It is caused by a new variant of an existing virus (similar to antigenic shift in influenza viruses).
• Disease transmission is mainly through contact (direct/ indirect), respiratory droplets/ droplet nuclei, with airborne (aerosol) transmission also suspected.
• There is no vaccine against the disease at present (similar to the initial months in an influenza pandemic).
• The population is susceptible to disease, and there is no innate immunity against the disease.

Despite the above, one cannot equate the COVID-19 pandemic with an influenza pandemic, as there are several differences between the two. Moreover, there are several gaps in our knowledge about COVID-19 and SARS-CoV-2 which preclude a comparison between the two viruses/diseases.

Nevertheless, we can examine the evidence for and against each NPI in the context of an influenza pandemic, and obtain a broad understanding of the possible usefulness of each NPI in COVID-19 pandemic mitigation.

It is important to note that even in the context of an influenza pandemic, the evidence base for NPIs is not very extensive or robust. Due to this one has to often make recommendations based on plausibility, reasoning and logic rather than scientific evidence.

The findings and recommendations presented in this article are mainly drawn from a 2019 World Health Organization publication: ‘Non-pharmaceutical public health measures for mitigating the risk and impact of epidemic and pandemic influenza’. The document was prepared by a Guideline Development Group that undertook systematic reviews to evaluate the evidence. The strength of recommendations were classified as:

• Recommended- the group is confident that the desirable effects outweigh the undesirable results
• Conditionally recommended- the group believes that the balance between benefits and harms is uncertain, and some conditions should apply when implementing the recommendation
• Not recommended- the group is confident that the disadvantages outweigh the advantages